ABSTRACT
A majority of the chiral excipients employed in pharmaceutical dosage forms are from natural sources and therefore exist in the optically pure form. Chiral excipients have been traditionally used, though unintentionally, in many pharmaceutical dosage forms [1-3] and as stationary phases for gas and liquid chromatography in qualitative and/or quantitative analysis of enantiomeric drugs [4-7]. In the latter case, the interaction between chiral excipients and drugs forms the basis for the separation of enantiomers. Many advances have been made in the use of chiral polymeric materials as stationary phases in liquid and gas chromatography, and in capillary electrophoresis. Fortuitously, some of the investigations that have been documented regarding chiral excipients in pharmaceutical formulations are based on the knowledge of chiral stationary phases. With the advent of stereospecific analytical methods in recent years, more attention has be drawn to the influence of chiral excipients on the modification of in vitro release and in vivo disposition of chiral drugs [1,2,8,9]. However, the significance of drug delivery modulation as a result of chiral drug-excipient interactions has been controversial [13,10]. This article presents a concise review on the use of selected chiral excipients in pharmaceutical dosage forms containing chiral therapeutic agents.
