Strom J G, Jun H W
J Pharm Sci. 1980 Nov;69(11):1261-3. doi: 10.1002/jps.2600691107.
The kinetics of degradation of methenamine were studied in citrate--phosphate buffers between pH 2.0 and 7.4 at 37.5 degrees. GLC was used to monitor the rate of hydrolysis. The conversion of methenamine to formaldehyde was found to be pH dependent in the buffers of constant ionic strength, with the reaction half-life decreasing from 13.8 hr at pH 5.8 to 1.6 hr at pH 2.0. The kinetics of degradation also were measured at 47, 57, and 67 degrees, and the reaction obeyed the Arrhenius relationship. At pH 2.0, the activation energy was calculated to be 23.5 kcal/mole; at pH 5.1, it was 12.0 kcal/mole.
在37.5摄氏度下，于pH值为2.0至7.4的柠檬酸盐 - 磷酸盐缓冲液中研究了乌洛托品的降解动力学。采用气相色谱法监测水解速率。发现在离子强度恒定的缓冲液中，乌洛托品向甲醛的转化取决于pH值，反应半衰期从pH 5.8时的13.8小时降至pH 2.0时的1.6小时。还在47、57和67摄氏度下测量了降解动力学，该反应符合阿仑尼乌斯关系。在pH 2.0时，计算出的活化能为23.5千卡/摩尔；在pH 5.1时，为12.0千卡/摩尔。
