Collins D M, Gidal B E, Pitterle M E
University of Wisconsin Hospitals and Clinics, Madison.
Ann Pharmacother. 1993 Oct;27(10):1180-7. doi: 10.1177/106002809302701003.
To report a potential interaction between carbamazepine (CBZ), an anticonvulsant medication, and loxapine, an antipsychotic. CBZ is being increasingly used to treat a variety of psychiatric disorders. Because of this, the potential for multiple-drug therapy and subsequent drug interactions is increased.
We prospectively monitored plasma CBZ and carbamazepine epoxide (CBZE) concentrations in a single patient during and after withdrawal of loxapine comedication. Additionally, we retrospectively evaluated four patients who had received concomitant therapy with CBZ and loxapine.
Plasma CBZE/CBZ ratios decreased from 0.76 to 0.18 following discontinuation of loxapine. Absolute CBZE plasma concentrations also decreased from 1.7 to 0.6 micrograms/mL after loxapine therapy was stopped. Retrospectively screened patients who were receiving concomitant loxapine-CBZ therapy all had unusually elevated CBZE/CBZ plasma concentration ratios (0.75-1.91).
These cases suggest that an interaction occurs between loxapine and CBZ. Possible mechanisms include either induction of CBZ metabolism to its epoxide metabolite, or inhibition of the enzymatic metabolism of CBZE (epoxide hydrolase).
报告抗惊厥药物卡马西平（CBZ）与抗精神病药物洛沙平之间的潜在相互作用。CBZ越来越多地用于治疗多种精神疾病。因此，多药治疗及随后药物相互作用的可能性增加。
我们前瞻性监测了一名患者在停用洛沙平合并用药期间及之后的血浆CBZ和卡马西平环氧化物（CBZE）浓度。此外，我们回顾性评估了四名接受CBZ和洛沙平联合治疗的患者。
停用洛沙平后，血浆CBZE/CBZ比值从0.76降至0.18。洛沙平治疗停止后，CBZE血浆绝对浓度也从1.7微克/毫升降至0.6微克/毫升。回顾性筛查接受洛沙平-CBZ联合治疗的患者，其血浆CBZE/CBZ浓度比值均异常升高（0.75 - 1.91）。
这些病例表明洛沙平与CBZ之间存在相互作用。可能的机制包括诱导CBZ代谢为其环氧化物代谢物，或抑制CBZE（环氧化物水解酶）的酶促代谢。
