Abstract

Formulation design, in general, involves chemistry and engineering, thus requiring an understanding of the variety of excipient chemicals and manufacturing techniques. Drug molecules are often poorly water-soluble and are difficult to effectively administer in vivo owing to solubility limitations. Fortunately, there is a wide selection of solubilizing excipients that are generally regarded as safe that can be judicially used to safely and effectively administer drugs with a wide variety of physiochemical properties and chemical structure. Some old and well-established solubilizing excipients such as pH modifiers, organic solvents, and surfactants are widely used and can meet many formulation needs. Some solubilizing excipients that have been known for a while are finally receiving well-deserved attention with commercial successes such as α-tocopherols and oleic acid. Future prospects will include advances in scientific understanding of the interactions between drugs and excipients with endogenous in vivo fluids and physiological processes, technological innovations in new manufacturing techniques such as nanotechnology, and improvements in existing methods such as solid dispersions, as well as new excipients. This article focuses on solubilizing excipients with selected examples of commercially available human pharmaceutical products, and is organized by route of administration—oral, injectable, and transdermal.