ABSTRACT

This chapter focuses on absorption aspect and pharmacokinetic behaviors of water-insoluble drugs. It provides physiological and pathophysiological factors that could affect drug absorption. Orally administered drugs with pH-dependent solubility, especially weak bases, may demonstrate altered drug absorption in patients with various gastric pH. The food– drug interactions for water-insoluble drugs usually manifest themselves either in alteration in absorption rate or in absorption extent. Modeling and simulation approaches can help the formulation development and optimization for water-insoluble drugs. The chapter discusses the typical absorption, zero-order absorption, and erratic absorption. Gastric emptying-slowing agents, another class of gastrointestinal motility modifying agents, include opioids. Water-insoluble drugs usually have high propensity for drug interactions at absorption level, such as food interaction, interactions with gastrointestinal prokinetic agents, effect of alteration in gastric pH with concomitant use of gastric pH modulating agents, especially if these drugs also have narrow therapeutic windows.