Cyclodextrin Inclusion Complex to Enhance Solubility of Poorly Water Soluble Drugs: a Review

Low solubility compounds show dissolution rate limited absorption and hence poor absorption, distribution and target organ delivery. Improvement of aqueous solubility in such a case is valuable goal to improve therapeutic efficacy. Complexation with CDs by different methods like physical mixing, melting, kneding, spray drying, freeze drying, co-evaporation has been reported to enhance the solubility, dissolution rate and bioavability of poorly water soluble drugs. The formation of inclusion complex can be confirmed by DSC, FTIR, XRD and SEM study. This review aims to assess the use of cyclodextrines as complexing agents to enhance the solubility of poorly soluble drugs and hence to resolve the many issues associated with developing and commercializing poorly water soluble drugs. INTRODUCTION: To be pharmacologically active, all drugs must possess some degree of aqueous solubility, and most drugs should be lipophilic to permeate the biological membranes via passive diffusion. The poor solubility and low dissolution rate of poorly water soluble drugs in the aqueous gastro-intestinal fluids often cause insufficient bioavailability . Poorly water-soluble compounds with dissolution ratelimited low oral bioavailability present one of the major challenges in pharmaceutical formulation development . To be pharmacologically active, all drugs must possess some degree of aqueous solubility, and most drugs should be lipophilic to permeate the biological membranes via passive diffusion . The water solubility of any drug is determined by its potency and its type of formulation 4, 5, 6 . For pharmacological response to be shown the solubility is one of the important parameter to achieve desired concentration of drug in systemic circulation. The BCS is a scientific framework for classifying a drug substance based on its aqueous solubility and intestinal permeability. When combined with the in vitro dissolution characteristics of the drug product, the BCS takes into account three major factors: solubility, intestinal permeability, and dissolution rate, all of which govern the rate and extent of oral drug absorption 7, 8, . Poorly water-soluble drug candidates often emerge from contemporary drug discovery programs, and present formulators with considerable technical challenges. The poor solubility and low dissolution rate of poorly water soluble drugs in the aqueous gastrointestinal fluids often cause insufficient bioavailability.