Stability of bioactive substances in formulations: degradation kinetics and key factors

Abstract

Stability of bioactive substances in formulations is discussed as a coupled chemical–physical problem that governs assay, impurity profile and performance over shelf‑life. Major degradation routes (hydrolysis, oxidation, isomerization/racemization and photolysis) are outlined together with microenvironmental drivers such as moisture/water activity, micro‑pH, trace metals, oxygen/light exposure, API-excipient compatibility and packaging barriers. Kinetic treatment (zero/first order, Arrhenius‑type approaches) and the limits of extrapolation in solid dosage forms are highlighted. Practical stabilization strategies are summarized, including moisture/oxygen control, antioxidants and chelators, management of amorphous states, and barrier packaging selection.