Updates on the Clinical Evidenced Herb‐Warfarin Interactions

Abstract

Increasing and inadvertent use of herbs makes herb-drug interactions a focus of research. Concomitant use of warfarin, a highly efficacious oral anticoagulant, and herbs causes major safety concerns due to the narrow therapeutic window of warfarin. This paper presents an update overview of clinical findings regarding herb-warfarin interaction, highlighting clinical outcomes, severity of documented interactions, and quality of clinical evidence. Among thirty-eight herbs, Cannabis, Chamomile, Cranberry, Garlic, Ginkgo, Grapefruit, Lycium, Red clover, and St. John's wort were evaluated to have major severity interaction with warfarin. Herbs were also classified on account of the likelihood of their supporting evidences for interaction. Four herbs were considered as highly probable to interact with warfarin (level I), three were estimated as probable (level II), and ten and twenty-one were possible (level III) and doubtful (level IV), respectively. The general mechanism of herb-warfarin interaction almost remains unknown, yet several pharmacokinetic and pharmacodynamic factors were estimated to influence the effectiveness of warfarin. Based on limited literature and information reported, we identified corresponding mechanisms of interactions for a small amount of “interacting herbs.” In summary, herb-warfarin interaction, especially the clinical effects of herbs on warfarin therapy should be further investigated through multicenter studies with larger sample sizes.

Analysis of the first therapeutic-target-achieving time of warfarin therapy and associated factors in patients with pulmonary embolism

“…In the present study, the active ingredients of the blood circulation-activating drugs were predominantly ginkgo, angelica and salvia (63), which were demonstrated to reduce the clearance rate of warfarin and enhance its anticoagulant effect, resulting in increased INR values. These active ingredients also inhibited platelet aggregation and increased blood clotting enzyme factor III and fibrinolytic activity.…”

Anticoagulant effects of phytotherapeutic drugs and their importance in surgical dental procedures

“…Its antiplatelet action has already been reported [1][2][3][4][5] , although there are controversies on this matter 22 . The anticoagulant effects of Ginkgo biloba have been reported mainly when this substance is used in combination with allopathic drugs, such as warfarin 5 , heparin 18 , aspirin 1,11,19,23 , and ibuprofen 24 . Therefore, dentists must be attentive to patients taking Ginkgo biloba, particularly when this substance is associated with other drugs of high hemorrhagic potential, before performing surgical procedures.…”

“…Therefore, it is recommended that Allium sativum be suspended at least one week before a surgical dental procedure 10 . In case of combined used with warfarin, this recommendation is even more important, because of the likelihood of high interaction 5,10 .…”

“…Alternative substances for treating or preventing several diseases have aroused the interest of the population around the world, including natural substances and phytotherapeutic drugs [1][2][3][4][5] . Phytotherapeutic drugs are plant-derived products with medicinal properties.…”

“…Nonetheless, considering the many countries where they are produced and marketed 8 , it could be reasonably assumed that the general population may use them without a medical or dental prescription, as an adjuvant in capillary treatment, and for the treatment of varicose veins and hemorrhoids [18][19] . It interferes with platelet function and with the coagulation action of warfarin 5,21 and other drugs 18 . Therefore, its use must be avoided before surgical dental procedures.…”