ABSTRACT
A high percentage of available drugs are administered orally through tablet or capsule dosage forms. This route is much more complex, compared to other routes, because of physiological conditions and other challenges the drug molecules encounter at the site of administration prior to reaching the general circulation and eliciting the pharmacological and/or therapeutic response. Therefore, developing formulations that produce consistent and desirable bioavailability, particularly for problematic drugs, presents many challenges. This chapter discusses the drug dissolution process and its importance in bioavailability and how various physicochemical properties of therapeutics agents and their processing play a critical role in influencing the drug dissolution and, therefore, bioavailability. Additionally, the chapter presents information on parameters that are used to assess bioavailability, and how to compute these parameters to assess the bioavailability of a drug. The chapter ends with a discussion on the importance of in vitro–in vivo correlations, various levels of correlations, and applicability and suitability of each level in formulation evaluations. The chapter also introduces readers to the Biopharmaceutical Classification System and its practical utility in anticipating potential bioavailability problems while developing formulations, granulating, and further processing of chemical entities.
