Buccal Absorption of Biopharmaceutics Classification System III Drugs: Formulation Approaches and Mechanistic Insights

Buccal drug delivery emerges as a promising strategy to enhance the absorption of drugs classified under the Biopharmaceutics Classification System (BCS) Class III, characterized by high solubility and low permeability. However, addressing the absorption challenges of BCS Class III drugs necessitates innovative formulation strategies. This review delves into optimizing buccal drug delivery for BCS III drugs, focusing on various formulation approaches to improve absorption. Strategies such as permeation enhancers, mucoadhesive polymers, pH modifiers, ion pairing, and prodrugs are systematically explored for their potential to overcome challenges associated with BCS Class III drugs. The mechanistic insight into how these strategies influence drug absorption is discussed, providing a detailed understanding of their applicability. Furthermore, the review advocates for integrating conventional buccal dosage forms with these formulation approaches as a potential strategy to enhance absorption. By emphasizing bioavailability enhancement, this review contributes to a holistic understanding of optimizing buccal absorption for BCS Class III drugs, presenting a unified approach to overcome inherent limitations in their delivery.