文章基本信息

标题：Enhancement of the Oral Bioavailability of Phenytoin by N-Acetylation and Absorptive Characteristics
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作者：Taro OGISO ; Tadatoshi TANINO ; Dai KAWARATANI 等
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：1998
卷号：21
期号：10
页码：1084-1089
DOI：10.1248/bpb.21.1084
出版社：The Pharmaceutical Society of Japan
摘要：To improve the absorbability of phenytoin (DPH), a prodrug, N-acetyl-DPH (EDPH), was synthesized, and the absorptive characteristics and pharmacokinetics of the prodrug were evaluated in rats. EDPH was rapidly hydrolyzed to DPH in the intestinal fluid and the mucosa (rate constant, 0.055 and 0.169 min^-1, respectively). The plasma concentrations of DPH after intravenous dosing of EDPH declined in a biexponential manner, although two different elimination patterns were observed in these rats. When dosed orally (25 mg/kg, DPH equivalent), the plasma levels of DPH converted from the prodrug were significantly higher and more sustained than those after DPH alone, giving bioavailability 11.4 (rapid decay) and 9.1 times (slow decay) as high, respectively, as that after DPH alone. The concentrations of DPH distributed into the mucosa of the duodenum and jejunum 1 and 5 h after oral dosing of EDPH were significantly higher than those after DPH alone. The prodrug and DPH converted from the prodrug dissolved 2-4 fold more than DPH alone in bile salt solution and bile salt-oleic acid mixed micelles, indicating the increased solubility of the prodrug in the intestinal fluid. It is concluded from the data that such high solubility of EDPH enhanced the intestinal absorption of the prodrug, part of which would be absorbed in the amide form, and thus gave the high bioavailability.
关键词：N-acetylphenytoin;absorption;pharmacokinetics;intestinal distribution;solubility;hydrolysis