INDIVIDUAL VARIABILITY IN DRUG METABOLISM BY CARBON DIOXIDE BREATH TESTS

初步测试的预测，咖啡因，低提取 定量药物（0.1）应是一个更敏感的酶诱导探针 比美沙西丁，一个高提取率药物（0.9），当排泄时， 代谢物（CO2）的测定已经进行。每种药物单次给药 对8名健康志愿者和9名癫痫患者进行了治疗 与苯妥英、卡马西平和/或苯巴比妥联用。13 C二氧化碳 用同位素比值质谱法测定呼气中的放射性同位素。的 比较了2小时内以CO2形式排泄的剂量百分比：3.22% + 0.86对照组和患者的咖啡因排泄量为5.54% ± 1.59， 分别为28.6% ± 5.8和40.0% ± 4.2。的 两个受试者组的结果均存在显著差异， 探针（p<.05）。这些数据不支持理论预测， 药物的提取率对其在以下方面的有用性具有关键影响： 通过二氧化碳检测氧化代谢的诱导 呼吸测试此外，初步数据显示， 本试验用于跟踪药物变化的时间过程的有用性 酒精中毒患者停止饮酒时的代谢/肝功能。

preliminary testing of the prediction that caffeine, a low extraction ration drug (0.1) should be a more sensitive probe of enzyme inducttion than methacetin, a high extraction ration drug (0.9), when excretion of a metabolite (C02) is measured has been carried out. A single dose of each was administered to 8 healthy volunteers and 9 epilepsy patients treated with phenytoin, carbarazepine and/or phenobarbital. The 13C carbon dioxide in expired breath was measured y isotope ratio mass spectrometry. The percentages of the dose excreted as CO2 in 2 hr. were compared: 3.22% + 0.86 and 5.54% + 1.59 caffeine was excreted by controls and patients, respectively, compared with 28.6% + 5.8 and 40.0% + 4.2 methacetin. The results in the 2 subject groups were significantly different for both probes (p<.05). These data do not support the theoretical prediction that the extraction ratio of a drug has a critical effect upon its usefulness in detection of induction of oxidative metabolism via the carbon dioxide breath test. In addition, preliminary data illustrate the potential usefulness of this test to follow the time course of changes in drug metabolism/liver function of an alcoholic patient when he stops drinking.