Dissolution enhancement of drugs. part i: technologies and effect of carriers

For complete absorption and good bioavailability of orally administered drug, the drug must be dissolved in gastric fluids. Dissolution of drug is the rate-controlling step which determines the rate and degree of absorption. Drugs with slow dissolution rates generally show erratic and incomplete absorption leading to low bioavailability when administered orally. Since aqueous solubility and slow dissolution rate of BCS class II and class IV drugs is a major challenge in the drug development and delivery processes, improving aqueous solubility and slow dissolution of BCS Class II and Class IV drugs have been investigated extensively. Various techniques have been used in attempt to improve solubility and dissolution rates of poorly water soluble drugs which include solid dispersion, micronization, lipid based formulations, melt granulation, direct compaction, solvent evaporation, coprecipitation, adsorption, ordered mixing, liquisolid compacts, solvent deposition inclusion complexation and steam aided granulation. In these techniques carrier plays an important role in improving solubility and dissolution rate. Polymers, superdisintegrants, surfactants are extensively studied in recent years for dissolution enhancement in drugs. This part of this review discusses technological overview and effect of polymers, superdisintegrants and surfactants on dissolution enhancement of drugs while Part II [Int J Health Res, Sept 2009; 2(3)] describes the role and applications of cyclodextrins, carbohydrates, hydrotropes, polyglocolized glycerides, dendrimers, acids and miscellaneous carriers in enhancing dissolution of drugs. Keywords: Dissolution enhancement; aqueous solubility, water soluble carriers; BCS class II, excipients.