Journal of Pharmacy Research Vol.1.Issue 1. July-September 2008 Novel Pharmaceutical Approaches For Colon- Specific Drug Delivery: An Overview

Colon specific drug delivery has gained increased importance not just for the delivery of drugs in the treatment associated with the colon, but also as a potential site for the systemic delivery of therapeutic peptide and proteins. To achieve successful colon targeted drug delivery, a drug needs to be protected from degradation, release and/or absorption in the upper portion of the GI tract and then to be ensured abrupt or controlled release in the proximal colon. The necessity and advantages of colon-specific drug delivery systems have been well recognized and documented. The primary approaches to obtain colon-specific delivery are based on prodrugs, pH- and time-dependent systems or microflora-activated systems and have achieved limited success only. Precise colon drug delivery requires that the triggering mechanism in the delivery system only respond to the physiological conditions particular to the colon. Hence, continuous efforts have been focused on designing colon-specific delivery systems with improved site specificity and versatile drug release kinetics to accomplish different therapeutic needs. Among the systems developed most recently for colon-specific delivery, four systems were unique in terms of achieving in vivo site specificity, design rationale, and feasibility of the manufacturing process (pressure-controlled colon delivery capsules (PCDCs), CODES™, colonic drug delivery system based on pectin and galactomannan coating, and Azo hydrogels). The focus of this review is to provide detailed descriptions of the above mentioned approaches