Lam A Y, Elmer G W, Mohutsky M A
Department of Pharmacy, University of Washington, Seattle 98104-3031, USA.
Ann Pharmacother. 2001 Oct;35(10):1199-201. doi: 10.1345/aph.1Z442.
To describe a patient who was stabilized on warfarin and developed an elevated international normalized ratio (INR) after drinking a concentrated Chinese herbal tea. Additionally, to determine the effect of the tea on CYP2C9, the isoenzyme responsible for the metabolism of S-warfarin.
An elevated INR of 4.1 was observed in a 61-year-old Chinese woman, previously stabilized on anticoagulation therapy (INR 2-3). With no changes in her other medications or lifestyle, a review of her dietary habits revealed four days of drinking a concentrated Chinese herbal tea made from Lycium barbarum L. fruits (3-4 glasses daily) prior to her clinic visit Warfarin was withheld for one day and then resumed at a lower weekly dose. She discontinued the tea, while maintaining consistency with medications and dietary habits. A follow-up INR seven days later was 2.4, and seven subsequent INR values were in the 2.0-2.5 range.
L barbarum L. (family Solanaceae) is a commonly used Chinese herb considered to have a tonic effect on various organs. Any impact of an herbal product on the metabolism of S-warfarin, the enantiomer responsible for most of the anticoagulant activity, could alter the INR values. An herbal-drug interaction was suspected in this case. In vitro evaluation showed inhibition of S-warfarin metabolism by CYP2C9 by the tea of L. barbarum L.; however, the inhibition observed was weak, with a dissociation constant (Ki) value of 3.4 mg/mL, suggesting that the observed interaction may be caused by factors other than the CYP450 system.
There is a potential herbal-drug interaction between warfarin and L. barbarum L., based on an increased INRvalue noted with concurrent use. Thus, combination of L. barbarum L. and warfarin should be avoided. Vigilance is needed with other herbal combinations taken with drugs of narrow therapeutic indices.
描述一名服用华法林病情稳定，但在饮用浓缩的中国草药茶后国际标准化比值（INR）升高的患者。此外，确定该茶对负责S-华法林代谢的CYP2C9同工酶的影响。
一名61岁的中国女性，之前抗凝治疗病情稳定（INR为2 - 3），此次观察到INR升高至4.1。其其他药物和生活方式均无变化，询问饮食习惯发现，就诊前四天她每天饮用由枸杞制成的浓缩中国草药茶（每天3 - 4杯）。停用华法林一天，之后以较低的每周剂量恢复用药。她停止饮用该茶，同时保持用药和饮食习惯一致。七天后的随访INR为2.4，随后的七个INR值在2.0 - 2.5范围内。
枸杞（茄科）是一种常用的中国草药，被认为对各种器官有滋补作用。任何草药产品对S-华法林（负责大部分抗凝活性的对映体）代谢的影响都可能改变INR值。本病例怀疑存在草药 - 药物相互作用。体外评估显示枸杞茶可抑制CYP2C9对S-华法林的代谢；然而，观察到的抑制作用较弱，解离常数（Ki）值为3.4 mg/mL，这表明观察到的相互作用可能由CYP450系统以外的因素引起。
基于同时使用时INR值升高，华法林与枸杞之间存在潜在的草药 - 药物相互作用。因此，应避免枸杞与华法林联用。对于与治疗指数窄的药物同时服用的其他草药组合，需要保持警惕。
