Doctors of Chinese Medicine (DOMs) may prescribe herbs with caution, if at all, to those taking coumadin (warfarin). Why is this so? Because the administration of coumadin is not to be taken lightly. Coumadin is a coumarin-derived anticoagulant, and specifically a Vitamin K Antagonists (VKA). Potentiation of its anticoagulant effect could cause bleeding and hemorrhage. While inhibition could precipitate blood clots and emboli.
Standards of care for the prescribing of coumadin come from the American College of Clinical Pharmacy, and the American Heart Association/American College of Cardiology (Epocrates Online).
Coumadin is prescribed for the prevention of deep vein thromboembolism (DVT); prevention of embolism in patients with atrial fibrillation and prosthetic heart valves; and reduction of the risk of recurrent MI [and stroke] (James, 2009). The risk vs. benefit of managing these conditions via means other than pharmacology (e.g. diet & lifestyle, Chinese herbs, and supplements etc.) is high if they can not achieve the same therapeutic efficacy as coumadin in preventing morbidity & mortality from these conditions.
There are some situations were the administration of coumadin is contraindicated. Patient are primarily assessed for blood dyscrasias - a tendency for bleeding, and ability to comply with the drug dosing and follow-up regimens. After administration commences, the patient is monitored for (a) serious reactions that may require medical attention (hemorrhage anywhere in the body, tissue necrosis/ gangrene, cholesterol embolism etc.), and anaphylaxis, (b) reactions that may cause noncompliance (abdominal cramps, pain, distention, flatulence; nausea, vomiting, diarrhea; fatigue, malaise, headache etc), and (c) reactons that may go unassociated with coumadin (pruritus, rash, urticaria, and alopecia).
Patient education begins with the signs of bleeding such as bleeding gums, bruises, petechiae, nosebleeds, tarry stoos, and rosy-colored urine from over anticoagulation with coumadin (especially with initial dose & high dose). Second, is to educate the patient that the combinations of coumadin with some foods, OTC drugs, herbs & supplements may alter its efficacy (potentiate or inhibit). Patients should consult with a provider, and take coumadin as prescribed the same time daily.
Coumadin intercepts with the extrinsic vitamin-K dependent clotting factors in the liver (Edmunds & Mayhew, 2013). Its anticoagulant properties may be influenced by vitamin K production by GI flora, as well as foods that are rich in vitamin K. Patients are instructed to be consistent with the consumption of these foods to avoid wide fluctuations in INR. The patient can expect a baseline CBC, platelet, hemoglobin & hematocrit (HCT & HBG), and PT/PTT/INR. Then s/he must comply with lab monitoring of PT/INR every week for the first month, then every other week, and then once per month. The therapeutic INR is between 2-3. HCT is monitored for occult bleeding.
Coumadin has a narrow therapeutic range, and is highly plasma protein-bound. It is metabolized by the liver, and is a substrate of many cytochrome pathways and sub-pathways. Due to these factors, there exists a very high likelihood that the anticoagulant effect of coumadin is influenced by other drugs, foods, herbs & supplements that enhance or inhibit the cytochrome P450 pathways, and plasma albumin levels.
According to Galland (2008), many case studies warn of potential interactions between coumadin and herbs & supplements, with few actually validated by controlled studies. DOMs should be aware of Chinese herbs & supplements that may interact with coumadin based solely upon case study: fenurgeek (hu Lu ba), garlic (da suan), chlorella (contains vitamin K) , Chinese angelica root (dang gui), salvia miltiorrhizae (dan shen), red yeast rice (lovistantin), CoQ10, vitamin E, vitamin C, and fish oil etc. Verses those that definitivley interact with coumadin: vitamin K and St. John's Wort (tian ji huang or guan ye jin si tao).
Herbs & supplements that enhance or prolongs coumadin's anticoagulant effect (increase above therapeutic INR), may precipitate bleeding or hemorrhage. These include ginko baloba (bai guo), and panax ginseng (ren shen), and green tea. Herbs & supplements that inhibit coumadin's anticoagulant effect (decrease from therapeutic INR), may increase the risk for deep venous thrombi, emboli and stoke. St. John's Wort (SJW) definitively and significantly decreases INR and plasma coumadin level (Galland, 2008).
Integrative Medicine Tip: Tian ji huang or guan ye jin si tao, is used in Chinese herbal medicine for plateaus occurring at the beginning of
treatment for depression with traditional Chinese herbs- with 6 to 8 weeks to see benefit. Mischoulon & Rosenbaum (2008) cite that supplementation with 800 mg of SJW taken once per day is shown to be as effective as an SSRI for mild depression. The same precautions taken with SSRIs, also appy to SJW. In order to prevent SSRI syndrome, wait 2 wks after discontinuing an SSRI (e,g, Lexpro) before starting SJW (Mischoulon & Rosenbaum, 2008) . SJW induces the cytochrome P450 system in the liver. Thus, care must be taken with co-administration of contraceptives, antibiotics, and cardiovascular medications etc. An oil-infusion of SJW is used to soothe nerve pain, not for depression; thus, the same precautions may not apply.
Dr. John Chen Pharm.D., is a practitioner of Oriental Medicine, and coauthor of a Chinese herb & formula pharmacopeia used in the US. He is an expert & accessible consultant to healthcare professionals regarding the dynamics between pharmaceutical drugs and Chinese herbs. His online lectures on the topic are excellent resource for Doctors of Oriental Medicine.
Edmunds, M., & and Mayhew, M. (2013). Pharmacology for the primary care provider (4th ed).
St. Louis, MO: Elsevier Mosby.
Epocrates Online. Coumadin. Retrieved from https://online.epocrates.com.
Galland, L. (2008). Drug supplement interactions: The good, the bad and the undetermined. In
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James, S. (2009). Hematology pharmacology: Anticoagulant, antiplatelet, and procoagulant
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Mischoulon, D. & Rosenbaum, J. (2008). Natural medications for psychiatric disorders:
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