Injectable Formulations of Poorly Water-Soluble Drugs

Abstract

A growing number of new therapeutic molecules are limited by low or erratic bioavailability due to poor water solubility. Because of the clinical demand for new and more efficacious anti-cancer, antiviral, and anti-infective drugs, many of these new drugs must be formulated for injection. Poor water solubility can be addressed by a range of formulation approaches such as pH manipulation, salt formation, and cosolvent and surfactant addition, or by more advanced techniques such as complexation, liposomal encapsulation, or nanosuspension. While remaining focused on drug solubility, issues such as buffering, tonicity, sterility, and drug ­product stability also must be considered when formulating injectable products. This chapter outlines a formulator’s approach toward development of an injectable drug product containing an active ingredient with poor solubility. Marketed injectable products, listings of GRAS excipients, and techniques for enhancing solubility are offered as case studies to assist in the formulation process.