A review of potential harmful interactions between anticoagulant/antiplatelet agents and Chinese herbal medicines

Abstract

Background: The risks attributed to drug-herb interactions, even when known, are often ignored or underestimated, especially for those involving anti-clotting drugs and Chinese medicines. The aim of this study was to structurally search and evaluate the existing evidence-based data associated with potential drug interactions between anticoagulant/antiplatelet drugs and Chinese herbal medicines (CHMs) and evaluate the documented mechanisms, consequences, and/or severity of interactions.

Methodology and findings: Information related to anticoagulant/antiplatelet drug-CHM interactions was retrieved from eight interaction-based textbooks, four web resources and available primary biomedical literature. The primary literature searches were conducted in English and/or Chinese from January 2000 through December 2011 using the secondary databases (e.g., PubMed, Airiti Library, China Journal full-text database). The search terms included the corresponding medical subject headings and key words. Herbs or natural products not used as a single entity CHM or in Chinese Medicinal Prescriptions were excluded from further review. The corresponding mechanisms and severity ratings of interactions were retrieved using MicroMedex®, Lexicomp® and Natural Medicines Comprehensive Database®. Finally, we found 90 single entity CHMs contributed to 306 documented drug-CHM interactions. A total of 194 (63.4%) interactions were verified for its evidence describing possible mechanisms and severity. Of them, 155 interactions (79.9%) were attributable to pharmacodynamic interactions, and almost all were rated as moderate to severe interactions. The major consequences of these interactions were increased bleeding risks due to the additive anticoagulant or antiplatelet effects of the CHMs, specifically danshen, dong quai, ginger, ginkgo, licorice, and turmeric.

Conclusions/significance: Conventional anticoagulants and antiplatelet drugs were documented to have harmful interactions with some commonly used single entity CHMs. For those patients who are taking conventional anti-clotting medications with CHMs for cardiovascular or cerebrovascular diseases, the potential risks of increased bleeding due to drug-CHM interactions should not be ignored.

Figure 1. Flow chart of primary literature search.

TPLS: Taiwan Periodical Literature System; CJFT: China Journals Full-text.

Figure 2. Retrieved findings of interactions between anticoagulant/antiplatelet agents and single Chinese herbal medicines.

* Natural products or herbs which were not identified in the Taiwan Herbal Pharmacopoeia, Chinese Medicinal Herbs Preparation, or Chinese Materia Medica were excluded. CHMs: Chinese herbal medicines.

Figure 3. Documented severity ratings of interactions between distinct anticoagulant/antiplatelet agents and single Chinese herbal medicines.

The total interactions between distinct anticoagulant/antiplatelet agents and single CHMs were 306. The classification of “No interaction” meant that there is no interaction between the medication and the single CHMs, while “No item” meant that there was no available information about the single CHMs in the database. NMCD: Natural Medicines Comprehensive Database.