Poorly water-soluble drugs and formulation strategy to improve oral bioavailability

Abstract

Poor water solubility of a drug is a tough and difficult task for researchers and pharmaceutical scientists during the formulation and development of dosage forms. Poor drug solubility often leads to inadequate and variable bioavailability. The properties of drugs cause problems in drug dissolution and its rates are solubility, particle size, polymorphism, salt form, complexation, wettability, etc. The improvement of drug solubility there by its oral bioavailability remains one of most challenging aspects of drug formulation process mostly for oral drug administration and the oral bioavailability will be governed by various parameters including dissolution rate, aqueous solubility, drug permeability, pre-systemic metabolism and susceptibility. To improve solubility and rate of dissolution, there are many approaches available like pH adjustment, particle size reduction, sono-crystallization, inclusion complexation, liquid solid methods, solid dispersion methods, self-emulsifying method, supercritical fluid processes, freeze drying method, spray drying method, hot melt extrusion method etc. Selection of right technique is the key to improve the drug dissolution and bioavailability and it helps to avoid the rejection of recent chemical entities because of low solubility.