A Novel Prodrug of Salicylic Acid, Salicylic Acid-Glutamic Acid Conjugate Utilizing Hydrolysis in Rabbit Intestinal Microorganisms.
作者:Junzo NAKAMURA、Kumiko ASAI、Koyo NISHIDA、Hitoshi SASAKI
DOI:10.1248/cpb.40.2164
日期:——
The fate of salicylic acid-glutamic acid conjugate (salicyl-glutamic acid) following oral, intravenous, intracecal and rectal administration (60, 10, 5 and 5 mg/kg, respectively : salicylic acid equivalent) was examined in rabbits. Salicylic acid was detected in the blood 2 h after oral administration of salicyl-glutamic acid and it reached the maximum level (69.4 μg/ml) at 18 h after the dose. A high blood concentration of salicylic acid (24.8 μg/ml) was observed up to 36 h. But only a small amount of salicyl-glutamic acid was detected in the blood (<2.5 μg/ml, as salicylic acid). In contrast, unchanged salicyl-glutamic acid was found mainly in the blood following intravenous administration of salicyl-glutamic acid, suggesting that presystemic de-conjugation of salicyl-glutamic acid predominantly occurred. The intestinal mucosal de-conjugation of salicyl-glutamic acid was negligible in the in situ intestinal sac preparation with complete mesenteric venous blood collection. Immediate and very extensive salicylic acid formation in the cecum was found following intracecal administration of salicyl-glutamic acid. After oral pretreatment of rabbits with kanamycin sulfate (6 × 400 mg), a significant inhibition of salicylic acid formation following intracecal administration of salicyl-glutamic acid was observed, indicating that the intestinal microorganisms were responsible for the biotransformation of salicyl-glutamic acid. Also, in vitro incubation of salicyl-glutamic acid with gut contents showed that the primary location of hydrolysis was the hind gut.
口服、静脉注射、盲肠内和直肠内给药(分别为60、10、5和5 mg/kg:水杨酸等效剂量)后,在兔体内研究了水杨酸-谷氨酸共轭物(水杨酸谷氨酸)的命运。口服水杨酸谷氨酸后2小时,血液中检测到水杨酸,给药后18小时达到最大水平(69.4 μg/ml),高达36小时血液中水杨酸浓度保持较高水平(24.8 μg/ml)。但仅检测到少量水杨酸谷氨酸(<2.5 μg/ml,以水杨酸计)。相比之下,水杨酸谷氨酸静脉注射后,主要在血液中发现了未改变的水杨酸谷氨酸,表明水杨酸谷氨酸的系统前脱共轭作用主要发生。在完全门静脉血液收集的原位肠道囊制备中,水杨酸谷氨酸的肠道黏膜脱共轭作用可以忽略不计。水杨酸谷氨酸盲肠内给药后,盲肠中立即形成大量水杨酸。在静脉给予硫酸卡那霉素(6 x 400 mg)预处理兔后,盲肠内给予水杨酸谷氨酸发现水杨酸形成明显受抑制,表明肠道微生物负责水杨酸谷氨酸的生物转化。此外,水杨酸谷氨酸与肠道内容物体外孵育显示,水解的主要部位在远端肠道。