Warfarin
Warfarin (also known under the brand names Coumadin, Jantoven, Marevan, Lawarin, and Waran) is an anticoagulant. It was initially marketed as a pesticide against rats and mice and is still popular for this purpose, although more potent poisons such as brodifacoum have since been developed. A few years after its introduction, warfarin was found to be effective and relatively safe for preventing thrombosis and embolism (abnormal formation and migration of blood clots) in many disorders. It was approved for use as a medication in the early 1950s and has remained popular ever since; warfarin is the most widely prescribed anticoagulant drug in North America.
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.
Source : PlosOne
Link to Full Article
HERBS:
Bilberry (Vaccinium myrtillus)
High doses of bilberry - potentiation of bleeding possible. Antiplatelet activity have been observed with high doses of bilberry.
Check at high doses (low risk > 100 mg/day anthocyanins).
Dan Shen (Salvia miltiorrhiza)
May increase the effect of drug:
Case reported.
Contraindicated.
Devil’s Claw (Harpagophytum procumbens)
Purpura due possibly to increased bleeding tendency
(Purpura is purple-colored spots and patches that occur on the skin, organs, and in mucus membranes, including the lining of the mouth. When purpura spots are very small, they are called petechiae. Large purpura are called ecchymoses)
Check (very low level of risk).
Dong Quai (Angelica sinensis/Angelica polymorpha)
May increase the effect of drug:
Case reported.
Monitor (low level of risk
Garlic (Allium sativum)
May increase the effect of drug:
Large doses may increase bleeding tendency.
Case reports of possible interaction and increased bleeding tendency
Contraindicated for doses > 5 g/day garlic (fresh) unless under close supervision
Ginger (Zingiber officinales)
Increased risk of spontaneous bleeding.
High doses - 5 g/day -Inhibits platelet aggregation and thromboxane .
2 g/day - no effect
Check at doses < 4 g/day dried ginger.
> 4 g/day dried ginger - Contraindicated unless under close supervision
Korean Ginseng / Panax ginseng
May decrease effectiveness of drug:
One case reported
Check (low level of risk)
Meadowsweet (Filipendula ulmaria)
May increase effects of drug.
Theoretical concern based on animal studies (in vivo) which showed anticoagulant activity.
Check (low level of risk)
St John’s Wort (Hypericum perforatum)
Decreases drug levels
Cases reported
Contraindicated.
Willow Bark (Salix alba, Salix daphnoides, Salix purpurea, Salix fragilis)
May increase effects of drug.
A very mild but significant antiplatelet activity was observed in a Clinical study
Check (low level of risk)
A Review of Potential Harmful Interactions between Anticoagulant/Antiplatelet Agents and Chinese Herbal Medicines
- Hsin-Hui Tsai,
-
Hsiang-Wen Lin
mail,
- Ying-Hung Lu,
- Yi-Ling Chen,
- Gail B. Mahady
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.
Source : PlosOne
Link to Full Article
HERBS:
Bilberry (Vaccinium myrtillus)
High doses of bilberry - potentiation of bleeding possible. Antiplatelet activity have been observed with high doses of bilberry.
Check at high doses (low risk > 100 mg/day anthocyanins).
Dan Shen (Salvia miltiorrhiza)
May increase the effect of drug:
Case reported.
Contraindicated.
Devil’s Claw (Harpagophytum procumbens)
Purpura due possibly to increased bleeding tendency
(Purpura is purple-colored spots and patches that occur on the skin, organs, and in mucus membranes, including the lining of the mouth. When purpura spots are very small, they are called petechiae. Large purpura are called ecchymoses)
Check (very low level of risk).
Dong Quai (Angelica sinensis/Angelica polymorpha)
May increase the effect of drug:
Case reported.
Monitor (low level of risk
Garlic (Allium sativum)
May increase the effect of drug:
Large doses may increase bleeding tendency.
Case reports of possible interaction and increased bleeding tendency
Contraindicated for doses > 5 g/day garlic (fresh) unless under close supervision
Ginger (Zingiber officinales)
Increased risk of spontaneous bleeding.
High doses - 5 g/day -Inhibits platelet aggregation and thromboxane .
2 g/day - no effect
Check at doses < 4 g/day dried ginger.
> 4 g/day dried ginger - Contraindicated unless under close supervision
Korean Ginseng / Panax ginseng
May decrease effectiveness of drug:
One case reported
Check (low level of risk)
Meadowsweet (Filipendula ulmaria)
May increase effects of drug.
Theoretical concern based on animal studies (in vivo) which showed anticoagulant activity.
Check (low level of risk)
St John’s Wort (Hypericum perforatum)
Decreases drug levels
Cases reported
Contraindicated.
Willow Bark (Salix alba, Salix daphnoides, Salix purpurea, Salix fragilis)
May increase effects of drug.
A very mild but significant antiplatelet activity was observed in a Clinical study
Check (low level of risk)