Somogyi A, Rohner H G, Gugler R
Clin Pharmacokinet. 1980 Jan-Feb;5(1):84-94. doi: 10.2165/00003088-198005010-00003.
The pharmacokinetics and bioavailability of cimetidine after 200 mg given intravenously and orally was studied in 6 gastric and 6 duodenal ulcer patients aged between 28 and 64 years. There were no differences in any of the pharmacokinetic parameters between the two ulcer groups, but there was considerable variation which was mainly age-related. Bioavailability was not complete, but was about 60% based on the plasma concentration data. The volume of distribution at steady-state was about 80% of body weight, and the plasma clearance value of 495 ml/min was mainly due to renal clearance (293 ml/min). The elimination half-life was approximately 2 hours. These pharmacokinetic parameters together with the percentage of dose excreted unchanged in urine following intravenous administration were all highly age correlated; all decreasing with age except the elimination half-life which increased with age. Of clinical importance is the finding that the time for which the plasma concentration exceeded 0.5 microgram/ml following oral administration was also highly age-dependent, increasing by more than 2-fold in the elderly (53 to 64y) compared with the younger (28 to 45y) patients.
在6名年龄在28至64岁之间的胃溃疡患者和6名十二指肠溃疡患者中，研究了静脉注射和口服200毫克西咪替丁后的药代动力学和生物利用度。两个溃疡组之间的任何药代动力学参数均无差异，但存在相当大的变异性，主要与年龄相关。生物利用度不完全，但根据血浆浓度数据约为60%。稳态分布容积约为体重的80%，血浆清除率值495毫升/分钟主要归因于肾清除率（293毫升/分钟）。消除半衰期约为2小时。这些药代动力学参数以及静脉给药后尿液中以原形排泄的剂量百分比均与年龄高度相关；除消除半衰期随年龄增加外，所有参数均随年龄降低。具有临床重要性的发现是，口服给药后血浆浓度超过0.5微克/毫升的时间也高度依赖于年龄，与年轻患者（28至45岁）相比，老年患者（53至64岁）增加了2倍以上。
