diclo invitro

COMPARISON OF IN-VITRO RELEASE PROFILE OF DICLOFENAC FROM

VARIOUS FORMULATIONS

By

Ms. Patel Ruchita Girishchandra, B.Pharm

Reg. No-04PU754

A dissertation submitted to the RAJIV GANDHI UNIVERSITY OF HEALTH SCIENCES,

KARNATAKA, BANGALORE.

In partial fulfillment of the requirements for the degree of

Master of Pharmacy In

PHARMACEUTICS

Under the Guidance of

Mr. Sreedharan, M.Pharm

Department of Pharmaceutics Nitte Gulabi Shetty Memorial Institute of Pharmaceutical Sciences

Mangalore – 575 005

December 2005

NITTE GULABI SHETTY MEMORIAL INSTITUTE OF

PHARMACEUTICAL SCIENCES MANGALORE – 575 005

Certificate

This is to certify that the dissertation entitled “COMPARISON OF

IN-VITRO RELEASE PROFILE OF DICLOFENAC FROM VARIOUS

FORMULATIONS” is a bonafide research work done by Ms. Patel

Ruchita Girishchandra submitted in partial fulfillment for the award of

the degree of “Master of Pharmacy” in Pharmaceutics of the “Rajiv

Gandhi University of Health Sciences”, Karnataka. This work was carried

out by her in the library and laboratories of NGSM Institute of

pharmaceutical sciences, Mangalore, under my guidance and direct

supervision.

Date : Mr. SREEDHARAN., M. Pharm., Place : Mangalore Assistant Professor, Dept. of Pharmaceutics

NGSM Institute of Pharmaceutical Sciences Mangalore - 575 005

NITTE GULABI SHETTY MEMORIAL INSTITUTE OF

PHARMACEUTICAL SCIENCES MANGALORE – 575 005

Endorsement


IN-VITRO RELEASE PROFILE OF DICLOFENAC FROM VARIOUS

FORMULATIONS” is a bonafide research work done by Ms. Patel

Ruchita Girishchandra under the direct supervision and guidance of

Mr. Sreedharan, M. Pharm, Assistant Professor, Department of

Pharmaceutics, NGSM Institute of Pharmaceutical Sciences, Mangalore.

Date : Prof. Dr.D. Satyanarayana , Place : Mangalore M. Pharm, Ph.D., FIC.

Director (PG and Research studies) NGSM Institute of Pharmaceutical Sciences

Mangalore - 575 005

NITTE GULABI SHETTY MEMORIAL INSTITUTE OF PHARMACEUTICAL SCIENCES

MANGALORE – 575 005


IN-VITRO RELEASE PROFILE OF DICLOFENAC FROM

VARIOUS FORMULATIONS” is a bonafide research work done by

Ms. Patel Ruchita Girishchandra under the direct supervision and

guidance of Mr. Sreedharan, M.Pharm, Assistant Professor, Department

of Pharmaceutics, NGSM Institute of Pharmaceutical Sciences,

Mangalore.

Prof. M. V. Ramana, M. Pharm. Head, Department of Pharmaceutics NGSM Institute of Pharmaceutical Sciences, Mangalore - 575 005.

Prof. Dr. E.V.S.Subrahmanyam, M.Pharm, Ph.D., Principal NGSM Institute of Pharmaceutical

Sciences, Mangalore - 575 005.

Date :

Place : Mangalore

Date :

Place : Mangalore

Endorsement

ACKNOWLEDGEMENT

“Gratitude makes sense of our past, brings peace for today and creates a

vision for tomorrow”.

I humbly owe the completion of this dissertation work to the almighty for

his everlasting love and blessings on me.

It is a delightful moment for me, to put into words all my gratitude to my

esteemed guide Mr. Sreedharan, Assistant Professor, Dept. of pharmaceutics,

NGSMIPS, Mangalore, for his unstinted guidance.

At first, I consider it as a great privilege to express my heartfelt gratitude

and sincere thanks to Mr. Prabhakara Prabhu, Assistant Professor Dept. of

Pharmaceutics, NGSMIPS, Mangalore, for his valuable suggestions, constant

encouragement, optimism towards problems, till the moment I finished my work,

are highly admirable.

I am deeply indebted to Prof. Dr. D. Satyanaryana, Director (PG Studies

and Research), for his constant encouragement and ever willingness to provide

the necessary facilities during the entire course of study.

I specially convey my gratitude and warm thanks to Prof. Dr. E. V.S.

Subrahmanyam, Principal, for his support, valuable and generous help and

constant encouragement.

My deepest appreciation and heartfelt thanks to Prof. M. V. Ramana,

Head of the Department of Pharmaceutics for his valuable suggestions and help

in making my study a success. I cherish his co-operation throughout my life.

I specially thanks to Prof. Dr. R. Narayana Charyulu, M. Pharm, Ph D,

Departmaent of Pharmaceutics, Prof. C.G.Geetha Rao, Department of

Pharmaceutics, Mrs. Marina Koland, M. Pharm, Department of Pharmaceutics,

Mr. Ramkrishna Shabaraya, M. Pharm, Department of Pharmaceutics, for their

constructive suggestions.

My genuine thanks to Dr. Ishwar Bhat, Dr. Himja Ramana, Mrs. Jennifer

fernandes, Mr. Ronald fernandes, Mr. Revanasidappa, Mrs. Jane Jocob

Department of Pharmaceutical Chemistry, Dr. Arun B. Joshi,

Mr. Chandrashekar Department of Pharmacognosy and Phytochemistry.

Dr. Prashanth Shetty, Mr. Vijayanaryana, Mr. Yogendra Nayak and

Mr. Prasanna, Department of Pharmacology for their constant support and

encouragement.

Thanks to Mr. Rajaram Shetty, Mr. Pradeep Hegade, Mr. Shashidhar

rai, Mr. Ravindranth Poonja, Mr.Balakrishna, Mr. Gururaj Mrs. Vidyavathi

Mrs. Jyothi Shetty, Mrs. Usha Kumari and Mr.Jagannath for their kind co-

operation and constant help.

Words cannot express my heartfelt appreciation to my ever loving,

affectionate, Beloved Daddy, Mummy, Nilafoi, brother Niketan, sister Vidita and

all other family members for their life time support, everlasting love,

encouragement and prayers without which I would not have achieved my goal

I would like to convey my special thanks and deep sense of gratitude to my

beloved “Daddy” because of whom, I stand where I am today.

Words cannot express my heartfelt gratitude and special thanks to my

Beloved husband Kinjal, Father-in-law, Mother-in-law and all other family

members for their everlasting love prayers and encouragement in carrying out my

work.

I specially convey my gratitude to all my friends Raghav, Brijesh, Vipin,

Gunjan, Kantharaj, Srikanth, Jignesh, Santosh, Vimal, Venkatesh, Ashish,

Paro, Nirmala, Abinash, Amit, Nimesh and all my senior friends. I would like to

appreciate their moral support and concern shown to me.

I specially convey my thanks to Uncle, Aunty, Saloni, Nikita, Pratiksha

and Urvashi for their constant encouragement and love.

I would like to convey my special thanks to the staff of Saraswati

Graphics for their fast and efficient work.

Finally, I take the privilege to express my sincere thanks to one and all for

their affection and best wishes for the successful completion of this work.

Date:

Place: Mangalore Patel Ruchita Girishchandra

COPYRIGHT

I hereby declare that the Rajiv Gandhi University of Health Sciences,

Karnataka shall have the rights to preserve, use and disseminate this

dissertation/ thesis in print or electronic format for academic/ research

purpose.

Date : Place : Mangalore Ms. Patel Ruchita Girishchandra © Rajiv Gandhi University of Health Sciences, Karnataka

Rajiv Gandhi University of Health Sciences, Karnataka

Declaration

I hereby declare that the matter embodied in the dissertation entitled “COMPARISON

OF IN-VITRO RELEASE PROFILE OF DICLOFENAC FROM VARIOUS

FORMULATIONS” is a bonafide and genuine research work carried out by me

under the guidance of Mr. Sreedharan., M. Pharm, Assistant Professor, Department

of Pharmaceutics, NGSM Institute of Pharmaceutical Sciences, Mangalore.

Date :

Place : Mangalore

Patel Ruchita Girishchandra

Table of Contents

Topic name P a g e N o .

Abstract i - i i

List of tables iii

List of figures iv

List of abbreviations v

Chapter - 1

Introduction 1-6

Chapter - 2

Objective 7-8

Chapter - 3

Review of Literature 9-21

Chapter - 4

Methodology 22-31

Chapter - 5

Results and Discussion 32-64

Chapter - 6

Summary

65-66

Chapter -7

Conclusion 67-68

Chapter - 8

Bibliography 69-73

Abstract

Department of Pharmaceutics, N.G.S.M.I.P.S, Mangalore. i

ABSTRACT

The objective of this study is to prepare calcium salts of diclofenac, and

evaluating its release property from conventional and matrix tablets and compare it

with the release property of diclofenac sodium from conventional and matrix tablets

in order to produce sustained effect of diclofenac. Calcium salt of diclofenac was

prepared by precipitating from the solution of diclofenac sodium by adding of calcium

chloride solution. Alginate matrix of diclofenac was prepared using ionic gelation

method (using 2%CaCl2 solution), then matrix was dried and evaluated for its

entrapment efficiency and compressed into tablets by direct compression method. The

tablets were subjected to thickness, weight variation, drug content, hardness,

friability, and in-vitro release studies. All the tablet formulations showed acceptable

pharmacotechnical properties. The USP paddle method was selected to perform the

dissolution, in 900ml of pH7.2 phosphate buffer. Diclofenac calcium from

conventional tablets showed slow release up to 6 hours compared to diclofenac

sodium, released in 1 hour. This may be due to the better solubility of sodium salt

compared to the calcium salt and was found to be suitable for sustained release

formulation. Diclofenac sodium matrix tablets of ratio 1:2 (drug: alginate) exhibited

slow release (98% of the drug release in 8 hours) and was found to be suitable for

sustained release formulation, which was not possible with the matrix tablets of

diclofenac calcium, since it released the drug at much faster rate in 3 hours. IR spectra

revealed that there is a mixture of diclofenac sodium and diclofenac calcium in

alginate matrix. Though on the basis of solubility profile, the release of diclofenac

sodium was expected to be faster compared to calcium salt, released at much slower

rate from matrix tablet. Since calcium is a divalent ion there may be a complex

formation between alginate, diclofenac calcium and believed to be responsible for the

Abstract

Department of Pharmaceutics, N.G.S.M.I.P.S, Mangalore. ii

slow release of drug. The drug content in all the formulations remained within the

limits when stored at different temperatures. The best-fit release kinetics was achieved

with zero-order plot followed by Higuchi equation. It was concluded from the study

that, diclofenac calcium might be used as sustained release salt. Compared to

conventional tablets of diclofenac sodium, release of diclofenac calcium from

conventional tablets and diclofenac sodium from matrix tablets was prolonged.

Keywords: Sustained release, Diclofenac sodium, Sodium alginate, Calcium chloride,

and Matrix tablet.

iii

List of Tables

Sl. No Tables Page No.

Table 1: List of retardant material used in the matrix. 3

Table 2: Composition of conventional tablet. 25

Table 3: Quantity of drug and polymer used in the preparation of matrix. 26

Table 4: Composition of matrix tablet. 27

Table 5: Standard calibration data of diclofenac sodium in phosphate buffer pH 7.2.

32

Table 6: Solubility of diclofenac sodium and diclofenac calcium in distilled water.

34

Table 7: Percentage yield of diclofenac in matrix of sodium alginate. 34

Table 8: Drug content in matrix. 35

Table 9: Physical properties of tablets. 38

Table 10: Drug content of tablets. 38

Table 11: Dissolution data of F1 (Conventional tablets of diclofenac sodium).

39

Table 12: Dissolution data of F2 (Conventional tablets of diclofenac calcium).

39

Table 13: Dissolution data of F3 (Diclofenac sodium matrix tablets 1:1). 41

Table 14: Dissolution data of F4 (Diclofenac sodium matrix tablets 1:2). 42

Table 15: Dissolution data of F5 (Diclofenac calcium matrix tablets 1:1). 43

Table 16: Dissolution data of F6 (Diclofenac calcium matrix tablets 1:2). 44

Table 17: Dissolution data of Voveran – 50 (Conventional tablet). 49

Table 18: Dissolution data of Nac – 50 (Conventional tablet). 49

Table 19: Dissolution data of Voveran SR – 100 (Sustained release tablet). 50

Table 20: Dissolution data of Divon SR – 100 (Sustained release tablet). 51

Table 21: Comparison of regression co-efficient values for different formulations.

60

Table 22: Regression co-efficient values of different formulation for higuchi plot.

60

Table 23: Percentage drug content of formulations F3 and F4 under different temperature conditions.

63

Table 24: Percentage drug content of formulations F5 and F6 under different temperature conditions.

64

iv

List of Figures

Sl. No Figures Page No.

Fig 1 Release of drug from matrix diffusion controlled drug delivery system.

5

Fig 2 UV absorption spectra of diclofenac sodium. 32

Fig 3 Calibration curve of diclofenac sodium in phosphate buffer pH 7.2 at 276 nm.

33

Fig 4 UV absorption spectra of diclofenac sodium in alginate matrix.

36

Fig 5 UV absorption spectra of diclofeance calcium. 36

Fig 6 UV absorption spectra of diclofeance calcium in alginate matrix.

37

Fig 7 Comparative dissolution profile of formulation F1 and F2. 40




Fig 11 Comparative dissolution profile of marketed conventional tablets and F1 and F2.

52

Fig 12 Comparative dissolution profile of marketed sustained release tablets and F2 and F4.

52

Fig 13 Comparative dissolution profile of F3 and F4. 54

Fig 14 Comparative dissolution profile of F5 and F6. 54

Fig 15 IR spectra of sodium alginate. 55

Fig 16 IR spectra of diclofenac sodium. 56

Fig 17 IR spectra of diclofenac sodium in alginate matrix. 57

Fig 18 IR spectra of diclofenac calcium. 58

Fig 19 IR spectra of diclofenac calcium in alginate matrix. 59

Fig 20 Higuchi plot of F3 61




v

List of Abbreviations

% = Percent

°C = Degree Celsius

gm = Gram

ml = milliliter

nm = nanometer

mg = Milligram

Cm = Centimeter

min = Minutes

hrs = Hours

rpm = Rotations per minute

w/v = Weight per volume

v/v = Volume per volume

w/w = Weight by weight

λ max = Absorption maxima

µg/ml = Microgram per milliliter

conc = Concentration

SD = Standard deviation

DF = Dilution factor

Ch. 1Introduction

Department of Pharmaceutics, N.G.S.M.I.P.S, Mangalore. 1

INTRODUCTION

Controlled release drug delivery systems:1

For many decades treatment of an acute disease or chronic illness has been

accomplished by using various pharmaceutical dosage forms like tablets,

suppositories, ointments, etc. To maintain the drug concentration within the

therapeutically effective range, it is often necessary to take the dosage form several

times a day which may result in significant fluctuations in drug blood levels.

Recently several technical advancements have been made which are capable

of controlling the rate of dug delivery, sustaining the duration of therapeutic activity

and/or targeting the delivery of drug to a tissue. There are a variety of drug

modifications and dosage forms which are attempted to control the time course and

specificity of dugs in the body.

They are identified by various names such as controlled release/ sustained

release/ prolonged release and timed release etc.

The term-controlled release implies a predictability and reproducibility in the

release kinetics. This means that the release of drugs from the delivery systems

proceeds at a rate profile that is not only predictable kinetically but also reproducible

from one unit to another.

In general controlled drug delivery attempts to:2

1) Sustain drug action at a predetermined rate by maintaining a relatively

constant, effective drug level in the body with concomitant minimization of

undesirable side effects associated with a saw tooth kinetic pattern.

2) Localize drug action by spatial placement of a controlled release system

adjacent to or in the diseased organ or tissue.

Ch. 1Introduction


3) Targeting drug by using carriers or chemicals and to a particular target cell

type.

Rationale for Controlled Drug Delivery:2

Basic rationale for Controlled Drug Delivery is to alter the pharmacokinetics

and pharmacodynamics of pharmacologically active moieties by using novel drug

delivery systems or by modifying the molecular structure and/or physiological

parameters inherent in a selected route of administration. It is desirable that the

duration of action becomes more a design property of a rate-controlled dosage form

and less or not at all, a property of the drug molecules inherent kinetic properties.

Presently the majority of these systems are based on polymers that differ in

degree of erodability, swellability and sensitivity to the biological environment in

which they are placed5.

Matrix Tablets:3,4

Matrix technologies have often proven popular among the oral controlled drug

delivery technologies because of their simplicity, ease in manufacturing, high level of

reproducibility, stability of raw materials and dosage form, and ease of scale –up and

process validation. Technological advancement in the area of matrix formulation

have made controlled release product development much easier than before, and

improved upon the feasibility of delivering a wide variety of drugs with different

physicochemical and biopharmaceutical properties. This is reflected by the large

number of patents filed each year and by the commercial success of a number of

novel drug delivery system based on matrix technologies.

Matrix based delivery technologies have steadily matured from delivering

drugs by first order or square root of time release kinetics to much more complex and

customized release patterns. In order to achieve linear or zero order release, various

Ch. 1Introduction


strategies that seek to manipulate tablet geometry, polymer variables, and formulation

aspects have been applied. Various drug, polymer and formulation related factors,

which influence the in-situ formation of polymeric gel layer/drug depletion zone and

its characteristics as a function of time, determine the drug release from matrix

systems.

One of the least complicated approaches in the manufacture of sustained

release dosage form involves the direct compression of blends of drug, retardant

material (lipophilic or hydrophilic) and additives to form a tablet in which drug is

embedded in a matrix core of retardant.

Table 1:List of retardant material used in matrix tablet.

Matrix characteristics Material

Insoluble, inert Polyethylene, Polyvinyl chloride, Methyl

acrylate-methacrylate co-polymer, Ethyl

cellulose

Insoluble, erodible Carnauba wax

stearyl alcohol

stearic acid

polyethylene glycol

Castor wax

polyethylene glycol monostearate

Trigrycerides.

Hydrophilic Methyl cellulose (400 cps, 4000 cps)

Hydroxy ethyl cellulose, Hydroxy

propylmethyl cellulose (60HG, 90HG, 25

CPS, 40000 CPS, 15000 CPS), Sodium

carboxy methyl cellulose, Carboxy

polymethylene, Sodium alginate

Ch. 1Introduction


Tablets prepared from the first class of polymers are designed to be ingested

intact and do not break apart in the GI tract. The rate- limiting step in controlling

release from these formulations is liquid penetration into the matrix unless channeling

(wetting) agents are included to promote penetration of the polymer matrix by water,

which allows drug dissolution and diffusion from the channels, created in the matrix.

Tablets prepared from the second class of materials control the release of drug

through both pore diffusion and erosion. Release characteristics are therefore more

sensitive to digestive fluid composition than to totally insoluble polymer matrix.

Third group of matrix formers represents non-digestible materials that form

gels in situ. Drug release is controlled by penetration of water through a gel layer

produced by hydration of the polymer and diffusion of drug through the swollen,

hydrated matrix in addition to the erosion of the gelled layer. The extent to which

diffusion or erosion controls the release, depends on the polymer selected for the

formulation as well as on the drug polymer ratio.

Alginates are established among the most versatile biopolymers, used in the

wide range of application. Hydrocolloids like alginate play a significant role in the

design of controlled release product. At low pH hydration of alginic acid leads to the

formation of high viscosity “acid gel”. Alginate is also readily gelled in the presence

of divalent cation such as calcium ion. Dried sodium alginate reswells creating a

diffusion barrier and thereby decreasing the migration of molecules (e.g.: -drugs).

Ability of alginate to form two types of gel dependant on pH i.e., an acid gel and an

ionotropic gel, gives the polymer unique properties compared to neutral

macromolecules.6

Ch. 1Introduction


Matrix Diffusion Controlled Drug Delivery System:7

Drug dispersion in the polymer matrix is accomplished by (i) blending the

dose of finely powdered or ground drug particles with a viscous liquid polymer or a

semisolid polymer, followed by cross-linking of polymer chains or (ii) by mixing

drug solids with a melted polymer at an elevated temperature. The resultant drug-

polymer dispersion is then molded or extruded to form devices of various sizes and

shape.

Rate of drug release from matrix diffusion controlled drug delivery systems is

time dependent as defined by

= -

A is the loading dose of drug initially dispersed in polymer matrix.

CR is drug solubility in polymer.

Dp is diffusivity of drug molecules in the polymer matrix.

dQ dt

A CR DP 1/2

2t

Ch. 1Introduction


Fig 1: Release of drug from matrix diffusion controlled drug delivery system with

drug reservoir exist as homogenous dispersion in a) lipophilic, non-swellable polymer

matrix with growing thickness of drug depletion zone or b) Hydrophillic, swellable

polymer matrix with growing gel.

SALT FORM OF THE DRUG AND ITS ABSORPTION:8,9

Salt formation is frequently performed on weak acidic or basic drugs because

it is relatively simple chemical manipulation, which may alter the physicochemical,

formulation, biopharmaceutical, and therapeutic properties of a drug without

modifying the basic chemical structure.

Ideal characteristics of a salt are chemically stable, non-hygroscopic, present

no processing problems, dissolves quickly from solid dosage forms or dissolves

slowly if it is formed with the intent to delay dissolution and exhibits good

bioavailabilty.

Drugs that are administered orally and are sensitive to acid environments

benefits from forming salts which are poorly soluble in acidic condition.

Bioavailability of magnesium and calcium salts of indomethacin was

compared in rats for indomethacin. Mean plasma levels after single oral dose of salts

were significantly higher and the area under the plasma curve after multiple oral

dosing of salts was significantly higher than the administration of indomethacin free

acid.

Calcium salts of drugs can results in higher melting points and perhaps lower

solubility and higher chemical stability. Calcium salts are usually less hygroscopic

than sodium salts and exhibit a characteristic negative heat of solution.

Potassium salt of penicillin yields a higher peak concentration of antibiotic in

plasma than does the free acid. Oral administration of the calcium salt yields peak

plasma levels intermediary to those of sodium salt and free acid.

Ch. 2 Objectives


Need for the study:

Diclofenac sodium is an non-steroidal anti- inflammatory drug (NSAID), used

for rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, acute musculoskeletal

injury and dysmenorrhea. It is administered in dose of 75-100mg per day in 3-4

divided doses. It has short biological half life of 1-2 hours and is eliminated rapidly.

So multiple dosing is required to maintain required therapeutic level. Frequent

administration results in peaks and trough in drug blood level leading to erractic

plasma level.

Besides this most frequent side effects occurring with diclofenac are gastro

intestinal disturbances, peptic ulceration and gastrointestinal bleeding, which may be

appreciable on long term administration with multiple dosing. Based on these

drawbacks, it is necessary to develop sustained release formulation. There has been no

study that investigates the sustained release property of calcium salts of diclofenac.

The poor solubility of calcium salt in general, by itself would impart sustained release

character of molecule.

Alginate has been chosen as matrix forming material for formulating sustained

release dosage form, as it was reported that the release of sodium salt of diclofenac

reduces drastically from alginate due to complex mechanisms. Hence the present

study was undertaken to study the sustained release behaviour of diclofenac from

alginate.

In the present work an attempt was made to prepare calcium salts of

diclofenac and evaluate its release property from conventional and matrix tablets and

to compare it with release study of diclofenac sodium from conventional and matrix

tablets.

Ch. 2 Objectives


× Objective of the study

The objectives of the present present study are to:-

1. Prepare calcium salt of diclofenac.

2. Analyze qualitatively the formation of diclofenac calcium salt.

3. Formulate conventional tablets of calcium diclofenac and sodium diclofenac.

4. Prepare matrix tablets of above salts with sodium alginate.

5. Evaluation of the above prepared tablets.

Eg: Shape, thickness, weight variation, friability, hardness and tablet content.

6. Evaluate the in-vitro drug release study.

7. Evaluate the Stability studies.

8. Comparative study of drug release pattern for both conventional and matrix

tablets of diclofenac sodium and diclofenac calcium with marketed sustained

release tablets of diclofenac as well as conventional tablets.

Ch. 3 Review of Literature


REVIEW OF LITERATURE

Drug profile:10,11,12,13

Diclofenac sodium:

Molecular formula:- C14H10O2Cl2N Na

Molecular weight: - 318.13

Chemical name :-2-[(2, 6-dichlorophenyl)-amino] phenyl acetate.

Description: - white to slightly yellowish crystalline powder, slightly hygroscopic.

Solubility:-

Freely soluble in methanol, soluble in ethanol (95%), sparingly soluble in

water and glacial acetic acid, practically insoluble in ether, chloroform and toluene.

Melting point :-

Melts at about 280°c with decomposition.

Standards :-

Diclofenac sodium contains not less than 98.5% and not more than 101.0% of

C14H10Cl2N NaO2, calculated with reference to the dried sample.

Pharmacological properties:-

Diclofenac has analgesic, antipyretic and anti- inflammatory activities. It is a

potent relatively non-selective cyclooxygenase inhibitor and its potency is greater

than that of indomethacin naproxen, or several other agents. In addition, diclofenac

appears to reduce intracellular concentration of free arachidonate in leucocytes,

perhaps by altering the release or uptake of the fatty acid.

Pharmacokinetics:-

Diclofenac is rapidly and completely absorbed after oral administration; peak

concentrations in plasma are reached within 2-3 hours. Administration with food



slows the rate but does not alter the extent of absorption. There is a substantial first-

pass effect, such that only about 50% of diclofenac is available systemically. The

drug is extensively binds to plasma proteins (99%) and its half- life in plasma is 1-2

hours. Diclofenac accumulates in synovial fluid after oral administration, which may

explain the duration of therapeutic effect that is considerably longer than the plasma

half- life. Diclofenac is distributed into breast milk but the amount is considered by

some authorities is to be too small to be harmful to breast fed infants.

Metabolism:-

Diclofenac is metabolized in Liver by a cytochrome P-450 isozyme of the

CYP2C sub family to 4-hydroxy diclofenac, the principal metabolite and other

hydroxylated forms; after glucuronidation and sulfation. The metabolites are excreted

in the urine (65%) and bile (35%). Biliary clearance can account for up to 30% of

total clearance.

Therapeutic uses:-

Diclofenac sodium is used for the long-term symptomatic treatment of

rheumatoid arthritis, osteoarthritis and ankylosing spondylitis. Also useful for short-

term treatment of acute musculoskeletal injury, acute painful shoulder (bicipital

tendinitis and subdeltoid bruisitis), post-operative pain and dysmenorrhoea.

Adverse Effects:-

Occur in approximately 20% of patients and include gastrointestinal distress,

gastrointestinal bleeding and gastric ulceration. Elevation of hepatic amino-

transferase activities in plasma occurs in about 14% of patients. Other untoward

responses to diclofenac include CNS effects, skin rashes, allergic reaction, fluid

retention and edema, and rarely impairment of renal function.

Dosage:-

75-150mg daily in divided doses.



Polymer profile:

Sodium alginate:14

Synonym: Manugel, Sodium polymannuronate,

Chemical name : - Sodium alginate.

Functional category :

Stabilising agent, suspending agent, tablet and capsule disintegrant, tablet

binder and viscosity increasing agent.

Application in pharmaceutical formulation:

Sodium alginate is mainly used in a variety of oral and topical pharmaceutical

formulation. In tablet formulation, sodium alginate can also be used in preparation of

sustained release oral formulation since it can delay the dissolution of a drug from the

tablets.

Description: -

Sodium alginate occurs as an odorless and tasteless, white to pale yellowish

brown colored powder.

Solubility:-

Practically insoluble in ethanol, ether and ethanol/water mixtures in which the

ethanol content is greater than 30%. Also practically insoluble in other organic

solvents and acids in which the pH of the resultant solution is less than 3. It is readily

soluble in water forming a viscous colloidal solution.

Viscosity: -

A 1% w/v aqueous solution at 20° will have a viscosity of 20-400cps.

Viscosity varies depending on concentration, pH, temperature or presence of metal

ions. Above pH 10, viscosity reduces.



Stability and storage: -

Sodium alginate is a hygroscopic material. It is stable if stored at relatively

low humidities and cool temperature. Aqueous solution of sodium alginate is most

stable between pH 4-10. Below pH 3, alginic acid gets precipitated. Sodium alginate

is susceptible to microbial spoilage on storage, which may affect solution viscosity.

Safety: -

It is non-toxic and non- irritant material.



Ø Bodmier et al (1989)15 studied the agglomeration of poorly water soluble drugs

like ibuprofen, indomethacin, micronised griseofulvin, sulphadiazine and

tolbutamide by dispersing each drug in chitosan or sodium alginate and then

dropping the dispersion into a solution of calcium chloride. The droplets

instantaneously formed gelled spheres by ionotropic gelation. The ionic character

of the polymer resulted in pH dependant disintegration of the beads like chitosan

disintegrated in acidic condition (0.1N HCl) and sodium alginate in intestinal pH.

Ø S. Malamataris and D. Ganderton (1991)16 studied the in-vitro release from the

matrix comprising hydrophobic and hydrophilic (gel- forming) components

containing three non-steroidal anti- inflammatory agents with different solubility

and wettability (indomethacin, ibuprofen and diclofenac sodium). Release rate

decreased with drug/matrix ratio for wettable, soluble diclofenac but increased

with indomethacin and ibuprofen. The release rate changes are explained on the

basis of the interaction between the gel and other matrix components in the

presence of water.

Ø Bain J. C et al (1991)17 investigated the in-vitro release characteristic of

diclofenac sodium from sustained release wax matrix and hydrogel tablet. The

wax matrix tablets exhibited classic diffusion controlled release of diclofenac

down tortuous pores and were relatively independent of rotational speeds when

the tablets were free from abrasion. The hydrogel tablet exhibited near zero order

release where a dynamic equilibrium exists between rate of swelling and erosion

up to a point where high rotation speeds upset this equilibrium by increasing

erosion.

Ø Lin S Y et al (1995)18 prepared and evaluated sodium diclofenac controlled

release tablets by using dibasic calcium phosphate (DCP) in different weight



ratios with or without biosoluble polymer (acrylic based resin) in distilled water

and in a medium with changing pH. The results indicate that the amount of

sodium diclofenac released from the compact was dependent on the amount of

drug and DCP used in the compact, and was also controlled by amount of

bisoluble polymer added. The tablet with a 1:2 weight ratio of sodium diclofenac

to DCP exhibited a sustained release behavior, similar to commercial sustained

release products (Voltaren SR – 100 and Grofenac retard), but a lower release rate

was found as compared to the commercial products.

Ø Alison C. Hodsdon et al (1995)19 studied the effect of pH and drug solubility on

the release kinetics of sodium alginate matrices. Release of a highly soluble model

drug, chloramphenicol maleate was significantly faster in simulated gastric fluid

(SGF) than in simulated intestinal fluid (SIF), whereas the opposite effect was

observed for hydrochlorthiazide, a drug of poor solubility. These results could be

explained in terms of the internal microscopic structure of the hydrated surface

layer formed on matrix hydration and by different hydration kinetics of the

polymer in these two media. Cryogenic electron microscopy revealed the hydrated

surface layer formed by alginate matrices in SGF to be particulate and porous in

nature, in contrast to highly hydrated continuous gel layer formed in SIF. Drug

release mechanisms were discussed with respect to drug solubility and the

structure and properties of the surface layers formed by alginate matrices when

hydrated in different pH media.

Ø Liu C. H. et al (1995)20 studied five controlled release matrix tablet formulation

containing diclofenac sodium and HPMC. They were prepared and evaluated in-

vitro and in 6 healthy male subjects who received the oral formulation in a cross-

over design. All the five formulations prolonged drug release in-vitro. The main



factors controlling release were the higher the concentration of high viscosity

grade polymer, the slower the release rate. There were in-vitro correlations

between the plasma Cmax, area under the plasma drug concentration time curve

and time for 50 to 80% drug to be released.

Ø Kikuchi et al (1997)21 prepared calcium alginate gel beads for pulsed dextran

release. They found that sodium alginate forms a hydrogel upon contact with

calcium ions in aqueous solution due to physical cross-linking (chelation) between

the carbohydrate anions of glucuronate units in alginate and the calcium ions.

Alginate disintegration (dissolution) in phosphate buffered saline solution (pH 7.4)

occurs completely in a short time period after a certain lag time. Calcium ions

release from the alginate gels is believed to be an influential factor in alginate

dissolution. The larger the diameters of the alginate beads, the slower the observed

release time onset. Furthermore, dextran release was in a pulsatile fashion using

calcium-alginate gel beads by mixing different bead sizes. These results indicate

that pulsatile release of macromolecular drugs such as proteins and peptides could

be achieved using calcium alginate beads.

Ø Takagi I et. al., (1997)22 studied the possibility of producing calcium induced

alginate beads as a vehicle for liposomes was explored. The liposomes were well

maintained within both fully cured and washed beads. The liposome release from

the fully cured beads was much slower than that from the corresponding washed

beads in a pH 7.4 releasing medium. The greater the liposome loading, the faster

the release of the vesicles. The liposome release was investigated in terms of

liposome loading, swelling of the gel body, calcium discharge and gel erosion

using washed beads. The liposome loading did not affect the bead erosion or

calcium discharge but did the initial swelling ratio and liposome release. The



result suggests that the loaded liposomes are not uniformly distributed in the bead

but are rather gradually concentrated to the centre.

Ø Takka S. et al., (1998)23 prepared and studied the release rate of nicardipine HCl

from various alginate gel beads. The formulations were prepared by using

factorial design. The effect of drug: polymer weight ratio, calcium chloride and

sodium alginate concentration on the time for 50% of the drug release and the

entrapment efficiency were evaluated with analysis of variance. The mean particle

size and the swelling ratio of the beads were determined. The in-vitro release

studies were carried out by flow through cell apparatus in different media. Release

of nicardipine was extended with the alginate beads, which were prepared in a

ratio of 1:1 (drug: polymer). The release of drug from alginate beads took place

both by diffusion through the swollen matrix and relaxation of polymer at pH 1.2-

4.5. The release was due to diffusion and erosion mechanism at pH 7-7.5.

Ø M.J. Fernandez-Hervas et al., (1998)36 formulated alginate beads containing

diclofenac hydroxyethylpyrolidine with either eudragit or chitosan in order to

achieve an enteric formulation. The examination of fractured beads revealed an

internal void in the eudragit-alginate beads. In contrast, a dense homogeneous

internal structure was observed in the chitosan-alginate beads due to

interpolymeric complex. An interaction between chitosan and drug was also

observed. Under conditions mimicking those in the stomach, a small amount of

drug was released. The alginate chitosan beads showed release behaviour

dependent on pH value and alginate chitosan ratio.

Ø Vines Pillay et al., (1999)34 investigated the cross- linking of sodium alginate, low

methoxylated pectin and their novel binary mixture with calcium ions through

ionotropic gelation to pelletize the model drug, diclofenac sodium using



“environmentally benign” solvents and processing techniques. Cross- linked

pellets of the above polymers in 2% (w/v) aqueous calcium chloride solution were

prepared and evaluated for their structural and release behavior. Negligible drug

release occurred in pH 1-4. However, rate of drug release in pH 6.6 ranged from

rapid to slow but always in a controlled manner.

Ø Anandrao R Kulkarni et al., (1999)35 prepared controlled release sodium alginate

(Na-Alg) beads containing diclofenac sodium (DS) by precipitation of Na-Alg in

alcohol followed by cross-linking with glutaraldehyde (GA) in acidic medium.

Beads were optimized by considering the percentage entrapment efficiency,

swelling capacity of beads in water and their release data. The beads produced at

higher temperatures and longer times of exposure to the cross- linking agent have

shown the lower entrapment efficiency, but extended release of DS from the

beads. The scanning electron microsopic studies indicated nonporous smooth

surfaces and the differential scanning calorimetric data indicated the molecular

level dispersion of the drugs in the beads.

Ø Paolo Giunchedi et al., (2000)24 investigated the use of sodium alginate for the

preparation of hydrophilic matrix tablets intended for prolonged drug release

using ketoprofen. Matrix tablets were prepared by direct compression using

sodium alginate, calcium gluconate and hydroxylpropylmethylcellulose (HPMC)

in different combinations and ratios. Matrices consisting of sodium alginate alone

or in combination with HPMC gave a prolonged drug release at a fairly constant

rate. Incorporation of different ratios of calcium gluconate leads to an

enhancement of the release rate from the matrices and loss of constant release rate

of the drug.



Ø Bravo S A. et al., (2002)25 prepared uncoated HPMC matrix tablets and evaluate

the relationship and influence of different content levels of microcrystalline

cellulose (MCC), starch and lactose in order to achieve zero order release of

diclofenac sodium and found that the release of diclofenac sodium and found that

the release of diclofenac sodium was influenced by the presence of MCC and by

different concentration of starch and lactose. The release of drug from HPMC

matrix tablets was prolonged when compared to conventional diclofenac tablets.

Ø M.L. Gonzalez-Rodriguez et al., (2002)37 prepared alginate chitosan particles by

ionic gelation (Ca2+ and Al3+) for the sodium diclofenac release. The systems were

characterized by electron microscopy and differential scanning calorimetry. The

ability to release the active substance was examined as a function of some

technological parameters and pH of dissolution medium. The release of sodium

diclofenac is prevented at acidic pH, while is complete in a few minutes when pH

is raised up to 6.4 and 7.2. The alginate/chitosan ration and the nature of the

gellifying cation allow a control of the release rate of drug.

Ø AL- Taani B M. et al., (2003)26 studied the effect of microenvironment pH on the

release pattern of diclofenac sodium from pH dependant swellable and erodible –

buffered matrices and found that the rate of drug release is increased with the

increase of the micro-environment pH of matrices but the release pattern of drug

was unaffected.

Ø Maria Luisa Gonzalez – Rodriguez et al., (2003)27 designed delivery system

consisted in a polymeric matrix tablet containing a drug central core for obtaining

a time controlled release profile characterized by an initial phase of lag time

followed by a controlled release phase according to zero order kinetics. Eudragit

RS 100 was used as inert polymeric matrix for the core coating, mixed with



sodium chloride and emdex as channeling agent. Lag time increased with

decreasing the channeling agent particle size. Formulation containing sodium

chloride always showed longer lag times than corresponding with emdex and were

more effective in providing prolonged zero-order release periods. By varying the

sodium chloride/eudragit w/w ratio it was possible to suitably modulate the length

of both the lag time (for achieving colonic targeting) and zero order release

phases.

Ø Holte A. et al., (2003)28 investigated the release of acetyl salicylic acid from

directly compressed alginate tablets. The effect of the amount and type of alginate

on the drug release rate was evaluated in different formulations. Four different

grades of alginates were used. Drug release sustained up to 16 hour was achieved

using sodium alginate in combination with dibasic calcium phosphate.

Ø S. S. Biju et al., (2004)29 formulate novel enteric micro-capsules for improved

delivery to the intestine using the polymers cellulose acetate phthalate (CAP) and

ethyl cellulose (EC) of diclofenac sodium. In-vitro release study was carried out

in simulated gastric fluid for first 2 hour and simulated intestinal fluid for next 6

hour. Best formulation that contains CAP and EC in the concentration of 10:90 at

1:1.5 drug: polymer ratio was further evaluated using in-vivo for its

pharmacodynamic efficacy and ulcerogenicity. In addition to sustained and

uniform release of drug, the formulation showed better anti- inflammatory activity

than marketed formulation and retarded drug release in the gastric medium. The

biological examination of incised stomach showed no histological alterations in

terms of mucous surface cells and glands.

Ø Ali Nokhodchi et al., (2004)30 investigated matrices of calcium alginate or

aluminum alginate as possible controlled release system for drugs. Objective of



the study was to sustain the release of theophylline from alginate matrices using

different concentration of aluminum chloride and calcium chloride in presence

and absence of HPMC. Tablets containing differing concentration of aluminum

and calcium chloride were produced & the release rate of theophylline was tested.

Increasing the amount of aluminum chloride, decreased the release of theopylline

indicating a significant effect of aluminum ions on a reduction in the release rate

of theophylline from alginate matrices. In case of matrices containing different

concentration of calcium ions, as the concentration of calcium chloride increases,

the release rate increased to an optimum then declined after this. This was due to

insufficient calcium ions being available to cross-link with the sodium alginate to

form an insoluble gel. The results also showed that the presence of HPMC cause

a reduction in release rate of theophylline from alginate matrices. Whereas, in case

of alginate matrices containing aluminium chloride the release rate of theophylline

increased in presence of HPMC.

Ø Bravo S. A. et al., (2004)31 investigated the delivery of drugs by a process of

continuous swelling of the polymeric carrier for oral sustained release systems.

The goal of the study was to evaluate the effects of HPMC and carboxy polymer

(carbopol 934) on the release behaviour of diclofenac sodium (DS) from a

swellable matrix tablet system. The influence of the polymer content, the polymer

ratio, the polymeric swelling behavior and the pH changes on the release rate of

DS was investigated. There was no significant difference in drug release when

total polymer concentration was 10%. When the tablets were formulated having

20% or 30% of HPMC/cabomer, it was observed that a more rapid release of DS

occurred as carboxy polymer ratio within the matrices increased. The dissolution

studies demonstrated that the combination of these two polymeric matrix formers



resulted in near zero-order release rate of DS. The DS release from all these

matrix tablets was pH dependant.

Ø Ayhan Savaser et al., (2005)32 studied the effect of formulation variables on the

release profile of diclofenac sodium from hydroxypropylmethylcellulose (HPMC)

and chitosan matrix tablets. In-vitro studies showed that 20% HPMC contained

sustained release formulation with direct compression method is the optimum

formulation due to its better targeting profile in terms of release. This formulation

also exhibits the best-fitted formulation in zero order kinetics.

Ø Satit Puttipipathachorn et al., (2005)33 prepared diclofenac calcium-alginate

(DCA) beads with different amounts of sodium starch glycolate (SSG) or

magnesium aluminium silicate (MAS) using ionotropic gelation method.

Complex formation of sodium alginate and SSG or MAS in calcium alginate

beads was revealed using FT-IR spectroscopy. Thermal behavior of SSG- DCA

and MAS-DCA beads was similar to the control beads. Both additives can

improve the entrapment efficiency of DCA beads. The swelling and water uptake

of the beads depend on the properties of incorporated additives. Release kinetics

of the beads was swelling controlled mechanism in phosphate buffer pH 6.8, while

that in distilled water fo llowed Higuchi’s model.

Ch. 4 Methodology


MATERIALS

Drug

Diclofenac sodium J.B. Chemicals. Mumbai

Polymers

Sodium alginate Glenmark Pharmaceuticals Ltd.

Chemicals

Calcium chloride E.merck, Mumbai

Sodium hydroxide Merck, Mumbai

Potassium dihydrogen phosphate Genuine chemical Co., Mumbai

Oxalic acid Nice chemicals, Cochin

All the other chemicals used were of analytical reagent grade. (A. R. grade)

Eqiupments

UV/visible spectrophotometer Jasco V-530

Desiccator Terrasons

Hot air oven Kemi, KUHS-2

Electronic balance Ohasus Corporation, Japan

Tablet dissolution tester USP(XXIII) Electrolab

Ch. 4 Methodology


METHODOLOGY

Preparation of 0.2M potassium dihydrogen phosphate solution: -

27.218gm of potassium dihydrogen phosphate was dissolved in distilled water

and diluted with distilled water to 1000ml.

Preparation of 0.2M sodium hydroxide solution: -

Dissolved 8gm of sodium hydroxide in distilled water and diluted with

distilled water up to 1000ml.

Preparation of phosphate buffer pH 7.2: -

Placed 50.0ml of 0.2M potassium dihydrogen phosphate in a 200ml

volumetric flask, and 34.7ml of 0.2M sodium hydroxide solution was added and

distilled water was added up to the volume to make 200ml.

Preparation of standard stock solution in phosphate buffer pH 7.2: -

100mg of pure drug diclofenac sodium was accurately weighed and

transferred into a 100ml volumetric flask. Small quantity of buffer was added and

dissolved. Volume was made up to 100ml using phosphate buffer pH 7.2. (Stock

solution -1000µg/ml of drug).

4.1. Scanning of diclofenac sodium:

From the above stock solution suitable quantity was withdrawn and the

volume was made up to 100ml with phosphate buffer to get a concentration of

10µg/ml and the sample was scanned between 250-350nm as shown in fig 2.

4.2. Preparation of calibration curve: -

From the standard stock solution, secondary stock solution was prepared by

diluting the primary stock solution ten times so that the secondary stock solution with

a concentration of 100µg/ml. From this secondary stock solution, aliquots of 0.5ml to

2.5ml were transferred into a series of 10ml volumetric flasks and final volume was

Ch. 4 Methodology


made up with buffer to give the concentration ranging from 5µg/ml to 25µg/ml. The

absorbance of these solutions was measured against a phosphate buffer pH 7.2 as a

blank in UV/visible spectrophotometer at 276nm. Average of three determinations

was taken. The data and the standard graph are shown in table 5 and fig 3

respectively.

4.3. Preparation of calcium salts of diclofenac: -

1gm of diclofenac sodium was dissolved in 100ml of distilled water. 7.5

mmoles of calcium chloride solution was prepared and added to the above solution

drop wise till the complete precipitation formed. Then the precipitate was filtered,

washed with distilled water and dried in hot air oven.

4.3.1 Confirmatory tests for the presence of calcium salts of diclofenac: -

i UV scanning : - The sample was dissolved in phosphate buffer pH 7.2 and

scanned between 200-300nm.

ii Calcium oxalate test38: - The salt was dissolved in water and added to

oxalic acid solution. There should be a formation of white precipitate of

calcium oxalate.

iii Flame test38: - The salt was dispersed in 0.1N HCl solution and was held

over Bunsen flame.

4.4. Solubility determination:

The solubility measurements of diclofenac sodium and diclofenac calcium

were investigated by adding an excess of drugs to the distilled water. After the

equilibrium was reached, the drug concentration in the supernatant was determined

spectrophotometrically. The results of the solubility measurements are given in

table 6.

Ch. 4 Methodology


4.5. Preparation of conventional tablets of Diclofenac sodium and Calcium salts

of diclofenac: -

Tablets were prepared by direct compression method. All the ingredients were

blended together in a bottle by tumbling action. Sodium starch glycolate was used as

disintegrant, lactose as diluent and magnesium stearate as lubricant. Powder mass was

compressed into tablets using a cadmach single punch tablet press with 6mm punch

and die set. Each tablet contains 100mg of diclofenac. Composition of each tablet is

given in table 2.

Table 2: Composition of conventional tablet

Quantity used for each tablet (mg) Ingredients

F1 F2

Drug 50 50

Lactose 150 150

Sodium Starch Glycolate 10 10

Magnesium Stearte 4 4

Total Weight 214 214

F1 – Diclofenac Sodium

F2 – Diclofenac Calcium

4.6. Preparation of alginate matrix of diclofenac sodium and diclofenac calcium.

Sodium alginate (2gm) was dissolved in distilled water (100ml). Drug (1gm)

was dispersed in specified volume of 2% sodium alginate solution as specified in

table 3. To the drug polymer dispersion 2% calcium chloride solution was added drop

wise with gentle stirring to form the gel matrix. The gel matrix was filtered, washed

Ch. 4 Methodology


with water and dried at an ambient condition. Then pulverized and passed through

sieve.

Table 3: Quantity of drug and polymer used in preparation of matrix

Type of Matrix Drug :

Polymer

Amount of Drug and Polymer

used

1:1

1 gm of diclofenac sodium and

50 ml of sodium alginate (2%)

solution (which contains 1 gm

sodium alginate) Diclofenac sodium : Sodium Alginate

1:2

1 gm of diclofenac sodium and



sodium alginate)

1:1

1 gm of diclofenac calcium and



sodium alginate) Diclofenac calcium : Sodium Alginate

1:2

1 gm of diclofenac calcium and



sodium alginate)

4.6.1 Evaluation of the matrix: -

The prepared matrix was evaluated for the percentage yield, percentage

entrapment efficiency of the drug and drug content.

4.6.1.1 Percentage yield of the matrix: -

The percentage yield of the matrix was found out based on the dry weight of

the drug and polymer taken and the final weight of the matrix obtained. The results

are given in the table 7.

Ch. 4 Methodology


4.6.1.2 Drug content analysis of the matrix: -

The amount of drug entrapped in alginate matrix was estimated by transferring

accurately weighed 100mg of matrix in 100ml volumetric flask. Matrix was dissolved

and volume was made up to100ml with phosphate buffer pH 7.2. The solution was

diluted suitably and the absorbance of the diluted solution was determined using UV

spectrophotometer at 276nm. The amount of drug entrapped in the matrix was

calculated from dilution. The results are given in table 8.

4.6.1.3 UV scanning: -

The UV scanning of the solution of matrix containing diclofenac sodium and

diclofenac calcium in phosphate buffer pH 7.2 was done to verify the presence of

drug in matrix and also to check whether there is any interaction of the drug with

polymer. The results are shown in fig 3 and 5 respectively.

4.6.2 Preparation of matrix tablets: -

Matrix tablets were prepared with the drug: polymer ratio of 1:1 and 1:2. The

matrix was passed through sieve 20. Magnesium stearate was added as a lubricant.

Quantity of matrix equivalent to 100mg of drug was taken and mixed with

magnesium stearate in a bottle by tumbling action. Powder mass was compressed into

tablet using a cadmach single punch tablet press with 6mm punch and die set. Each

tablet contains 100mg of diclofenac. Composition of each tablet is given in table 4.

Table 4: Composition of diclofenac matrix tablet

Quantity used for each tablet, (mg) F 3 F 4 F 5 F 6 Ingredients 1:1 1:2 1:1 1:2

Diclofenac Sodium matrix 242 400 - -

Diclofenac Calcium matrix - - 214 355

Magnesium Stearte 2 4 2 3.5

Total Weight 246 404 216 358.5

Ch. 4 Methodology


4.7. Evaluation of tablets:39

i. Shape of tablets:-

Compressed tablets were examined physically for the shape of the tablet.

ii. Thickness: -

The thickness of tablet was determined with the help of vernier calipers. The

thickness variation was allowed in the range of + 5% of the size of the tablet. The

results are given in table9.

iii. Hardness:-

Hardness indicates the ability of the tablet to withstand mechanical shocks

while handling. The hardness of the tablets was determined using Monsanto hardness

tester. It is expressed in Kg/cm2. 5 tablets were randomly picked and hardness was

determined. The results are given in table9.

iv. Friability:-

Friability of the tablets was determined using Roche Friabilator. It is

expressed in percentage (%). Ten tablets were initially weighed (Winitial) and

transferred into friabilator. The friabilator was operated at 25 rpm for 4 minutes or

run up to 100 revolutions. The tablets were weighed again (Wfinal). The % friability

was then calculated by-

% Friability of the tablets less than 1% is considered as acceptable.

The results are given in table 9

F= Winitial - Wfinal x 100

Winitial

Ch. 4 Methodology


v. Weight Variation Test:-

Ten tablets were selected randomly from each batch and weighed individually

to check for the weight variation. U.S. Pharmacopoeia allows a little variation in the

weight of a tablet. The results are given in table 9. The following percentage

deviation in weight variation is allowed.

Average weight of a tablet Percentage deviation

130 mg or less 10

> 130 mg and < 324 mg 7.5

324 mg or more 5

vi. Drug content in tablets:-

The tablet was triturated to form a fine powder and transferred to a 100 ml

volumetric flask and dissolved in phosphate buffer pH 7.2 and was made up to the

volume to get stock solution. 1ml of this stock solution was taken in a 100ml

volumetric flask and diluted with phosphate buffer pH 7.2 and made up to the volume.

The absorbance of this solution was measured at 276nm using UV spectrophotometer.

(Jasco V-530) The drug content was estimated from the absorbance obtained. The

results are shown in table 10.

4.8. In-vitro dissolution study:25

In-vitro dissolution study of the tablets was carried out in USP dissolution

apparatus type-II, using 900ml of phosphate buffer pH 7.2 as a release medium

maintained at 37+ 0.5° C with 50 rpm. 5 ml of samples was withdrawn at specified

interval and filtered and diluted with phosphate buffer pH 7.2 and assayed

spectrophotometrically at 276 nm. The equal volume of fresh medium was

immediately replaced to maintain the dissolution volume constant. The amount of

Ch. 4 Methodology


drug release at each time interval was calculated from the absorbance of the samples.

Three trials were carried out. The percentage drug release was calculated and this

was plotted against function of time to find out pattern of drug release. The results are

given in table 11 to 20 and figure 7 - 14.

4.9 IR studies:

The pure drug, polymer and its formulations were subjected to IR spectral

studies.

4.10 Comparison with marketed sustained and conventional product

The promising formulations of diclofenac were compared with marketed

products for drug release profile.

Details of marketed products

Voveran – 50: Diclofenac sodium – 50mg

Nac – 50: Diclofenac sodium – 50mg

Voveran – SR – 100: Diclofenac sodium – 100mg, Sustained Released Tablets

Divon – SR – 100: Diclofenac sodium – 100mg, Sustained Released Tablets

4.11 Curve fitting analysis:39,25,40

To analyse the mechanism of the drug release rate kinetics of all the

formulations, the data obtained were fitted into zero order release rate kinetics and

into Higuchi model.

4.11.1 Zero order release rate kinetics:

To study the zero order release kinetics the release data were fitted to the

following equation.

F=K.t

Where ‘F’ is the fraction of drug release,

‘K’ is the release rate constant, and

‘t’ is the release time.

Ch. 4 Methodology


4.11.2 Higuchi release model:

To study the Higuchi release kinetics, the release data were fitted to the

following equation,

F=K .t1/2

Where, ‘F’ is the amount of drug release,

‘K’ is the release rate constant, and

‘t’ is the release time.

The regression coefficients values are given in table 21 and 22.

4.12. Stability studies of the tablets:25

Stability of a formulation can be defined as the time from date of manufacture

of the formulation until its chemical or biological activity is not less than a

predetermined level of labeled potency and its physical characteristics have not

changed appreciably or deleteriously.

Formulation and the development of a pharmaceutical product is not complete

without proper stability analysis, carried out on it to assess the physical and chemical

stability and the safety.

A general methodology for predicting stability is accelerated stability analysis,

which subjects the material to elevated temperatures.

Accelerated stability Analysis:

Two tablets from all the batches were wrapped in an aluminum foil and were

subjected to different conditions (room temperature, at 45°C and at 60°C

temperature). The samples were observed regularly at an interval of two week and

the samples were analysed for the amount of the drug remaining, by procedure

described in drug content analysis in tablets by using UV spectrophotometer. The

stability of the tablets was determined from the obtained data. The results are given in

table 23 and 24.

Ch. 5Result and Discussion


5.1 UV Scanning:

The UV spectra for pure drug is shown in Fig. 2:

Fig.2: UV absorption spectra of diclofenac sodium.

The UV absorption spectra shows the absorption peak at 276nm, which corresponds

to the peak of pure drug diclofenac.

5.2 Calibration curve for diclofenac sodium:

The values of absorbance for the calibration curve of diclofenac sodium in

phosphate buffer pH 7.2 are given in Table 5.

Table 5: Standard calibration data of diclofenac sodium in phosphate

buffer pH 7.2

Sr.no. Concentration (µg/ml)

* Absorbance Standard deviation (+)

1 0 0 0

2 5 0.1571 0.0051

3 10 0.3304 0.0020

4 15 0.4952 0.0015

5 20 0.6941 0.0043

6 25 0.8210 0.0018

* Average of three determinations



C= K* A+B

C=Concentration of the sample

K=30.527

A=Absorbance

B=0.0512

Fig. 3: Calibration Curve of Diclofenac sodium in phosphate buffer pH 7.2 at

276 nm.

5.3 Preparation of calcium salts of diclofenac: -

Calcium salts of diclofenac were prepared by the procedure described in

methodology section.

5.3.1 Confirmatory test: -

1. UV scanning: -The ? max was found to be 275.8nm in pH 7.2 phosphate buffer.

(Fig. 5)

2. When the solution of diclofenac calcium was added to oxalic acid solution,

white precipitate of calcium oxalate was formed.



3. Flame test of diclofenac calcium gave a yellow-red color flame, which

indicated the presence of calcium.

5.4 Solubility determinations :

Solubility of diclofenac sodium was found to be 0.852mg/ml in distilled

water.

Solubility of diclofenac calcium was found to be 0.7466mg/ml in distilled water.

Table 6: Solubility of diclofenac sodium and diclofenac calcium in distilled

water.

Drug Solubility in distilled water

mg/ml

Diclofenac sodium 0.852

Diclofenac calcium 0.746

5.5 Evaluation of matrix: -

5.5.1 Percentage yield of the matrix: -

The percentage yield of diclofenac matrix with different drug to polymer ratio

is shown in the Table 7.

Table 7: Percentage yields of diclofenac in matrix of sodium alginate.

Formulation Drug to polymer ratio Percentage yield

1:1 89.5% Diclofenac sodium: sodium alginate

(DS:SA) 1:2 80.25%

1:1 82.5% Diclofenac calcium: sodium alginate

(DC:SA) 1:2 78.5%

In both the formulation, the yield was found to be highest in the case of lowest

drug to polymer ratio. The percentage yield of matrix range from 78.5% to 89.5%.



5.5.2. Estimation of drug content in the matrix: -

The drug content was estimated in the matrix and is shown in Table 8.

Table 8: Drug content in matrix.

Drug content

Formulation Ratio Theoretical

(mg)

Practical

(mg) Percentage drug content

1:1 50 41.35 82.70% DS: SA

1:2 33.33 25.022 75.07%

1:1 50 46.75 93.50% DC: SA

1:2 33.33 28.17 84.51%

The drug content in calcium alginate matrix was found to be ranging from

75% to 93%, in which diclofenac calcium matrix shows higher drug content while

diclofenac sodium matrix shows lower drug content. Probably during the washing

stage there is a loss of diclofenac sodium since it is better soluble in water compared

to diclofenac calcium.

5.5.3 UV scanning: -

The presence of peak at 276nm in the UV absorption spectrum of the prepared

matrix containing the drug (as shown in Fig 4 and 6) confirmed the presence of

diclofenac in matrix.



Fig. 4: UV absorption spectra of diclofenac sodium in alginate matrix

Fig. 5: UV absorption spectra of diclofenac calcium



Fig. 6: UV absorption spectra of diclofenac calcium in alginate matrix.

5.6 Evaluation of formulated tablets: -

5.6.1 Shape of the tablets:

Physical examination of tablets from each formulation found to be circular

shape with no cracks.

5.6.2 Thickness:

Thickness of all tablets was found to be within the limit of + 5% of size of the

tablet and was uniform in all the batches. The results are given in Table 9.

5.6.3 Hardness:

The measured hardness of the tablets of each formulation range between 5 to

7.5 Kg/cm2. This ensures the good handling characteristics of all the formulations.

The results are given in Table 9:

5.6.4 Weight variation:

The average percentage weight variation for all the formulations was shown in

Table 9. All the tablets passed weight variation test as the average percentage weight

variation remained within the pharmacopoeial limits.



5.6.5 Friability:

The percentage friability was less than 1% in all the formulation ensuring that

the tablets were mechanically stable. The results are given in Table 9:

Table 9: Physical properties of the tablets.

Formulations * Thickness (mm)

Hardness (kg/cm2)

Average % Weight Variation

% Friability

F2 3.20+0.075 5-6.5 1.232 0.373

F3 3.08+ 0.020 6-7 1.278 0.245

F1 3.42+0.040 5-6 1.159 0.372

F4 3.48+0.044 7-7.5 0.702 0.22

F5 3.44+0.054 6-7 1.689 0.317

F6 3.48+0.083 7-7.5 0.867 0.25

* Average of three determinations

5.6.6 Drug content in tablets: -

The amount of drug content in each tablet has been evaluated for all the six

formulation. From this study the drug content in all the tablets was found to be within

the specified limits (90% to 110%). This indicates that all the formulations of

diclofenac were passing the drug content uniformity. The values are given in

Table 10.

Table 10: Drug content of tablets.

Formulation * Absorbance Concentration (µg/ml) % Drug content

F1 0.1659+0.0030 5.115 102.3

F2 0.1673+0.0007 5.158 103.16

F3 0.3348+0.0003 10.271 102.71

F4 0.3353+0.007 10.286 102.86

F5 0.3387+0.0008 10.390 103.90

F6 0.3386+0.0006 10.387 103.87

* Each value is an average of 3 determinations



5.6.7 In-vitro dissolution study: -

The in-vitro dissolution of all the 6 formulations was carried out using USP

dissolution test apparatus and the results are given in following Tables.

Table 11: Dissolution data of F1. (Conventional tablets of diclofenac sodium)

Time (min)

*Absorbance (nm)

Conc. (µg/ml)

‘C’

Amount of drug released

(mg) (Cx900xD.F/1000)

% Drug released

0 0.0000 0.000 0.000 0.000 15 0.2869+0.0014 8.809 39.641 79.282 30 0.3079+0.0015 9.45 42.525 85.050 45 0.3440+0.0071 10.552 47.484 94.968 60 0.3576+0.0052 10.968 49.356 98.712

* Each value is an average of 3 determinations.

D.F= Dilution Factor (5)

Table 12: Dissolution data of F2. (Conventional tablets of diclofenac calcium)

Time (min)

*Absorbance (nm)

Conc. (µg/ml)

‘C’


(mg) (Cx900xD.F/1000)

% Drug released

0 0.0000 0.000 0.000 0.000 15 0.0454+0.0059 1.437 6.467 12.934 30 0.0577+0.0063 1.813 8.159 16.317 45 0.0743+0.0030 2.319 10.437 20.874 60 0.0963+0.0026 2.991 13.459 26.919 90 0.1148+0.0022 3.556 16.001 32.002 120 0.1347+0.0066 4.194 18.872 37.743 150 0.1581+0.0068 4.878 21.951 43.902 180 0.1829+0.0036 5.635 25.358 50.716 210 0.2126+0.0008 6.541 29.435 58.87 240 0.2495+0.0027 7.668 34.506 69.012 270 0.2950+0.0021 9.057 40.755 81.510 300 0.3465+0.0040 10.324 46.456 92.912 330 0.3625+0.0012 11.17 50.028 100.055





0

10

20

30

40

50

60

70

80

90

100

0 15 30 45 60 90 120 150 180 210 240 270 300 330

Time (min)

Per

cen

tag

e o

f D

rug

Rel

ease

F1

F2

Fig. 7: Comparative dissolution profile of formulations F1 and F2.

Conventional tablet of diclofenac sodium and diclofenac calcium.

The % amount of drug release v/s time (min) was plotted and depicted as

shown in Fig. 7.

Tablets containing diclofenac calcium showed decreased release rate for up to

6 hours compared to diclofenac sodium, which released in one hour. This reduction

in release may be attributed to the poor solubility of calcium salts. Hence calcium

salts of the drug can be exploited for the sustained release dosage forms.



Table 13: Dissolution data of F3. (Diclofenac sodium matrix tablet 1:1)

Time (min)

*Absorbance (nm)

Conc. (µg/ml)

‘C’


(mg) (Cx900xD.F/1000)

% Drug released

0 0.0000 0.000 0.000 0.000

15 0.0415+0.0056 1.318 5.931 5.931

30 0.0458+0.0061 1.449 6.522 6.522

45 0.0498+0.0041 1.571 7.072 7.072

60 0.0584+0.0054 1.834 8.253 8.253

75 0.0632+0.0034 1.981 8.915 8.915

90 0.0805+0.0075 2.509 11.291 11.291

105 0.0990+0.0039 3.073 13.829 13.829

120 0.1353+0.0045 4.182 18.817 18.817

150 0.2383+0.0049 7.326 32.966 32.966

180 0.3378+0.0029 10.368 46.659 46.659

210 0.4464+0.0012 13.68 61.564 61.564

240 0.4991+0.0032 15.29 68.809 68.809

270 0.5526+0.0019 16.922 76.15 76.15

300 0.5875+0.0023 17.987 80.942 80.942

330 0.6328+0.0014 19.369 87.159 87.159

360 0.6734+0.0020 20.608 92.736 92.736

390 0.7241+0.0034 22.156 99.701 99.701

420 0.7295+0.0046 22.321 100.443 100.443





Table 14: Dissolution data of F4. (Diclofenac sodium matrix tablets 1:2)

Time (min)

*Absorbance (nm)

Conc. (µg/ml)

‘C’


(mg) (Cx900xD.F/1000)

% Drug released

0 0.000 0.000 0.000 0.000

15 0.0163+0.0024 0.549 2.471 2.471

30 0.0224+0.0012 0.735 3.308 3.308

45 0.0315+0.0016 1.013 4.558 4.558

60 0.0500+0.0019 1.577 7.096 7.096

75 0.0597+0.0020 1.876 8.445 8.445

90 0.0707+0.0012 2.212 9.957 9.957

105 0.0836+0.0021 2.604 11.72 11.72

120 0.1463+0.0060 4.519 20.337 20.337

150 0.1984+0.0052 6.110 27.497 27.497

180 0.2597+0.0093 7.982 35.921 35.921

210 0.3058+0.0016 9.388 42.248 42.248

240 0.3493+0.0083 10.715 48.218 48.218

270 0.4032+0.0060 12.360 55.623 55.623

300 0.4585+0.0049 14.048 63.219 63.219

330 0.5450+0.0061 16.691 75.112 75.112

360 0.5918+0.0097 18.118 81.533 81.533

390 0.6270+0.0138 19.191 86.359 86.359

420 0.6579+0.0106 20.136 90.616 90.616

450 0.6845+0.0022 20.948 94.267 94.267

480 0.7109+0.0035 21.753 97.889 97.889





Table 15: Dissolution data of F5. (Diclofenac calcium matrix tablets 1:1)

Time (min)

*Absorbance (nm)

Conc. (µg/ml)

‘C’


(mg) (Cx900xD.F/1000)

% Drug released

0 0.000 0.000 0.000 0.0000

15 0.0511+0.0012 1.611 7.25 7.25

30 0.1102+0.0034 3.415 15.369 15.369

45 0.2412+0.0032 7.414 33.364 33.364

60 0.3361+0.0072 10.311 46.401 46.401

75 0.4262+0.0016 13.063 58.787 58.787

90 0.4892+0.003 14.987 67.444 67.444

105 0.5373+0.0021 16.455 74.051 74.051

120 0.5878+0.0025 17.998 80.994 80.994

135 0.6254+0.0047 19.143 86.143 86.143

150 0.6394+0.0067 19.570 88.065 88.065

165 0.6667+0.0066 20.405 91.824 91.824

180 0.6844+0.0050 20.945 94.256 94.256

195 0.7055+0.0038 21.589 97.154 97.154

210 0.7210+0.0022 22.061 99.275 99.275





Table 16: Dissolution data of F6. (Diclofenac calcium matrix tablets 1:2)

Time (min)

*Absorbance (nm)

Conc. (µg/ml)

‘C’


(mg) (Cx900xD.F/1000)

% Drug released

0 0.000 0.000 0.000 0.000

15 0.0312+0.0025 1.004 4.516 4.516

30 0.0998+0.0021 3.098 13.94 13.94

45 0.1404+0.0035 4.337 19.517 19.517

60 0.2183+0.0036 6.715 30.221 30.221

75 0.2841+0.0043 8.725 39.263 39.263

90 0.3489+0.0031 10.704 48.171 48.171

105 0.4334+0.0012 13.283 59.775 59.775

120 0.5021+0.0022 15.379 69.205 69.205

135 0.5782+0.0049 17.702 79.65 79.65

150 0.6174+0.0041 18.899 85.049 85.049

165 0.6469+0.0050 19.799 89.099 89.099

180 0.6708+0.0088 20.529 92.382 92.382

195 0.6846+0.0018 20.950 94.278 94.278

210 0.7001+0.0071 21.423 96.404 96.404



0

20

40

60

80

100

120

0 15 30 45 60 75 90 105 120 150 180 210 240 270 300 330 360 390 420

Time (min)

Per

cen

tag

e o

f D

rug

Rel

ease

F3

F5

Fig. 8:Comparative dissolution profile of formulations F3 and F5



0

20

40

60

80

100

120

0 30 60 90 120 180 240 300 360 420 480

Time (min)

Per

cent

age

of D

rug

Rel

ease

F 4

F6

Fig. 9: Comparative dissolution profile of formulations F4 and F6

Comparison of Diclofenac sodium release with Diclofenac calcium from matrix

tablets (Fig. 8 and 9).

As mentioned before, the release of diclofenac sodium from the conventional

tablet is better due to the solubility reason. It is a better soluble salt compared to other

salt forms. However, the release from the matrix tablets reduced drastically. There

may be complex mechanism involved in contrary to simple swelling, diffusion and

erosion concept. There was initial very slow release of drug for the first few minutes

approximately 105 minutes. This may be due to the inability of the tablet to reswell

quickly. However, once the tablet swelling was complete there was better release of

drug (after 120 minutes), resembles more or less similar to that of diclofenac calcium

from matrix tablet.

The initial delay in release from F3 may be due to the complex formation

between drug and polymer. Calcium is a divalent ion. Hence, there may be formation

of complex between diclofenac, calcium ions and alginate. This leads to very slow



release of the drug initially. However, when the complex breaks, the release rate may

suddenly increase for few minutes, followed by further reduction due to solubility of

diclofenac calcium, which is also present in the matrix.

F3 formulation released 100% of drug in 7hours, compared to F5 formulation,

which in turn released 99% of drug in just 4 hours. Based on solubility parameter and

in comparison to the conventional tablet dissolution profile, F5 was supposed to be

released in much slower rate compared to F3. But it released at a faster rate from the

matrix. Theoretically speaking, the release of drug from alginate matrix takes place

due to the combination of swelling, erosion and diffusion. However, this mechanism

is applicable as long as there is no interaction between drug and alginate. All the

formulations may have followed this mechanism except the formulation F3 as well as

F4. There may be some interaction between the drug and other ingredients responsible

for the formation of matrix by gelation method, as mentioned before.

The proposed mechanism for the delayed release of diclofenac sodium from

the matrix tablets is as follows:

Diclofenac sodium salt when dispersed in sodium alginate solution, some

amount may go into the solution. When calcium chloride is added to the dispersion to

form gelation, the dissolved part of the diclofenac sodium may get converted to the

diclofenac calcium along with the simultaneous formation of calcium alginate. IR

spectral studies revealed that there is a mixture of both the salts of diclofenac are

present in the diclofenac sodium matrix as peaks for both diclofenac sodium and

diclofenac calcium are present (as shown in fig. 15-19) It was observed that, there is a

significant difference in the physical appearance, between matrix formation of

diclofenac calcium in sodium alginate and diclofenac sodium in sodium alginate.

When calcium chloride solution was added to the sodium alginate solution containing



diclofenac sodium, a very white colored matrix was formed and this is may be due to

the milky precipitation of diclofenac calcium, with simultaneous formation of calcium

alginate. However, this physical appearance was not observed when calcium

diclofenac dispersed in sodium alginate. This suggests that, when calcium chloride

added to the sodium alginate solution containing sodium salt of drug and caused

gelation, may lead to some sort of complexation between drug and polymer, which in

turn may releases, the drug slowly. The complexation formation can be ruled out

when calcium salts are placed in alginate and no gelation occurs. This indicates that

the calcium ion is having greater affinity to the drug than alginate.

This mechanism may not exist in the formulation F5, where simple swelling,

diffusion, erosion or disintegration with dissolution mechanism may exist. As a result,

drug releases at a faster rate.

Hence, the release of sodium salts of the drug from alginate can be expected more

slower than calcium salts, though calcium salts are less soluble.

0

20

40

60

80

100

120

0 15 30 45 60 90 120 150 180 210 240 270 300 330

Time (min)

Per

cen

tag

e o

f Dru

g R

elea

se

F2F5

Fig. 10: Comparative dissolution profile of formulations F2 and F5

.



Comparison of diclofenac calcium release from the conventional and matrix

tablets (Fig. 10)

In contrast to the nature of drug release of diclofenac sodium from both

conventional and matrix tablets, diclofenac calcium was released better from matrix

tablets (Table 12 and 15). The release rate of diclofenac calcium from matrix was

initially slow (for 15 minutes) followed by rapid release for next one hour. However,

the release of diclofenac calcium from conventional tablet was better initially (for 15

minutes) compared to the matrix tablet, followed by very slow release of the drug.

In 330 minutes, 100% of drug was released from conventional tablet, where

as matrix tablets released the same amount in 210 minutes.

The initial slow release of the drug from the matrix tablet is attributed to the

reswelling property of alginate and diffusion of the drug. However, the sudden

increment in release after 15 minutes is due to the reason that the tablet disintegrates

faster and the release is attributed to the solubility of the drug. The reswelling nature

of alginate helps in disintegration. However, the conventional tablet disintegrated at a

much slower rate. As a result, the release was delayed until complete disintegration of

the tablet. Once the tablet disintegrated the release profile observed remained more or

less similar to that obtained with conventional tablets. Hence, calcium diclofenac salts

can be used for controlled release formulations.



Table 17: Dissolution data of Voveran-50 (conventional tablet)

Time (min)

*Absorbance (nm)

Conc. (µg/ml)

‘C’


(mg) (Cx900xD.F/1000)

% Drug released

0 0.000 0.000 0.000 0.000

15 0.1742+0.0024 5.369 24.161 48.322

30 0.2890+0.0052 8.874 39.931 79.862

45 0.3225+0.0042 9.896 44.533 89.066

60 0.3654+0.0069 11.206 50.426 100.852



Table 18: Dissolution data of Nac-50 (conventional tablet)

Time (min)

*Absorbance (nm)

Conc. (µg/ml)

‘C’


(mg) (Cx900xD.F/1000)

% Drug released

0 0.000 0.000 0.000 0.000

15 0.2968+0.0054 9.112 41.004 82.008

30 0.3315+0.0057 10.171 45.769 91.538

45 0.3485+0.0072 10.69 48.104 96.209

60 0.3589+0.0089 11.007 49.533 99.006


D.F= Dilution Factor, SD= Standard Deviation



Table 19: Dissolution data of Voveran SR-100.

Time (min)

*Absorbance (nm)

Conc. (µg/ml)

‘C’


(mg) (Cx900xD.F/1000)

% Drug released

0 0.000 0.000 0.000 0.000

15 0.1168+0.0009 3.617 16.275 16.275

30 0.1392+0.0015 4.301 19.355 19.355

60 0.1974+0.0025 6.077 27.348 27.348

90 0.2014+0.0022 6.199 27.897 27.897

120 0.2341+0.0031 7.198 32.389 32.389

150 0.2846+0.0051 8.739 39.326 39.326

180 0.3351+0.0041 10.281 46.264 46.264

210 0.4083+0.0032 12.515 56.319 56.319

240 0.4469+0.0029 13.694 61.622 61.622

270 0.4734+0.0025 14.503 65.262 65.262

300 0.5058+0.0015 15.492 69.713 69.713

330 0.5306+0.0008 16.249 73.12 73.120

360 0.5568+0.0016 17.049 76.719 76.719

390 0.5892+0.0012 18.038 81.17 81.170

420 0.6198+0.0022 18.972 85.373 85.373

450 0.6428+0.0021 19.674 88.533 88.533

480 0.6799+0.0016 21.267 95.703 95.703





Table 20: Dissolution data of Divon SR-100

Time (min)

*Absorbance (nm)

Conc. (µg/ml)

‘C’


(mg) (Cx900xD.F/1000)

% Drug released

0 0.000 0.000 0.000 0.000

15 0.0981+0.0020 3.046 13.707 13.707

30 0.1240+0.0025 3.837 17.264 17.264

60 0.1392+0.0022 4.301 19.353 19.353

90 0.1798+0.0024 5.540 24.93 24.930

120 0.2019+0.0041 6.215 27.966 27.966

150 0.2400+0.0052 7.378 33.2 33.200

180 0.2890+0.0031 8.874 39.931 39.931

210 0.3250+0.0062 9.972 44.876 44.876

240 0.3810+0.0019 11.682 52.569 52.569

270 0.4416+0.0015 13.532 60.894 60.894

300 0.4718+0.0009 14.454 65.042 65.042

330 0.5069+0.0072 14.525 69.864 69.864

360 0.5375+0.0059 16.459 74.068 74.068

390 0.5689+0.0045 17.418 78.381 78.381

420 0.6092+0.0037 18.648 83.917 83.917

450 0.6348+0.0032 19.430 87.434 87.434

480 0.6768+0.0023 20.712 93.203 93.203





0

20

40

60

80

100

120

0 30 60 90 120 150 180

Time (min)

Per

cen

tag

e o

f Dru

g R

elea

se

F1F2

Voveran-50Nac-50

Fig. 11: Comparative Dissolution profile of Marketed conventional tablets and

formulations F1 and F2

0

20

40

60

80

100

120

0 30 90 150 210 270 330 390 450

Time (min)

Per

cen

tag

e o

f Dru

g R

elea

se

F4F2Voveran SR - 100Divon SR - 100

Fig. 12: Comparative Dissolution profile of Marketed sustained release tablets

and formulations F2and F4



Comparison with Marketed products.

The evaluation parameters tested and compared was in-vitro dissolution

profile. The values obtained for in-vitro dissolution data are given in Table17 to 20

and the dissolution profiles are given in Fig. 11 and 12.

The conventional marketed tablets of diclofenac sodium gave 100% drug

release in 1 hour of dissolution study. Formulation F1 showed similar release profile

compared to marketed tablet, F2 showed slower release rate compared to marketed

formulation, indicating calcium salts are suitable for sustaining the drug release.

The sustained release marketed tablets such as Voveran-SR-100 gave 95% of

drug release in 8 hour while Divon-SR-100 gave 93% of drug release in 8 hours of

dissolution study. Formulation F4 showed similar release profile as marketed tablets

i.e. 98% of drug release in 8 hours of dissolution study.

Comparison of ratios:

As the concentration of polymer increases, the release rate was found to be

decreased as shown in figure 13 and 14. In general more amount of polymer reduces

the entrapment efficiency and also the diffusion length may increase. This may result

in delayed release of the drug.



0

20

40

60

80

100

120

0 30 60 90 120 180 240 300 360 420 480

Time (min)

Per

cen

tag

e o

f D

rug

Rel

ease

F3

F4

Fig. 13: Comparative dissolution profile of Formulations F3 and F4.

0

20

40

60

80

100

120

0 15 30 45 60 75 90 105 120 135 150 165 180 195 210

Time (min)

Per

cen

tag

e o

f Dru

g R

elea

se

F5

F6

Fig. 14: Comparative dissolution profile of Formulations F5 and F6.



5.7 Curve Fitting Analysis:

The release data of diclofenac were fitted to models representing zero order

and first order kinetics. The data were processed for regression analysis using MS

EXCEL statistical function. The corresponding regression co-efficient values are

shown in Table 21.

Table 21: Comparison of Regression co-efficient values for different

formulations.

Regression co-efficient values

“R2 values” Formulation

Zero Order First order

F3 0.9707 0.9010

F4 0.9906 0.8686

F5 0.9041 0.7028

F6 0.9662 0.7974

The pattern of drug release (Fig: and) and the regression co-efficient values

(Table 20), both indicate the zero order release kinetics from the matrix tablets. (R2

value was above 0.95 for all the formulation on an average).

Release of drug from matrix tablets containing hydrophilic polymers involves

factors of diffusion. As a gradient varies, the drug is released, and the distance for the

diffusion increases, which is referred as Higuchi’s kinetics. The in-vitro release

profiles of drug from all the formulations could be best expressed by Higuchi’s

equation and regression co-efficient values were found out and given in table 22.

Table 22: Regression co-efficient values of different formulations for the Higuchi

plot.

Formulation Co-efficient of Correlation values “R2 values”

F3 0.9365 F4 0.9538 F5 0.9702 F6 0.9798



The Higuchi plot, square root of time and % amount drug release for all the

formulations are shown in Fig. 20 – 23.

The figures indicate a linear relationship throughout the study as the R2 values

range from 0.9365 to 0.9798. The appearance of straight line indicated that the release

was diffusion rate limited. Initial variation in linearity for F3 and F4 (Fig 20 and 21)

is due to the complex mechanism involved for the sodium salt of drug in matrix.

However the same mechanism can be for F5 and F6 (Fig 22 and 23).

0

20

40

60

80

100

120

0 5 10 15 20 25

Square root of time (min)

Per

cen

tag

e o

f D

rug

Rel

ease

F3

Fig. 20: Higuchi plot of formulation F3



0

20

40

60

80

100

120

0 5 10 15 20 25


Per

cen

tag

e o

f D

rug

Rel

ease

F4


0

20

40

60

80

100

120

0 5 10 15 20


Per

cen

tag

e o

f Dru

g R

elea

se

F5




0

20

40

60

80

100

120

0 5 10 15 20


Per

cen

tag

e o

f Dru

g R

elea

se

F6


5.8 Stability study:

The results of the stability study of the tablets at room temperature (27°C), at

45°C and at 60°C are shown in Table23 and 24.

Table 23: % Drug Content of formulations F3 and F4 under different conditions.

Percentage Drug Content

F3 F4 Time in weeks

* RT 45°C 60°C * RT 45°C 60°C

0 102.95 102.97 102.89 102.86 103.41 103.04

2 102.89 102.92 102.86 102.84 103.40 103.06

4 102.80 102.85 102.79 102.99 103.35 102.98

6 102.72 102.73 102.72 102.73 103.32 102.94

8 102.69 102.68 102.61 102.63 103.52 103.15

* RT Room Temperature



Table 24: % Drug Content of formulations F5 and F6 under different conditions.

Percentage Drug Content

F5 F6 Time in weeks

* RT 45°C 60°C * RT 45°C 60°C

0 103. 80 104.12 103.65 104.45 104.12 103.87

2 103.82 104.14 103.62 104.42 104.16 103.80

4 103.75 104.16 103.67 104.32 103.89 103.72

6 103.65 103.95 103.61 104.40 103.91 103.76

8 103.66 103.97 103.45 104.38 103.85 103.69

* RT Room Temperature

The results of stability studies indicate that all the formulations are found to be

stable when stored under different conditions.

C.h. 5 R

esults and Discussion

Dept of P

harmaceutics, N

.G.S.M

.I.P.S, M

angalore 55

Fig 15: IR Spectra of Sodiumalginate

C.h. 5 R


Dept of P

harmaceutics, N

.G.S.M

.I.P.S, M

angalore 56

Fig 16: IR spectra of Diclofenac sodium

C.h. 5 R


Dept of P

harmaceutics, N

.G.S.M

.I.P.S, M

angalore 57

Fig 17: IR spectra of Diclofenac sodium matrix

C.h. 5 R


Dept of P

harmaceutics, N

.G.S.M

.I.P.S, M

angalore 58

Fig 18: IR spectra of Diclofenac calcium

C.h. 5 R


Dept of P

harmaceutics, N

.G.S.M

.I.P.S, M

angalore 59

Fig 19:IR spectra of the Diclofenac calcium matrix

Ch. 6 Summary


SUMMARY The goal in the development of controlled drug delivery systems is to develop

systems that are safe, reproducible and effective. Matrix tablets are controlled release

matrix drug delivery systems containing drug through out the structure and governs

the release rate of the entrapped active substance.

Diclofenac is an non-steroidal anti- inflammatory drug (NSAID), used for

rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, acute musculoskeletal

injury and dysmenorrhea. Due to its short half- life, the frequency of administration is

more and importantly it produces frequent side effects are gastrointestinal

disturbances, peptic ulceration and gastrointestinal bleeding. Hence in this study an

attempt has been made to formulate a calcium salt of diclofenac and formulate into

conventional and matrix tablets and compare its release with the diclofenac sodium

salt conventional tablets and matrix tablets.

Calcium salts of diclofenac was prepared by adding a 7.5mmoles of calcium

chloride solution drop by drop till precipitation is complete into 1% diclofenac

sodium solution and the precipitate formed was washed and dried.

Alginate matrix tablets of diclofenac sodium and diclofenac calcium were

prepared by ionic gelation method. The ionic gelation process involves the stacking of

glucuronic acid blocks of alginate chains with the formation of egg box junction,

which acts as a barrier for drug release. The matrices of diclofenac sodium and

diclofenac calcium were prepared in 1:1 and 1:2 drug: polymer ratios.

The percentage yield of matrix was found to be in the range of 78.5% to

89.5%. The yield was found to be the highest in the case of lowest drug to polymer

ratio. The drug content in the calcium alginate matrix was found to be highest in case

of diclofenac cal matrix than compared to diclofenac sodium matrix. This may be

Ch. 6 Summary


probably due to the more solubility of diclofenac sodium compared to diclofenac

calcium, that may be lost during the washing stage.

UV scanning of the prepared matrix containing the drug shows the peak at

276nm, which confirms the presence of diclofenac in matrix.

The tablets were prepared by direct compression. The drug release from the

diclofenac calcium conventional tablets was found to be slowest compared to

diclofenac sodium conventional tablets. This may be attributed to the less solubility of

calcium salts compared to sodium salts.

The drug release from the matrix tablets was found to be zero order, with the

slowest release up to 8 hours obtained from diclofenac sodium matrix tablets with the

drug to polymer ratio of 1:2. The drug release from diclofenac calcium matrix tablets

was found to be higher compared to diclofenac sodium matrix tablets.

When calcium chloride solution was added to the sodium alginate solution

containing diclofenac sodium, a very white colored matrix was formed and this may

be due to the milky precipitation of diclofenac calcium from diclofenac sodium, with

simultaneous formation of calcium alginate. However, this physical appearance was

not observed when diclofenac calcium dispersed in sodium alginate. This may lead to

some sort of complexation between drug and polymer, which in turn may releases,

drug slowly. IR spectral studies revealed the presence of diclofenac sodium and

diclofenac calcium in the matrix of diclofenac sodium matrix. Therefore the drug

release from the diclofenac sodium is reduced drastically.

The Higuchi plot was linear for majority of the drug release, indicating the

release was diffusion rate limited. Initial variation in linearity is due to the complex

formation in formulations F3 and F4. Hence, the drug release is diffusion rate limited.

Stability study indicated that all the formulations were found to be stable when

stored at different temperatures.

Ch. 7 Conclusion


CONCLUSION

The following conclusions are drawn from the results and discussion described in

previous chapter.

Ø Diclofenac calcium salt was prepared by precipitation method and formation

of calcium salt of drug was confirmed by calcium oxalate and flame test.

Ø Conventional tablets were prepared by direct compression method. The

prepared tablets showed relatively good hardness and drug content was within

pharmacopoeial limits. In vitro release study show slow release for diclofenac

calcium compared to diclofenac sodium, since calcium salts are less soluble

than sodium salts.

Ø Matrix of drugs were prepared by ionic gelation method and based on the

amount of drug loaded in matrix, the entrapment efficiency was calculated.

Entrapment efficiency of diclofenac calcium was greater than diclofenac

sodium, since the solubility of diclofenac sodium is more; it got loss more and

lost during washing stage.

Ø Matrix tablets were prepared by direct compression, showed good hardness

and friability. In-vitro release showed slow release of drug in case of

diclofenac sodium in matrix compared to diclofenac calcium in matrix. IR

spectral study revealed the presence of both salts in diclofenac sodium matrix.

This may be reason for the slow release of the drug. Initial difference in

release is due to swelling takes place immediately in case of diclofenac

calcium matrix compared to sodium matrix

Ø The release of drug from matrix tablets takes place by swelling, diffusion and

erosion mechanism along with the some complex mechanism in diclofenac

sodium matrix.

Ch. 7 Conclusion


Ø The order of drug release was found to be zero order for all the matrix tablets.

Drug release data was better suitable to Higuchi’s diffusion model and the

release of drug was diffusion rate limited from all the matrix tablets.

From, the above findings, it is concluded that calcium diclofenac can be used

for sustained release formulation, provided if further in-vivo studies should be carried

out. Further the release of diclofenac sodium from alginate matrix indicated that, an

ideal approach for sustained release dosage form. Alginate not only avoids the drug

release in stomach, also proved as a mucoprotective agent. Hence it avoids the

irritation to the mucus layer of intestine. The complex formation and subsequent slow

release of sodium salt of drug is an advantage of using alginate as an matrix forming

material.

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diclo invitro

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