Microsponges ~ A Malleable Drug Delivery System

Introduction:

Microsponges are at the forefront of the rapidly developing field of novel drug delivery technology. Microsponges are defined as polymeric delivery systems made up of porous microspheres. They are small sponge-like globular particles with a huge porous surface. Microsponges technology has lot of advantageous & innovative characteristics, which make it a flexible drug delivery vehicle. Microsponges can be restrained in a wide range of substances, and can then be incorporated into a formulated product such as a cream, gel, powder or liquid. The outer surface is usually porous, permitting a uniform flow of medicaments out of the sphere for a pronged period. Microsponges are used largely for topical purpose and nowadays have been used for oral administration. Microsponges are aimed to deliver a pharmaceutically active ingredient capable at the minimum dose and also to increase stability, lower the side effects and improve drug release favorably.

Methods of Preparation:

·         Liquid-Liquid suspension polymerization

·         Quasi emulsion solvent diffusion

·         Free radical suspension polymerization

Types:

·         Microsponges for topical delivery

·         Microsponges for oral delivery

 Properties:

·        It must be either completely soluble in the monomer or ready for being made soluble by addition of a little amount of water-immiscible solvent.

·        It must be water unmixable or at most only faintly soluble.

·      It must be chemically inert to monomers and should not enhance the viscosity of the compound during formulation.

·   It must be persistent during contact with a polymerization catalyst and under medium of polymerization.

·        The round structure of the Microsponges should not flop.

 Applications:

·   Sunscreens – prolonged product activity, with enhanced protection against sunburns and sun-related wounds and sufferings even at raised concentration and with lower irritancy and sensitization

·   Anti-acne – e.g. Benzoyl peroxide Maintained activity & efficiency with reduced skin irritation and sensitization.

·    Anti-inflammatory – e.g. hydrocortisone prolonged action with the lower response of skin allergy and dermatomes.

·   Anti-dandruff – e.g. zinc pyrithione, selenium sulfide Decrease in unpleasant odor with reduced irritation with enhanced safety and efficacy.

·       Antipruritic – Expanded and improved activity.

·  Skin Depigmenting agents - e.g. hydroquinone Improved stabilization against oxidation with improved efficacy and aesthetic appeal.

·       Antifungal – Log lasting releasing activity.

·    Rubefacients – Sustained activity with lower irritancy, odor & greasiness.