BIOADHESIVE DRUG DELIVERY SYSTEMS

• Handbook of experimental pharmacology,DRUG DELIVERY,

• Hofman , Munchen

Adhesion

• Bond produced by contact between a pressure- sensitive adhesive and a surface. Ability tostick, adhere or hold

• Bioadhesion is defined as an ability of amaterial to adhere to a biological tissue for anextended period of time. Attachment ofsynthetic or biological macromolecules to abiological tissue.

Muco-adhesion

• In higher organisms epithelia are covered bya protective gel layer defined as mucus. Theterm muco-adhesion refers to the special caseof bio-adhesion where the biological tissue isan epithelium covered by mucus.

• Mucus is a thin blanket covering all epitheliathat are in contact with the externalenvironment

The mucosal routes • Buccal/oral route• Nasal route• Ocular route• Vaginal route• Gastrointestinal route

• Moreover the muco-adhesive material itself canalso be a therapeutic agent for tissue protection(e.g., gastric ulcers) or lubrication (in the eye orvagina).

Reason • Drug absorption is often limited by the residence time of

the drug at the site of absorption.– In ocular delivery, for example, a drug solution is

cleared by the lacrimal fluid within a few minutesafter application.

• Therefore muco-adhesion is an important strategy inorder to prolong the mucosal residence time of drugdelivery systems.

Mucus • The function of mucus is mainly the protection

and lubrication of the underlying epithelium, butit may have additional functions dependent onthe type of the covered epithelia

• Both systemic and local delivery can beoptimized with muco-adhesive dosage forms byretaining in intimate contact with the absorptionsite or the site of action, which results in highlocal drug concentrations and a high fluxthrough the absorbing tissue.

STRUCTURE OF MUCIN

Step 1:Swelling

Step 2:interpenetration

Bioadhesivepolymer chains

Mucuspolymer chains

Inter-diffusion and Interpenetration of Polymer and Mucus

Types of Bioadhesive DDS

THEORIES OF MUCOADHESION:-

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Summary Wetting and swelling of the polymer permit intimate contact with

the biological tissue. Interpenetration of bioadhesive polymer chains and entanglement

of polymer and mucin chains. Formation of weak chemical bonds. Sufficient polymer mobility to allow spreading. Water transport followed by mucosal dehydration . The bioadhesive coated system when comes in contact with the

mucus layer, various non-specific or specific interactions occursbetween the complimentary structures and these interactions lastonly until the turnover process of mucin

the drug delivery system should release its drug contents duringthis limited adhesion time, in order for a bioadhesive system to besuccessful.

FACTORS AFFECTING MUCOADHESION

Bioadhesive nature of polymers

EXCELLENT MODERATE POORCMC+++ Gelatin ++ Pectin +

HPMC+++ Guar gum ++ Acacia +

Carbopol 934 +++ Gum karaya ++ PVP +

Tragacanth +++

Sodium alginate +++

Polycarbophil +++

Hydroxyl ethyl cellulose +++

Different routes of targeting Bdds

Depending upon the route of administration of the mucoadhesive drugs they are different types .

1)Buccal DDS

2)Ocular DDS3)Nasal DDS

4)Vaginal DDS5) Rectal DDS

6)Pumonary DDS

7)GI DDS

BUCCALDELIVERY

Salivation

Michael J. Rathbone. Oral mucosal drug delivery. Marcel Dekker, Inc. 1996.

Substances that reduce salivary secretion would be expected to increase drug concentrations in the oral cavity.

encyclopedia

Research

• Mucoadhesive control test?

NASAL DELIVERY

NASAL DRUG DELIVERY

22-Apr-

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ANATOMY & PHYSIOLOGY OF NASAL

CAVITY

22-Apr-

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Fig:1

Mucoadhesive Carrier

Hydration and swell of polymer

Hydrophilic Macromolecular drug

Internal Absorption

Interaction with Mucus

Drug release

Enzymatic MetabolismCilliary clearance

Fig:2 Scheme of Mucoadhesive Nasal Drug Delivery39

OCULAR DELIVERY

VAGINAL DELIVERY

@

• Several market preparations like are also available.• ESTERING vaginal ring – PHARMACIA & UPJHON

(Estradiol)

@

• CERVIDIL: it is a vaginal insert of dinoprostone. It contains 10mg of drug and release the drug at the rate of 0.3 mg/hr. it cangive continuous release for up to 12 hrs.

• Fig . CERVIDIL

Vaginal Films

Vaginal films are polymeric drug delivery systems shaped as thin sheets,usually ranging from 220 to 240 μ m in thickness.

These systems are often square (approximately 5 cm × 5 cm), colorless,and soft, presenting a homogenous surface.

Vaginal films are produced with polymers such as polyacrylates,polyethylene glycol, polyvinyl alcohol, and cellulose derivatives.

RECTAL DELIVERY

COLON DELIVERY

Disorders of Colon Inflammatory bowels disease (IBD)

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Enteric coated matrix tablet Enteric coated matrix

tablet in upper GI

Solubelization of enteric

coat and swelling of inner

matrix followed by

degradation by colonic

bacteria

Degradation of swelled

matrix tablet and drug

release

Behavior of Enteric-coated MatrixColonic

bacteria

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Bacteria in

colon

Hydrolysis of sulphasalazine (A) into 5-aminosalicylic acid (B)

and sulfapyridine (C).

(

A

)

(

B

)

(

C

)

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63

delivery of balsalazine

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Marketed formulations

delivery of olsalazine