Vol. 1, Issue 12 (2013)

Author(s):
Debjit Bhowmik, G.Harish, S.Duraivel, B. Pragathi Kumar, Vinod Raghuvanshi, K. P. Sampath Kumar

Abstract:
In recent years, the formulation of poorly soluble compounds presented interesting challenges for formulation scientists in the pharmaceutical industry. Up to 40% of new chemical entities discovered by the pharmaceutical industry are poorly soluble or lipophilic compounds, which lead to poor oral bioavailability, high intra and inter subject variability and lack of dose proportionality. This frequently results in potentially important products not reaching the market or not achieving their full potential. Poorly water-soluble drugs often require high doses in order to reach therapeutic plasma concentrations after oral administration. Improvement in the extent and rate of dissolution is highly desirable for such compounds, as this can lead to an increased and more reproducible oral bioavailability and subsequently to clinically relevant dose reduction and more reliable therapy. The enhancement of dissolution rate and oral bioavailability is one of the greatest challenges in the development of poorly water soluble drugs. Dissolution is the rate limiting step in case of poorly soluble drugs in process of drug absorption. Poorly soluble drugs are presented with problems of variable bioavailability. Many techniques have been exercised to improve oral bioavailability of drugs. Among several methods, solid dispersion has attracted attention of the researchers for previous 50 years. Solid dispersions improve solubility of drug particles thus enhancing dissolution characteristics of drugs they increase the oral bioavailability. This review will focus on different aspects of solid dispersion preparation; their advantages, major challenges and preparation methods. Various solubility enhancers like water soluble carriers, cosolvents, surfactants and super disintegrates have been examined to aid in solubility enhancement. These significantly help to improve the bioavailability.