Biopharmaceutics. Biopharmaceutics is a major branch in pharmaceutical sciences that relates between the physicochemical properties of a drug in dosage form and the pharmacology, toxicology, or clinical response observed after its administration. Drug efficacy and safety are dependent on the dosing regimen. Biopharmaceutics and pharmacokinetics are pharmaceutical disciplines useful to improve the outcome of drug therapies, assist drug product development, and establish pharmacokinetics-pharmacodynamics models and in vitro-in vivo correlations.