Drug dissolution: significance of physicochemical properties and physiological conditions.

Oral bioavailability of a drug is determined by a number of properties, including drug dissolution rate, solubility, intestinal permeability and pre-systemic metabolism. Frequently, the rate limiting step in drug absorption from the gastrointestinal tract is drug release and drug dissolution from the dosage form. Therapeutic agents with aqueous solubilities less than 100μg/ml often present dissolution limitations to absorption. Physicochemical, formulation-related and physiological factors can all influence drug dissolution. In this review, the authors will discuss the important physicochemical properties of a drug and physiological conditions in the gastrointestinal tract that play an important part in drug dissolution and absorption processes and, consequently, the bioavailability of a drug.