Mucoadhesive Drug Delivery System

1. M U C O A D H E S I V E D R U G
D E L I V E RY S Y S T E M
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Dr. Prashant L. Pingale
Associate Professor, Dept. of Pharmaceutics
GES’s Sir Dr. M. S. Gosavi College of Pharm. Edu. & Research,
Nashik-422005, INDIA

2. CONTENTS AS PER SYLLABUS…
• Introduction,
• Advantages and disadvantages,
• Principles of bioadhesion / mucoadhesion,
• Concepts,
• Advantages and disadvantages,
• Transmucosal permeability and formulation considerations of buccal
delivery systems.
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3. INTRODUCTION
• Mucoadhesive drug delivery systems are delivery systems which utilize the
property of bioadhesion of certain polymers which become adhesive on hydration
and hence can be used for targeting a drug to a particular region of the body for
extended periods of time.
• Bioadhesion is an interfacial phenomenon in which two materials, at least one of
which is biological, are held together by means of interfacial forces.
• The attachment could be between an artificial material and biological substrate,
such as adhesion between a polymer and a biological membrane.
• In the case of polymer attached to the mucin layer of a mucosal tissue, the term
“mucoadhesion” is used.
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4. VARIOUS ROUTES
• Mucoadhesive drug delivery systems can be delivered by various routes:-
– Buccal delivery system
– Oral delivery system
– Vaginal delivery system
– Rectal delivery system
– Nasal delivery system
– Ocular delivery system
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5. MUCOADHESIVE ORAL DRUG DELIVERY SYSTEMS
• Oral route is the most preferred route for the delivery of any drug. Drug
delivery via the membranes of the oral cavity can be subdivided as:-
• Sublingual delivery: This is systemic delivery of drugs through the mucosal
membranes lining the floor of the mouth.
• Buccal delivery: This is drug administration through the mucosal
membranes lining the cheeks (buccal mucosa)
• Local delivery: This is drug delivery into the oral cavity.
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6. MUCOADHESIVE ORAL DRUG DELIVERY SYSTEMS
• Within the oral mucosal cavity, the buccal region offers an attractive route of
administration for controlled systemic drug delivery.
• Buccal delivery is the administration of drugs through the mucosal membrane lining
the cheeks.
• Although the sublingual mucosa is known to be more permeable than the buccal
mucosa, the latter is the preferred route for systemic transmucosal drug delivery.
• This is because the buccal mucosa has an expanse of smooth muscle and relatively
immobile mucosa, which makes it a more desirable region for retentive systems.
• Thus, the buccal mucosa is more appropriate for sustained direction of drug delivery.
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7. ADVANTAGES OF ORAL MUCOADHESIVE DRUG
DELIVERY SYSTEMS
• Prolongs the residence time of the dosage form at the site of absorption,
hence increases the bioavailability.
• Excellent accessibility, rapid onset of action.
• Rapid absorption because of enormous blood supply and good blood flow
rates.
• Drug is protected from degradation in the acidic environment in the GIT.
• Improved patient compliance.
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8. DISADVANTAGES OF MUCOADHESIVE DRUG
DELIVERY SYSTEMS
• Occurrence of local ulcerous effects due to prolonged contact of the drug
possessing ulcerogenic property.
• One of the major limitations in the development of oral mucosal delivery is
the lack of a good model for in vitro screening to identify drugs suitable for
such administration.
• Patient acceptability in terms to taste and irritancy.
• Eating and Drinking is prohibited.
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9. TRANSMUCOSAL PERMEABILITY
AND FORMULATIONS
• Transmucosal permeability refers to the transport of material such as drugs
across the oral mucosa.
• Transmucosal permeability is a unique approach that aims at delivering the
drug systemically through the oral mucosa.
• As an alternative to enteral delivery of drugs, this route of drug delivery is less
invasive.
• It doesn’t require much technical equipment.
• The main consideration with transmucosal delivery is that the absorption via
this route is variable.
• Thus, making it unsuitable for delivering low potent drugs.
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10. TRANSMUCOSAL PERMEABILITY:
METHODS FOR DRUG ABSORPTION
• Drugs traverse through the oral mucosa by different methods of absorption.
• Some of the commonly adopted routes are:
• Passive diffusion refers to the non – ionic diffusion of drugs from the high
concentration to the lower concentration and is the major absorption process.
• Facilitated diffusion – This is similar to passive diffusion but differs because it
uses integral transmembrane proteins to facilitate the transport.
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11. TRANSMUCOSAL PERMEABILITY:
METHODS FOR DRUG ABSORPTION
• Active transport – This transport requires energy for the drug’s movement
across the oral mucosa. The hydrolysis of ATP often provides the energy.
• Pinocytosis – In this type of transport, the entire drug molecule is engulfed
into the cell as a small vesicle. This process also requires energy in the
form of ATP.
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12. TRANSMUCOSAL PERMEABILITY:
METHODS FOR DRUG ABSORPTION
• The following factors must be considered, To ensure that the transmucosal route can
successfully deliver a drug. Factors affecting Transmucosal permeability are:
• Lipophilicity of the drug – The permeability is higher for agents or drugs that are highly lipid-
soluble.
• Salivary secretion – Higher the salivary secretion, the higher the drug’s chances of being
flushed out. This can lead to incomplete absorption of the drug.
• The saliva’s pH – Absorption is favored when the pH is around 6.
• Binding to the oral mucosa – Proper binding of the drug carrier to the oral mucosa is essential.
It helps permeates the drug across the mucosa to the systemic circulation.
• Oral epithelium thickness – The permeation rate of the drug from the drug carrier is
dependent on the thickness of the oral epithelium. The thicker this layer, the longer the
residence time of the drug. 12

13. FORMULATION CONSIDERATIONS OF THE
BUCCAL DELIVERY SYSTEMS
• Buccal delivery systems refer to the administration of
the drugs via the buccal mucosa.
• The buccal mucosa is the mucosa that lines the inner
cheek.
• Formulations targeting this region are placed in the
mouth between the upper gums and the cheek.
• This mucosa is highly vascularized and is relatively
easy to access.
• The absorption of drugs in this region mainly occurs
by passive diffusion into the lipoidal membrane.
• The various buccal formulations currently available in
the market are buccal tablets, buccal patches/films,
and buccal gels/ointments.
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14. MAIN FACTORS CONSIDERED IN FORMULATION
OF THE BUCCAL DELIVERY SYSTEMS
• The main factors that must be considered before formulating these buccal
delivery systems are :
• Size of the formulation – Formulations with a size of 1 to 3 cm2 and a
daily dose of 25 mg or less is preferred.
• The drug’s molecular weight – Drugs with high molecular weight cannot
readily permeate through the buccal mucosa. Hence low molecular weight
drugs are often preferred. To facilitate the delivery of the former,
penetration enhancers are used.
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15. MAIN FACTORS CONSIDERED IN FORMULATION OF
THE BUCCAL DELIVERY SYSTEMS
• Nature of the drug – Highly lipophilic drugs that can
passively diffuse through the buccal mucosa is used while
formulating buccal drug delivery systems.
• The pH of the formulation – The pH of the carrier used in
the system alters the drug’s absorption. Lowering the
carrier pH increases some drugs’ absorption, while the
opposite is true for other drugs.
• Physicochemical characteristics of the drug – The drug
should be odorless and not have an unpleasant taste.
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16. EXCIPIENTS USED FOR THE FORMULATION OF BUCCAL
DRUG DELIVERY
• Mucoadhesive polymers – These synthetic or natural polymers interact with the
mucosa’s epithelial surface to adhere to the mucosal layer. The commonly used
polymers in buccal dry or partially hydrated dosage forms are polyacrylic acid,
polyvinyl alcohol, sodium carboxymethyl cellulose, and sodium alginate.
• Penetration enhancers – These substances increase the buccal mucosal membrane
permeation rate. It also aids the delivery of drugs that have high molecular weight
and are easily inactivated. E.g., Sodium laurate, sodium taurocholate, oleic acid, and
chitosan, among others.
• Enzyme inhibitors – are added to prevent the degradation of the drugs, especially
peptides, or by the mucosal enzymes. These inhibitors also improve the drugs’
buccal absorption: Eg. Aprotinin, bestatin, puromycin, and bile salts.
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