ABSTRACT
Oral colon-specific drug delivery is important not only for the treatment of inflammatory bowel diseases, but it has other potential systemic and local applications. Targeting drugs to the colon is challenging and involves the exploitation of site-specific triggers. A major problem in comparing different delivery systems to the colon is that the degradation studies are carried out in different experimental conditions. Rationally developed evaluation methods can be used to assess drug release kinetics, the implications of formulation and manufacturing process changes, the impact of pH and hydrodynamic conditions on drug release characteristics, to elucidate drug-release controlling mechanism, to ensure batch to- batch consistency in manufacturing, and possibly to act as an in vivo surrogate. This necessitates that the methods be discriminative, reproducible, scientifically justifiable, and more importantly bio-relevant. This review discusses various in-vitro and in-vivo methods employed for evaluation of colon-specific drug delivery systems.
