2014 年 40 巻 4 号 p. 230-236
A previous study examined the stability of anti-HIV agents prepared according to a simple suspension method. The results indicated a significant decline in the percentage of tenofovir disoproxil fumarate (TDF) remaining when suspended and kept in a warm bath at 80 °C for 60 min. The study identified a probable decomposition product and examined the effects of the temperature and duration of suspension. The present study determined changes in the amount of TDF remaining over time when the drug was suspended at temperatures of 70 - 90 °C and kept in a warm water bath. In the thermal decomposition of TDF, the reaction rate increased as the storage temperature rose, and the remaining product was decreased following the first-order reaction. And the activation energy (Ea) was calculated as 78.6 kJ・mol-1 from an Arrhenius plot. The percentage of drug remaining reached 98％ in 58.7 min at 55 °C. And the decomposition product, which was identified as tenofovir monoester, is the hydrolysis product of TDF. Such detailed data on the thermal stability of the TDF was considered to be useful basic data when examining the feasibility of a simple suspension method.