. Can. J. Chem. 68, 21 11 (1990). The shelf-or use-life of a material which decomposes by an autocatalytic reaction is shown to be inversely proportional to the rate of heat generation during the induction period of the degradation reaction. Calorimetric measurement of the rate of heat generation during the induction period takes only a few hours. It can often be done at or very near the actual storage or use temperature of the material. Measurements on Lovastatin (2-methylbutanoic acid 1 ,2,3,7,8,8a-hexahydro-3,7-dimethyl-8-[2-(tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl)ethyl]-l-naphthalenylester) are used as an example of this application. On dkmontre que la pCriode de pCriode de pCremption d'un produit qui se decompose par un mkcanisme autocatylique est inversement proportionnelle au taux de rkchauffement du produit au cours de la pCriode d'induction de la rCaction de dCgradation. Les mesures calorimCtriques de ce taux de richauffement au cours de la pCriode d'induction ne demandent que quelques heures et ils peuvent souvent Ctre diterminCs dans ou prks du lieu d'entreposage; ou on peut utiliser la temgrature du produit. Comme exemple d'application de la mCthode, on prisente des donnCes relatives au Lovastatin (2-mCthylbutanoate du 1, 2, 3, 7, 8, 8a-hydro-3,7-dimCthyl-8-[2-(tCtrahydro-4-hydroxy-6-0~0-2H-pyran-2-yl)Cthyl]-l-naphta1Cnyle).

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The application of heat conduction calorimetry to the determination of decomposition mechanisms and rates for drugs is shown to be a rapid and generally useful method. The application of the method to determine the nature of the decomposition reaction, sources of systematic errors in the method, the equations relating the calorimetric signal to the kinetics of the reaction, and some examples of results are presented and discussed.

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