Microsponges - a new perspective in colon targeted drug delivery systems

Abstract

Colon specific drug delivery is a preferable route of administration for drugs used in the treatment of local diseases associated with the colon, drugs with significant gastro-intestinal side effects, pH-sensitive or sensitive to enzymatic degradation molecules or drugs which therapeutic activity requires the use of delayed-release dosage forms. Colon as a specific site of drug delivery provides reduced digestive enzymatic activity, pH values near neutral and much longer transit time compared to the stomach and small intestine. Several approaches are developed to achieve colon targeted drug delivery based on pH-sensitivity, time-dependency, prodrug formulation, microbial degradation, osmotic pressure and ect. Use of multiparticulate formulations, such as microsponges, in colon site-specific drug delivery systems (CDDS) achieves uniform distribution at the target region, higher bioavailability and lower risk of dose-dumping and local irritation. Microsponges are microporous polymeric microspheres which have the flexibility to entrap a wide range of therapeutic agents within a non-collapsible structure. The sponge-like microspheres serve as a reservoir which releases the drug in controlled manner through the pores and allows extended action up to 12 hours. Moreover, microsponges can potentially enhance the stability and solubilization of poorly soluble drugs, achieve efficacy at the minimum dose, reduce side effects and improve therapy results. These and other advantages of microsponges arouse interest in their application as drug carriers in CDDS.