Powell M F
J Pharm Sci. 1986 Sep;75(9):901-3. doi: 10.1002/jps.2600750917.
In the absence of strong buffer catalysts, the degradation of codeine sulfate (7,8-didehydro-4,5 alpha-epoxy-3-methoxy-17-methylmorphinan-6 alpha-ol sulfate) in aqueous solution is described by the expression kobs = kH+ [H+] + k0 + kHO-[HO-], where kH+ = (3.9 +/- 1.3) X 10(-8) M-1 X S-1, k0 = (2.7 +/- 0.5) X 10(-8) S-1, and kHO- = (5.1 +/- 1.0) X 10(-6) M-1 X S-1 at 80 degrees C. The activation energies associated with these rate constants are 27.7, 21.0, and 28.3 kcal X mol-1, respectively. In the absence of buffer catalysis, codeine sulfate is predicted to have a room temperature shelf life of approximately 44 years between pH 1 and 10, significantly longer than the 1.1 year shelf life of codeine phosphate reported earlier.
在没有强缓冲催化剂的情况下，硫酸可待因（7,8 - 二脱氢 - 4,5α - 环氧 - 3 - 甲氧基 - 17 - 甲基吗啡喃 - 6α - 醇硫酸盐）在水溶液中的降解可用表达式kobs = kH+ [H+] + k0 + kHO-[HO-]来描述，其中在80℃时，kH+ = (3.9 ± 1.3) × 10(-8) M-1 × s-1，k0 = (2.7 ± 0.5) × 10(-8) s-1，kHO- = (5.1 ± 1.0) × 10(-6) M-1 × s-1。与这些速率常数相关的活化能分别为27.7、21.0和28.3千卡×摩尔-1。在没有缓冲催化的情况下，预计硫酸可待因在pH值1至10之间的室温保质期约为44年，明显长于先前报道的磷酸可待因1.1年的保质期。
