tablets - national university

Technology of Solid Dosage Forms &Disperse Systems

Dr. Mekaiel Amiel Mekaiel M.Sc. Pharmaceutical Technology

National University

Tablets

Outline

1. Introduction & definition

2. Tablets Advantages and disadvantages

3. Types of tablets

4. Tablet ingredients

5. Tablet manufacturing

6. Tablet testing or tablet qualifications QC

7. Tablet press

8. Tablet coating

Learning outcomes

By the end of this session student should be able to:

1. Explain the detailed formulation and manufacturing unit operation involved in the manufacture of Tablets.

2. Identify the excipients used and their role/function in the formula.

3. Describe different techniques employed in production of tablets.

4. Differentiate and compare between different types of tablets.

INTRODUCTION

• The oral route is the most common way of

administrating drugs, and among the oral dosage

forms tablets of various different types are the most

common type of solid dosage forms in contemporary

use.

INTRODUCTION

• The idea of forming a solid dosage form by powder

compression is not new. In 1843 the first patent for a

hand operated device used to form a tablet was

granted.

• Definition:

Tablets may be defined as solid pharmaceuticals

dosage forms containing drug substances with or

without suitable diluents and have been

traditionally prepared by either compression or

molding methods.

INTRODUCTION

INTRODUCTION

• Recently punching of laminated sheets,

electronic deposition methods and three

dimensional printing methods have been used

to make tablets.

INTRODUCTION

• Tablets are used mainly for systemic drug

delivery but also for local drug action.

• The term compressed tablets is believed to

have been used by John Wyeth and brother of

Philadelphia.

Tablets Advantages

• Tablets are popular for several reasons:

1. The oral route represents a convenient and safe

way of drug administration.

2. Physically and chemically stable.

3. The preparation procedure enables accurate

dosing.

4. Easy to handle and can be prepared using several

approaches.

5. Can be mass produced, with robust quality

controlled production procedures, resulting in

product with good quality and affordable price.

Tablets Disadvantages

• The bioavailability of poorly water soluble

drugs or poorly absorbable drugs.

• Some drug may cause irritant effects and harm

the GI mucosa.

Types of tablets

• Most commercial tablets can be divided into

two general classes:

I. Compressed tablets.

II. Molded tablets.

i. Compressed tablets

• These tablets are formed by compression

and in their simplest form, contain no

special coating. They are made from

powdered, crystalline, or granular

materials, alone or in combination with

excipients.

i. Compressed tablets

• Types :

1. Sugar coated tablets (SCT):

• Theses are compressed tablets surrounded by

a sugar coating.

• Such coating is used to mask objectionable

tastes or odor and in protecting materials

sensitive to oxidation.

1. Sugar coated tablets (SCT):

• These coating were once quite common, and

generally lost commercial appeal due to the

high cost of process validation.

• Recently they have made a comeback due to

patient popularity and technical advances.

2. Film coated tablets (FCT):

• These are compressed tablets that are covered

with a thin layer or film of a water soluble

material.

• Film coating imparts the same general

characteristics as sugar coating, with the

added advantage of a greatly reduced time

period required for the coating operation.

• First choice of formulators.

3. Enteric coated tablets (ECT):

• These are compressed tablets coated with

substances that resist solution in gastric fluid

but disintegrate in the intestine.

• Enteric coating can be used for tablets

containing drug substances that are

inactivated or destroyed in the stomach, for

those that irritate the mucosa or as means of

delayed release of medication.

4. Multiple compressed tablets (MCT):

• These are compressed tablets made by more

than one compression cycle.

• This process is best used when separation of

active ingredients is needed for stability

purpose, or if the mixing process is inadequate

to guarantee uniform distribution of two or

more active ingredients.

• Layered tablets: - Such tablets are

prepared by compressing additional tablets

granulation on a previously compressed

granulation.

• The operation may be repeated to produce

multilayered tablets of two or three or

more layers.

• Special tablet press are required to make

layered tablets.

4. MULTIPLE COMPRESSED TABLETS (MCT):

4. Multiple compressed tablets (MCT):

• Press-coated tablets:- Such tablets also

referred as dry-coated, are prepared by feeding

previously compressed tablets into special

tableting machine and compressing another

granulation layer around the performed tablets.

• They have all the advantages of compressed

tablets.

4. Multiple compressed tablets

(MCT):

Press-coated tablets

• Masking the taste of drug substance in the core

tablets.

• Press coated tablets also can be used to incompatible

drug substances.

5. Controlled Release Tablets (CRT):

• Compressed tablets can be formulated to

release the drug slowly over a prolonged

period of time.

• Hence these dosage forms have been referred

to as prolonged release or sustained release

dosage forms as well.

5. Controlled Release Tablets (CRT):

• These tablets (as well as capsule version) can be

categorized into three types:

I. Those that respond to some physiological condition

to release the drug such as enteric coating.

II. Those that release the drug in a relatively steady,

controlled manner, and

III. Those that combined combination of mechanisms

to release pulses of drug such as repeat- action

tablets

5. CONTROLLED RELEASE TABLETS (CRT):

• Other names of these tablets can be :-

Extended release, Sustained release, Prolonged

release, Delayed release, and in the case of the

pulsatile tablets :- Repeat action, Pulsatile

release or pulse release.

6. Tablets for Solution (CTS):

• Compressed tablets to be used for preparation

of solutions or imparting given characteristics

to solutions must be labeled to indicate that

they are not to be swallowed.

7. Effervescent Tablets:

• In addition to the drug substance, these

contain sodium bicarbonate and an organic

acid such as tartaric or citric.

• In the presence of water these additives react,

liberating carbon dioxide that acts as

disintegrator and produces effervescence.

• Effervescent tablets are soluble.

8. Compressed Tablets or Inserts:

• Occasionally, vaginal tablets, such as

Metronidazole tablets, are prepared by

compression.

• In this case as well as for any tablet intended

for administration other than by swallowing,

the label must indicate the manner in which it

is to be used.

9. Buccal and Sublingual tablets:

• These are small, flat and oval tablets.

• Tablets intended for buccal (the space between the lip

and gum in the mouth) administration by inserting into

the buccal pouch may dissolve or erode slowly;

therefore, they are formulated, and compressed with

sufficient pressure to give a hard tablet.

9. Buccal and Sublingual tablets:

• Some newer approaches have employed

materials that act as bioadhesives to increase

absorption of the drug.

10.Chewable tablets

• Chewable tablets are chewed and thus

mechanically disintegrated in the mouth.

• They are used primarily to accomplish a quick

and complete disintegration of the tablet and

hence obtain a rapid drug effect, or to

facilitate the intake of the tablet. A common

example of the former is antacid tablets.

10.Chewable tablets

• Another advantage of a chewable tablet is that

this type of medication can be taken when

water is not available.

• Chewable tablets are similar in composition to

conventional tablets except that a disintegrant

is normally not included in the composition.

• Flavoring and coloring agent are common,

sorbitol and mannitol are common examples of

filler.

II. Molded tablets

or tablets triturates (tt) • Tablet triturates usually are made from moist

material, using a triturate mold that gives them

the shape of cut section of a cylinder.

• Such tablets must be completely and rapidly

soluble.

• The problem arising from compression of

these tablets is the failure to find a lubricant

that is completely water soluble.

II. Molded tablets

or tablets triturates (tt)

1. Dispensing tablets (DT):

• These tablets provide a convenient quantity of

potent drug that can be incorporated readily

into powders and liquids, thus circumventing

the necessity to weigh small quantities.

• These tablets are supplied primarily as a

convenience for extemporaneous

compounding and should never be dispensed

as a dosage form.

2. Hypodermic tablets (HT):

• Hypodermic tablets are soft, readily soluble tablets

and originally were used for the preparation of

solution to be injected.

Tablet ingredients

• In addition to the active or the therapeutic

ingredient, tablets contain a number of inert

materials.

• The latter are known as additives or excipients.

• They can be classified to the part they play in

the finished tablets.

Tablet ingredients

• The first group contains that help to impart

satisfactory processing and compression

characteristics to the formulation.

• These include diluents, binders, glidants and

lubricants.

Tablet ingredients

• The second group of added substances helps to

give additional desirable physical

characteristics to the finish tablets. Included in

this group disintegrants, surfactants, colors and

in the case of chewable tablets flavors and

sweetening agents and in the case of controlled

release tablets, polymers or hydrophobic

materials.

Tablet ingredients

• In some cases, antioxidants or other materials

can be added to improve stability and shelf-

life.

• Although the term inert has been applied to

these added materials, it has become apparent

that there is an important relationship between

the properties of the excepients and the dosage

form containing them.

Tablet ingredients

• Preformulation studies demonstrate their

influence on stability, bioavailability and the

process by which the dosage forms are

prepared.

1. Diluents

• Frequently, the single dose of the active

ingredient is small, and an inert substance is

added to increase the bulk to make the tablet a

practical size for compression, these inert

materials are called diluents.

1. Diluents

• Diluents used for this purpose include:

diclacium phosphate, calcium sulphate,

lactose, cellulose, kaolin, mannitol, sodium

chloride, dry starch and powdered sugar.

• Most formulators of immediate release tablets

tend to use consistently only one or two

diluents selected from the above group in their

tablet formulations.

1. Diluents

• Usually these have been selected on the basis

of experience and cost factors.

• However, the compatibility of the diluents

with the drug must be considered.

2. Binders

• Agents used to impart cohesive qualities to the

powdered material are referred to as binders or

granulators.

• They impart a cohesiveness to the tablet

formulation that ensure the tablet remaining

intact after compression, as well as improving

the free- flowing qualities by the formulation

of granules of desired hardness and size.

2. Binders

• Materials commonly used as binders include:

starch, gelatin and sugars such as sucrose,

glucose, dextrose, molasses and lactose.

• Natural and synthetic gums that have been used

include acacia, sodium alginate, extract of Irish

moss, panwar gum, ghatti gum, mucilage of

Isapol husks, carboxymethyl cellulose, methyl

cellulose, polyvinyl pyrrolidone, veegum and

Iarch arabogalacton.

2. Binders

• Other agents that may be considered binders under

certain circumstances are polyethylene glycol, ethyl

cellulose, waxes, water and alcohol.

• The quality of binder used has considerable influence

on the characteristics of the compressed tablets. The

use of too much binder or too strong binder will make

a hard tablet that will not disintegrate easily and will

cause excessive wear of punches and dies.

2. Binders

• Binders can be used in different forms (dry or

solution form). Examples for different forms

of binders: starch paste, gelatin solution and

cellulosic solution.

3. Lubricants

• Lubricants have a number of functions in tablet

manufacture.

1. They prevent adhesion of the tablet material to the

surface of the dies and punches,

2. reduce interparticle friction,

3. facilitate the ejection of tablets from the die cavity,

and may

4. improve the rate of flow of the tablet granulation.

3. Lubricants

• Commonly used lubricants include talc,

magnesium stearate, calcium stearate, steric

acid, glycerol behanate, hydrogenated

vegetable oil and polyethylene glycol.

• Most lubricants with exception of talc, are

used in concentrations below 1% when used

alone, talc may require concentrations as high

as 5%.

3. Lubricants

• Lubricants are in most cases hydrophobic

materials.

• Poor selection or excessive amounts can result

in water proofing the tablets, resulting in poor

tablet disintegration and/or delayed dissolution

of the drug substance.

3. Lubricants

• The method of adding a lubricant to a

granulation is important if the material is to

perform its function satisfactory.

• After adding the lubricant, the granulation is

tumbled or mixed gently to distribute the

lubricant without coating the particle too well

or breaking them to finer particles.

4. Glidants

• A glidant is a substance that improves the flow

characteristics of the powder mixture.

• These materials always are added in the dry

state just prior to compression (i.e. during the

lubrication step).

4. Glidants

• Colloidal silicon dioxide is the most

commonly used glidant and generally is used

in low concentrations of 1% or less.

• Talc is also used and may serve the dual

purpose of lubricant/glidant.

4. Glidants

• It is especially important to optimize the order

of addition and the mixing process for these

materials, so maximize their effect and to

make sure that their influence on the

lubricant(s) is minimized.

5. Disintegrants

• A disintegrant is a substance or a mixture of

substances, added to a tablet to facilitate its

breakup or disintegration after administration.

• The active ingredients must be released from

the tablet matrix as efficiently as possible to

allow rapid dissolution.

5. Disintegrants

• Material serving as disintegrants have been

classified chemically as starches, clays,

celluloses, aligns, gums and cross-linked

polymers. Starches 5% concentration is

suggested, but if more rapid disintegration is

desired this amount may be increased to 10%

or 15%.

5. Disintegrants

• A group of materials known as super-

disintegrants have gained in popularity as

disintegrating agents.

• The name comes from the low levels (2-4%) at

which they are completely effective.

Crosscarmellose, crosspovidone and sodium

starch glycollate represent example of a cross-

linked cellulose, a cross- linked polymer and a

cross- linked starch, respectively.

5. Disintegrants

• The disintegrating agent usually is mixed with

the active ingredients and diluents prior to

granulation.

• In some case it may be advantageous to divide

the starch into two portions: one portion is

added to the powder formula prior to

granulation, and the remaining is mixed with

the lubricant and added prior to compression.

5. Disintegrants

• Incorporated in this manner, the starch serves a

double purpose; the portion added to the

lubricant rapidly breaks down the tablet to

granules, and the starch mixed with the active

ingredients disintegrates the granules into

smaller particles.

6. Coloring agents

• Colors in compressed tablets serve function

other than making the dosage form more

esthetic in appearance.

• Color helps the manufacturer to control the

product during preparation, as well as serving

as a mean of identification to the users.

6. Coloring agents

• All colorants used in the pharmaceuticals must

be approved and certified by the FDA.

• For several decades colorants have been a

subjected to rigid toxicity standards, and as a

result a number of colorants have been

removed from an approval list of Food, Drug

and Cosmetic Act (FD&C) colors, or delisted.

6. Coloring agents

• The most common method of adding color to a

tablet formulation is to dissolve the dye in the

binding solution prior to the granulation

process.

• Another approach is to adsorb the dye on

starch or calcium sulphate from its aqueous

solution; the resultant powder is dried and

blended with the other ingredients.

6. Coloring agents

• A problem may occur during drying is migration of

dyes which can be reduced by slow drying at low

temperature and stirring the granulation while it is

drying.

• Other additives have been shown to acts as dye-

migration inhibitors. Tragacanth (1%), acacia (3%),

attapulgite (5%) and talc (7%) were effective in

inhibiting the migration of FD&C Blue No. 1 in

lactose.

7. Flavoring agents

• In addition to sweetness that may be afforded

by the diluents of the chewable tablets e.g.

mannitol or lactose, artificial sweetening agent

may be included.

• Sweeteners other than sugar have the

advantage of reducing the bulk volume,

considering the quantity of sucrose required to

produce the same degree of sweetness.

7. Flavoring agents

• Being present in small quantities, they do not

affect markedly the physical characteristics of

the tablet granulation.

Reference

• Remington: The Science and Practice

of Pharmacy

• Aulton’s Pharmaceutics – The Science

of Dosage Form Design

Tablet manufacturing


• The pharmaceutical industry is highly regulated and

must comply with current good manufacturing

practices (cGMPs).

• In terms of equipment, this translates into preparing

products in totally enclosed systems by processes that

minimize the handling and transfer of materials.


• There are three general methods typically used for

commercial tablet preparation: the wet granulation

method, the dry granulation method (slugging) and

the direct compression.

• Irrespective to the previously mentioned production

routes the first stage is likely to involve the intimate

mixing together of several powdered ingredient.

Powder mixing

• The successful mixing of fine powder together is

believed to be one of the more difficult unit

operations, because, unlike the situation of liquid,

perfect homogeneity is practically unattainable.

• All that is possible to realize a maximum degree of

randomness in the arrangement of the individual

components of the mix.

Powder mixing

• In practice, problems also arise because of the

inherent cohesiveness and resistance to movement

between the individual particles.

• The process is further complicated in many systems

by the presence of significant segregative influences

in the powder mix.

• These arise due to difference in particle size, shape

and density of the component particles.

Powder mixing

• This process of separation (segregation) occurs

during mixing as well as during subsequent handling

of the completed mix.

• The segregation process normally requires energy

input and can be reduced following mixing by careful

handling.

Wet granulation

• The most widely used and most general method of

tablet preparation is the wet granulation method.

• Its popularity is due to the greater probability that the

granulation will meet all the physical requirements

for the compression of good tablets.

Wet granulation

• Its chief disadvantages are the number of separate

steps involved as well as the time and labor necessary

to carry out the procedure, especially on large scale,

the steps in the wet method are weighing, sieving,

mixing, granulation, screening the damp mass,

drying, dry screening, lubrication and compression.

Wet granulation

• In wet granulation, after powder mixing, solution of

the binding agent is added. The powder mass is

wetted with the binding solution until the mass has

the consistency of damp snow or brown sugar.

• Different typed of binding agent used in wet

granulation are : purified water, absolute ethanol,

povidone solution, gelatin solution or starch paste.

Wet granulation

• Granulation is followed by wet milling in which

granules are forced through the sieving device by

rotating hammers, knives or oscillating bar. Why??

• Then the granules subjected to drying, fluid bed

drying is now considered the standard.

Wet granulation

• The strength of granules has also been shown to

influence the tensile strength of the tablets prepared

from them, with stronger granules leading, in general,

to harder tablets.

Wet granulation

• In drying granulation it is desirable to maintain a residual

amount of moisture in the granulation.(Why??)

• This is necessary to maintain the various granulation

ingredients, such as gum, in a hydrated state and hence

insure good binding between particles .

• Also, the residual moisture contributes to the reduction of

the static electric charges on the particles.

Wet granulation

• After drying, the granulation is reduced in particle

size by passing it through a smaller mesh screen, the

granules tend to be more uniform.

• Then the lubricant is added as fine powder after

screening through a mesh.

• As it is not desirable for each granule to be covered

with lubricant, the lubricant is blended with the

granulation very gently.

Dry granulation

(slugging)

• When tablet ingredients are sensitive to moisture or

unable to withstand elevated temperatures during

drying, and when the tablet ingredients have

sufficient inherent binding or cohesive properties,

slugging may be used to form granules.

• This method is referred to as dry granulation,

precompression or double compression.

Dry granulation

(slugging)

• It eliminates a number of steps but still includes

weighing, mixing, slugging, dry screening,

lubrication and compression.

• When slugging is used, large tablets are made as

slugs because fine powders flow better into large

cavities.

• Also production large slugs decreases production

time and also decrease the consumption of resources.

Direct compression

• For obvious reasons, the possibility of compressing

mixed powders into tablets without an intermediate

granulation step is an attractive one.

Direct compression

• It is possible to distinguish two types of Direct

compressed (DC) formulation:-

• (a) Those were the a major proportion is an

active ingredient,

• and (b) Those where the active ingredient is a

minor component.

Direct compression

• In the former case (high active), the inherent

characteristics of the drug molecule, in particular the

ability to prepare a physical form that will tablet directly,

will have profound effects on the tablet’s characteristics.

• It may sometimes be necessary to supplement the

properties of the drug so that it compresses more easily,

and these needs have been realized by several

manufacturer of excepients.

Direct compression

• Materials described as “compression aids” are now

commercially available.

• Ideally, such adjuvants should develop mechanical

strength while improving, or at least not adversely

affecting, release characteristics.

• Among the most successful at meeting both these

needs have been the microcrystalline cellulose

(MCC).

Direct compression

• Most other DC excepients really belong in the second

category, where the drug is present in low

concentration.

• In such cases the use of an expensive diluents is

warranted.

Tablet testing

or tablet qualifications

• Tablets may be characterized or described by a

number of specifications. These include the

following:

1. APPEARANCE

• The general appearance of tablets is an important

factor in consumer acceptance.

• It also allows monitoring of lot- to- lot uniformity,

tablet- to- tablet uniformity, and element of

manufacturing process.

• The appearance of the tablets includes visual identity

and overall appearance.

1. APPEARANCE

• The appearance of tablet is controlled by

measurement of attributes such as size, shape, color,

odor, taste, texture, physical flaws, consistency and

legibility of markings.

2.TABLET HARDNESS

• The mechanical strength of tablet dosage form is an

important property and it plays a significant role in

product development.

• The resistance of the tablet to chipping, abrasion, or

breakage under condition s of storage, transportation

and handling before usage depends on its hardness.

2.TABLET HARDNESS

• Tablet hardness is the force necessary to cause a tablet to

fracture when compressed between two rigid platens.

• Tablet strength is influenced by formulation component,

the processing used to make the formulation, and the

process of forming the compressed tablets.

• Tablet hardness tester is used to perform this test, it

measures the degree of force required to break a tablet.

3.TABLET FRIABILITY

• Tablet must be hard enough to withstand the agitation

and stress that occurs during manufacturing, coating,

packaging, shipping, and patient use.

• However, tablets must also be friable enough to

breakup when swallowed.

3.TABLET FRIABILITY

• Friability is the tendency of the tablet to crumble.

• Friabilators determine friability by allowing the

tablet to roll and fall within a rotating tumbling

apparatus.

• The tablets are weighed before and after a specified

number of rotations, and the weigh loss is

determined.(Pharmacopia limits: >1%)

4.UNIFORMITY OF DOSAGE FORM

1. Tablets weight:

• The weigh of the tablet is the quantity of the

granulation that contain the labeled amount of the

therapeutic ingredient.

• The USP has provided tolerances for the average

weight of uncoated compressed tablets.

2. Tablets weight:

Average weight Percent differences

130 mg or less 10

More than 130 mg

through 324 mg 7.5

More than 324 mg 5

Tolerances for the average weight of uncoated compressed

tablets.

2. Content uniformity

• To ensure that every tablet contains the amount of

drug substance intended, with little variation among

tablets within a batch, the USP includes the content

uniformity test for certain tablets.


• In general the content uniformity USP test is designed

to establish the homogeneity of a batch by assaying

10 tablets individually, after which the arithmetic

mean and Relative Standard Deviation (RSD) are

calculated.


• The USP criteria are met if the content uniformity lies

within 85 to 115% of the label claim, and the RSD is

not greater than 6%.

• Provision is included in the compendium for

additional testing if one or more units fail to meet the

standards.

5. Tablet disintegration

• To be absorbed, a drug substance must be in solution,

and the disintegration test is a measure only of the

time required under a given set of condition for a

group of tablets to disintegrate into particles.

• Thus the disintegration time is the time it takes for a

dosage form to break apart upon exposure to water

with mild agitation.

5. Tablet disintegration

• For conventional immediate release tablets,

disintegration times may range from less than 1 min

to as much as 5 to 15 min (the max in pharmacopias).

• The disintegration time is markedly affected by

formulation ingredients and processing.

• However, disintegration time does not necessarily

bear a direct relationship to in vivo release of drug

from a dosage form.

6. Tablet dissolution

• Dissolution refers to the process by which a solid

phase (e.g. tablet) goes into a solution phase such as

water or gastrointestinal fluid.


• If the dosage form is intended to disintegrate, the

tablet disintegrates into granules and these granules

disaggregate, in turn, into fine particles that disperse

in the dissolution medium.

• The individual particles then separate and dissolve

(e.g. mix molecule by molecule) with the liquid.


• Disintegration disaggregation and dissolution may

occur simultaneously with the release of a drug from

its delivery form.

• Some kinds of controlled release dosage forms are

not intended to fully disintegrate on exposure to fluid

but rather to slowly release drug from the dosage

form over a period of time.


• Drug dissolution is therefore the process by which

drug molecules are liberated from a solid phase and

enter into solution.

• If particles remain in the solid phase once they are

introduced into a solution, a pharmaceutical

suspension results.


• In the vast majority of circumstances, only drugs in

solution can be absorbed, distributed, excreted, or

even produce a pharmacologic action.

• Thus dissolution is an important process.


• The bioavailability of drugs from tablets can be

markedly influenced by the rate and efficiency of the

initial disintegration and dissolution process.

• Some of the reasons why dissolution testing is

important include:


• 1- Product optimization:

• By conducting dissolution studies in the early stage of

product’s development, differentiations can be made

between formulation and correlations identified with

in vivo bioavailability data.


• 2- Monitoring manufacturing process:

• The conduct of such testing from the early product

development through product approval and

commercial batch production assures the control of

any potential variables of materials and processes that

could affect drug dissolution and product’s quality

standards.


• 3- In vivo- in vitro correlation:

• In assessing such batch- to- batch bioequivalence, the

FDA allows manufacturer to examine scale up

batches of 10% of the proposed size of actual

production batch, or 100,000 dosage units, whichever

is greater.


• 4- Regulatory requirements:

• New drug applications contain in vitro dissolution

data generally obtained from batches that have been

used in pivotal clinical or bioavailability studies and

from human studies conducted during product

development.

• Once these specifications are approved they become

official specifications for all subsequent batches and

bioequivalent products.


• The goal of in vitro dissolution testing is to provide as

far as is possible, a reasonable prediction of, or

correlation with the product’s in vivo bioavailability.


• The USP includes seven apparatus designs (Table 2) for

drug release and dissolution testing for several dosage

forms.

• Dissolution testing should be carried out under

physiological conditions. if possible. The testing

conditions should be based on physicochemical

characteristics of the drug substance and the

environmental conditions the dosage form might be

exposed to after oral administration.


• The volume of the dissolution medium generally

500,900 or 1000 ml.

Type of apparatus When best used

Apparatus 2 (paddle) Default apparatus

Apparatus 1 (basket) Preferred over paddle for enteric coated

or beads.

Apparatus 3

(reciprocating

cylinder)

Low solubility compound when

surfactant concentration is

excessive.

Apparatus 4 (flow-

through)

Enteric coated dosage form, low

solubility compounds, other

strategies requiring a switch over in

media.

Types of Dissolution Apparatus Most Commonly Used to Test Solid

Dosage Form:


• All dissolution tests for immediate release dosage

forms should be conducted at 37± 0.5 ºc. The basket

or paddles are rotated between 50 to 150 rpm. The

basket and paddle method can be used for performing

dissolution tests under multimedia conditions (e.g. the

initial dissolution test can be carried out at pH 1.2,

and, after a suitable time intervals, a small amount of

buffer can be added to raise the pH to 6.8).

7. Tablet thickness

• The thickness of tablets from production- run to

production- run is controlled carefully. Thickness

varies with no change in weight because of difference

in the density of the granulation and the pressure

applied to the tablets, as well as the speed of tablet

compression.

7. Tablet thickness

• Not only is the tablet thickness important in

reproducing tablet identical in appearance but also to

ensure that every production lot will be usable with

selected packaging components. Tablet thickness also

becomes an important characteristic in counting

tablets using filling equipment.

7.Tablet thickness

• Tablet thickness is determined with a caliper or

thickness gauge that measures the thickness in

millimeters. Plus or minus 5% may be allowed

depending on the size of the tablets.

Tablet Press

• Mechanism of compression:

• Station: govern the tablet shape and size.

– Upper punch: Applied compression forces.

– Die : where the powder feed.

– Lower punch: control the weigh, and responsible

for tablet ejection.

Tablet Press

• Types:

1. Single punch press.

• R&D

Tablet Press

2. Rotatory press:

• Production

purpose.

Tablet Press

Tablet Press

2. Computerized hydraulic press:

• Movement of punches can be controlled.

• Tablet can be prepared under controlled condition

with respect to loading rate and loading pattern.

• Research purpose.

Tablet coating

• Three main types:

1. Film coating.

2. Sugar coating.

3. Enteric coating.

Tablet coating

• Reason for coating:

1. Protection from the environment.

2. Mask bitter taste.

3. Elegant appearance.

4. Identification for both the manufacturer and the

consumer.

5. Therapeutic uses (enteric).

Tablet coating

• The process carried out by spraying the tablet bed by

the coating solution. (Most Commonly used method)

Tablet coating

Tablet coating

• Coating suspension usually consist of :

1. Polymer: Soluble, viscous and permeable.

2. Plasticizer: decrease film brittleness.

3. Colorants: Water- insoluble; since they are

chemically stable.

4. Solvents: organic since it is environmentally

acceptable and safe

Reference

• Remington: The Science and Practice

of Pharmacy

Thank you

tablets - national university

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