ABSTRACT
The preferred method for the administration of most drugs is via the oral route as conventional compressed tablet or dry-filled capsule formulations. However, there are a growing number of drugs and candidate drug compounds whose inherent solubility and permeability characteristics result in unacceptably low bioavailability when delivered from conventional oral formulations. Many times, standard manipulations aimed at enhancing bioavailability through improvements in the drug solubility or dissolution rate, such as particle size-reduction, or salt or crystal form selection, are either ineffective or do not enhance absorption sufficiently to make these traditional approaches viable options. In such instances, lipid-based formulations may offer an opportunity to enhance bioavailability through processes that impact physicochemical, and occasionally physiologic, mechanisms controlling drug absorption. Efforts to develop tablet formulations containing sufficient quantities of lipid and surfactant excipients to solubilize a poorly water-soluble drug have met with limited success due to the tendency for these excipients to compromise the physical integrity
and mechanical strength of conventional compressed tablets. However, most lipid-based formulations are compatible with either hard gelatin capsule (HGC) or soft gelatin capsule (SGC) shells, which allow the development of commercially viable oral dosage forms. The dynamic nature of fully or partially-solubilized drugs in lipid formulations, however, requires careful control of manufacturing, packaging, and handling conditions to maintain the physical and chemical stability of drug and excipients alike, thereby ensuring consistent product performance.
