Over the past decade, numerous limitations of conventional dosage forms had attracted researchers to find a rational and appropriate drug delivery system. Microsponges were developed and studied as a novel programmable delivery system which is intended to deliver drug in controlled release pattern. It also aims epidermal localization of topical drug therapy to reduce their side effects by limiting systemic absorption through skin. Drug loaded microsponges are microporous beads, typically 10-25 µm in diameter which can entrap a wide variety of actives and can be formulated as creams, lotions, gels, ointments, powders, soaps. Microsponge formulations can increase product stability, enhance aesthetic qualities, and provide formulation flexibility and stability. Moreover, their non-antigenicity, non-toxicity, non-mutagenicity and non-biodegradability make them favourable candidates. Microsponge approach has also been applied in oral therapy, bone, tissue & cartilage engineering and showed remarkable results. This article provides description about the nature of microsponges, their characteristics, preparation, applications and commercial market status globally.
Keywords: Microsponges, topical delivery, controlled release, quasi-emulsification, programmable release
With the advent of 21st century, numerous technologies and advancements had been developed for delivery of drugs and medicaments using skin as a portal. Human skin is a large multilayered organ which serves as a barrier against physical and chemical attack, maintains body temperature and blood pressure, and prevents microbial invasion etc. Several topical dosage forms have been developed for either local action or systemic effect such as creams, ointments, gels, lotions, transdermal patches etc. But their efficacy is still under question.
Undesirable penetration of topical agents like corticisteroids or sunscreens, can lead to systemic side effects of adrenal suppression and irritancy or allergic reactions. To overcome such problems, novel approaches have been studied and considerable emphasis have been laid on microsponges based drug delivery to facilitate epidermal localization and control drug release by incorporation into a carrier system so as to alter the therapeutic index and duration of the activity of drugs. Microsponges are polymeric delivery systems composed of porous microspheres whose size may vary usually from 5-300 μm in diameter, depending upon the degree of smoothness or after-feel required for the end formula. 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 1 ml/g. They are biologically inert particles that are made of synthetic polymers and protect the entrapped drug moiety from physical and environmental degradation. Their high degree of cross-linking make them insoluble, inert and have sufficient strength to withstand high shear commonly...