Evaluation of heat-conduction microcalorimetry in pharmaceutical stability studies. I. Precision and accuracy for static experiments in glass vials.

inTroDuCTion In the preformulation stage of pharmaceuticals, accelerated stability studies using data from DSC/DTA studies, combined with analytical techniques such as spectroscopy and HPLC are the normal methods used to collect data. The possibility to use isothermal heat conduction microcalorimetry to obtain rate constants at close to, or at room temperatures could therefore be of interest for reactions that follow the Arrhenius relationship. The objective was to evaluate the precision and accuracy of the microcalorimetric system by measuring the rate constant at several temperatures and calculating the activation energy of the well documented hydrolysis of acetylsalicylic acid (ASA) in aqueous solution of pH 1.1.