Design Development and Evaluation of Acyclovir Loaded Compressed Microsponge
Abstract
The Microsponge Drug Delivery System (MDS) is a patented technology has been successively used for the controlled release of topical agents which consist of macro porous beads, typically 10-25 microns in a diameter, which are loaded with active agent. Allowing a sustained flow of substances out of the sphere, the outer surface is typically porous, This system can suspend or entrap a wide variety of substances, and incorporated into a formulated product such as a liquid, gel, cream, or powder. The Microsponge shows time mode release when applied to the skin and they also response to otherstimuli like rubbing, pH, etc. MDS technology is currently used in different dosage forms like cosmetics, over the counter (OTC) skin care, sunscreens and prescription products. Microsponge technology allows entrapment of ingredients and it also shows reduced side effects, more stability, increased elegance and enhanced formulation flexibility. In addition, various studies have showed that microsponge systems are non-irritating, non-mutagenic, non-allergenic, and non-toxic. Microspheres can be prepared by different methods using emulsion system or by suspension polymerization in liquid system.
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Introduction
1.1 The Microsponge Delivery System
A Microsponge drug delivery system (MDDS) is a patented, highly cross-linked, porous, polymeric microspheres polymeric system (10-25 µ) consisting of porous microspheres particles consisting of a myriad of inter connecting voids within noncollapsible structures with a large porous surface that can entrap wide range of actives (cosmetics, over-the-counter (OTC) skin care, sunscreens and prescription products). A typical 25 µm sphere can have up to 250000 pores and an internal pore structure equivalent to 10 ft in length providing a total pore volume of about 1ml/g. Microsponge technology offers entrapment of ingredients and is believed to contribute towards reduced side effects, increased efficacy, improved stability, increased elegance and enhanced formulation flexibility.[3,31,32] In addition, numerous studies have confirmed that microsponge systems are non- irritating, non- mutagenic, non-allergenic and non-toxic.
The microsponge drug delivery system (MDS) releases its active ingredient on a time mode and also in response to other stimuli (rubbing, temperature, pH, etc.) Microsponges have the capacity to absorb or load a high degree of active materials into the particle or onto its surface. Its large capacity for entrapment of actives up to 3 times its weight differentiates microsponges from other types of dermatological delivery systems. The MDS has advantages over other technologies like microencapsulation and liposomes. Microcapsules cannot usually control the release rate of actives. Once the wall is ruptured the actives contained within microcapsules will be released. Microsponges are stable over range of pH 1 to 11, temperature up to 130oC, compatible with most vehicles and ingredients, self sterilizing as average pore size is 0.25 μm where bacteria cannot penetrate, higher payload (50 to 60%), still free flowing and can be cost effective. Most liquid or soluble ingredients can be entrapped in the particles.
The Microsponges are prepared by different methods using emulsion systems as well as by suspension polymerization in a liquid–liquid system. The most common emulsion system used is oil-in-water (o/w), with the microsponges which are produced by the emulsion solvent diffusion method.[33]
Conclusion
1) Microsponge containing Acyclovir was prepared by Quasi-emulsion diffusion method using Eudragit RS 100 and ES100 polymers.
2) All the microsponge formulations were subjected for the drug content estimation and loading efficiency. The drug content was uniform and reproducible in all the formulations.
3) The IR spectral analysis suggested that there were no interaction between the drug and formulation additives.
4) Internal Phase Volume: As there is increase in the internal phase volume, there is decrease in the Particle Size, Drug Content and Entrapment Efficiency and there is Increase in the free drug content.
5) Polymer Concentration: As Polymer concentration increases, the drug release decreases.
6) Surfactant Concentration: As surfactant concentration increases, there is increase in the particle size and, decrease in the encapsulation efficiency and the production yield and larger microsponges.
7) External Phase Volume: As there is increase in the external phase volume, there is decrease in drug content, drug entrapment and increase in the free drug content and particle size.
8) Rate of stirring: As stirring speed increases there is increase in the free drug content and there is decrease in the drug content, entrapment efficiency and particle size.
9) Time of stirring: As stirring time increases there is decrease in the free drug content, particle size and there is increase in the entrapment efficiency and drug content.
10) Drug: Polymer Ratio: As there is increase in the drug: polymer ratio, there is increase in the encapsulation efficiency and the production yield, decrease in the particle size.
11) The dissolution was carried out of all the batches.