Pharmaceutical microcalorimetry: applications to long-term stability studies

Calorimetry has been a mainstay of stability analyses for some time in the form of differential scanning microcalorimetry (DSC). This technique exploi ts high (relatively) temperature studies of pure materials and of formulati ons to accelerate any degradation or interactions. The behaviour of the mat erial at storage or ambient conditions is then estimated via extrapolation from the Arrhenius equation. Recent developments in isothermal microcalorim etry allow the direct determination of both kinetic and thermodynamic param eters for long, slow reactions from studies conducted at appropriate temper atures and under designated environmental control (pH, pO(2), RH etc.). Thi s review introduces the kinetic analysis of microcalorimetric data and, thr ough selected examples, shows applications of the method. (C) 1999 Elsevier Science B.V. All rights reserved.