Applications of Polymers in Formulation of Controlled Drug Delivery System

Osmotic Pressure-Controlled GI Delivery System 

A semi-permeable membrane is made from biocompatible polymers.  E.g. cellulose acetate 

Examples of such type of system include Acutrim tablet which contains Phenylpropanolamine as a drug. 

In this device, an osmotic agent is contained within a rigid housing and is separated from an active agent compartment-b, a movable partition. One wall of the rigid housing is a semipermeable membrane so that when the pump is exposed to an aqueous environment, water will be driven osmotically across the membrane, the increased volume within the osmotic compartment will force the active agent out of the device through the delivery orifice. A major application is for gastro-intestinal drug deliveries because the delivery rate is pH-independent.

Osmotic Pressure-Controlled GI Delivery System 
Fig.1: Osmotic Pressure-Controlled GI Delivery System 

Gel Diffusion Controlled GI Delivery System 

Diffusion and Dissolution-Controlled Release System: 

  1. The drug is encased in a partially soluble membrane. 
  2. Pores are created due to the dissolution of parts of the membrane. 
  3. It permits entry of aqueous medium into core and drug dissolution. 
  4. Diffusion of dissolved out of the system. 

Example: Ethylcellulose and PVP mixture dissolves in water and creates pores of insoluble ethylcellulose membrane.

Gel Diffusion-Controlled GI Delivery System
Fig.2: Gel Diffusion-Controlled GI Delivery System

Mucoadhesive GI Delivery System 

The new generation mucoadhesive polymers for buccal drug delivery with advantages such as; increase in the residence time of the polymer, penetration enhancement, site-specific adhesion, and enzymatic inhibition, site-specific mucoadhesive polymers will undoubtedly be utilized for the buccal delivery of a wide variety of therapeutic compounds. The class of polymers has enormous potential for the delivery of therapeutic macromolecules.

Mucoadhesive GI Delivery System
Fig.3: Mucoadhesive GI Delivery System

Transdermal Drug Delivery System 

TDDS is defined as, self-contained, self-discrete dosage forms, which when applied to the intact skin, deliver the drug at a controlled rate to the systemic circulation. In this, polymer matrix plays a major role. It releases the drug from the device to the skin.

Advantages of Transdermal Drug Delivery System: 

  • They permit easy removal and termination of drug action in situations of toxicity.
  • Problems encountered with oral administration like; degradation, gastric irritation, etc. are avoided. 
Transdermal Drug Delivery System 
Fig.4: Transdermal Drug Delivery System 

Ocular Drug Delivery System 

It allows prolonged contact of the drug with the corneal surface of the eye. An example of ODDS is pilocarpine in the treatment of glaucoma. In this, mucoadhesive polymers are used as barriers to control the drug release. E.g. Polyacrylic acid, Copolymers of acetate vinyl, and ethyl. 

Ocular Drug Delivery System 
Fig.5: Ocular Drug Delivery System 

Other Applications 

1. Drug Delivery and the Treatment of Diabetes:  Here the polymer will act as a barrier between the bloodstream and insulin. E.g. Polyacrylamide or N, N-Dimethyl amino ethylmetha acrylate.

Drug Delivery in the Treatment of Diabetes 
Fig.6: Drug Delivery in the Treatment of Diabetes 

2. Drug Delivery of Various Contraceptives and Hormones 

It consists of a drug saturated liquid medium encapsulated in a polymeric layer which controls the concentration and release of drugs into the bloodstream.  E.g. Medoxy progesterone acetate, Progestasert, Duromine, etc.

Drug Delivery of Various Contraceptive and Hormones
Fig.7: Drug Delivery of Various Contraceptive and Hormones
Make sure you also check our other amazing Article on : Role of Polymers in Drug Delivery
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