drug delivery system, Lecture notes of Biopharmaceutics and Pharmacokinetics

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CONVENTIONAL AND NOVEL DRUG

DELIVERY SYSTEM

By: ZILLE ALI Department of Pharmaceutics IIT(BHU) [email protected]

CONTENTS

 (^) DRUG DELIVERY SYSTEM  (^) CONVENTIONAL DRUG DELIVERY SYSTEM  (^) NOVEL DRUG DELIVERY SYSTEM

CONVENTIONAL DRUG DELIVERY SYSTEM

Conventional Drug Delivery System is the Classical methods for the delivery of Drug into the body. The Examples of these systems includes:  (^) Oral Delivery  (^) Buccal / Sublingual Delivery  (^) Rectal Delivery  (^) Intravenous Delivery  (^) Sub Cutaneous Delivery  (^) Intramuscular Delivery

Oral Delivery It includes tablets, capsules, syrups etc. taken directly through mouth and travels through GIT. Advantages of Oral Delivery:  (^) Convenience in Administration  (^) Non invasive  (^) Accurate and measured dose.  (^) Unit Dosage form  (^) Higher compliance  (^) Cheap to the patient. Disadvantages of Oral Delivery:  (^) Unconscious patients cannot take dose  (^) Low permeability.  (^) Degradation by Gastro-Intestinal enzymes.  (^) First pass metabolism  (^) Irregular absorption

Rectal Delivery Here suppositories are placed inside rectum and it melts at body temperature to give quick effect. Advantages  (^) By-pass first pass metabolism  (^) Useful for children Disadvantages  (^) Absorption depends on disease state  (^) Degradation by bacterial flora  (^) Uncomfortable

Intravenous Delivery Drug in liquid form is administered directly into blood by injecting in vein with the help of sterile injector. Advantages  (^) Drug 100% bioavailable  (^) Rapid response  (^) Can administer drugs degradable in stomach.  (^) By-passes First Pass Metabolism Disadvantages  (^) Invasive  (^) Trained personnel  (^) Possible toxicity due to incorrect dosing  (^) Sterility

Intramuscular Delivery The liquid drug is administered in the muscle tissue by injecting with injector. Advantages  (^) Drug is absorbed slowly, so prolong effect.  (^) Larger volume than subcutaneous  (^) By-pass first pass metabolism Disadvantages  (^) Invasive – patient discomfort  (^) Irritation,  (^) Inflammation  (^) May require some training

NOVEL DRUG DELIVERY SYSTEM (NDDS)

It is a combination of advance technique and new dosage forms which are far better than conventional dosage forms and involves medicinal devices. It improves drug potency, control drug release to give a sustained therapeutic effect, provide greater safety and target a drug specifically to a desired tissue. Advantage of NDDS over conventional  (^) The conventional dosage forms provide drug release immediately and it causes fluctuation of drug level in blood depending upon dosage form.  (^) Therefore to maintain the drug concentration within therapeutically effective range need novel drug delivery system.

Controlled Drug Delivery System Release of drug is for long periods. In this the rate or speed at which the drug is released is controlled by modification in formulation. e.g. Nifidipine. Modulated Drug Delivery System Here the rate of drug release is controlled and modulated by devices such as nebulizer, MDI (metered dose inhaler) etc.

Classification of NDDS with

reference to release control

1. Matrix Diffusion Types: Here rate of release is controlled by diffusion of dissolved drug in the matrix.  (^) Rigid Matrix Diffusion : Here insoluble plastic materials like PVP & fatty acids are used.

 (^) Swellable Matrix Diffusion : Here gums are used. These are also called Glassy Hydrogels and popular for sustaining the release of highly

water soluble drugs.

 (^) Reservoir System: Here polymer content in coating, thickness of coating & hardness of micro-capsules control the release of the drug.

2. Dissolution Matrix Type Here drug is homogeneously dispersed in rate controlling waxy medium like bees wax, castor oil etc. . (^) Encapsulation: Dissolution is controlled by coating system like use of cellulose, Polyethylene Glycols, polymethylacrylates, and waxes. Dissolution rate also depend upon coating material stability and thickness of coating film.

7. Ion Exchange Resins Controlled Release Systems: Here ionisable drug is absorbed on ion-exchange resins granules then granules are coated with water permeable polymers using spray dryer technique. List of drug carrier in NDDS  (^) Nanosomes  (^) Liposomes  (^) Niosomes  (^) Nanoparticle  (^) Nanosphere  (^) Microsphere  (^) Microparticle  (^) Microemulsion  (^) Nanosuspension  (^) Micelles

Advantages of NDDS  (^) Decreased dosing frequency.  (^) Reduced rate of rise of drug concentration in blood.  (^) Sustained and consistent blood level within the therapeutic window.  (^) Enhanced bioavailability.  (^) To achieve a targeted drug release.  (^) Reduced side effects.  (^) Improved patient compliance.