anticoagulant and antiplatelet drugs as concomitant use might increase the risk of bleeding due to decreased platelet aggregation. Some of these drugs include aspirin, clopidogrel (Plavix), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others. Clinical research shows that taking a specific ginkgo extract called EGb 761 (Dr. Willmar Schwabe Pharmaceuticals) for 4 weeks can modestly reduce symptoms of anxiety in a greater percentage of adults with generalized anxiety disorder or adjustment disorder with anxious mood when compared with placebo. After 4 weeks of treatment, a reduction in anxiety rating score of at least 50% was seen in 44% of patients treated with 480 mg daily, 39% of patients treated with 240 mg daily, and 22% of patients treated with placebo (Woelk, Arnoldt, Kieser, & Hoerr, 2007). It is unclear whether these effects would persist when taken for longer than 4 weeks. Oral ginkgo 240 mg seems to improve symptoms of various types of dementia, but lower doses are not always effective. Oral ginkgo does not seem to prevent or slow down the progression of dementia (Wang, Wang, Song, Qi, Rong, Wang, Zhang, & Chen, 2010). Few clinical studies compare ginkgo leaf extract to conventional drugs such as cholinesterase inhibitors. Some preliminary comparative studies show that taking a specific ginkgo leaf extract called EGb 761 (Dr. Willmar Schwabe Pharmaceuticals) 160-240 mg daily for 22-24 weeks seems to be comparable to donepezil (Aricept) 5-10 mg daily for mild to moderate Alzheimer disease (Pennisi, 2006). Taking ginkgo leaf extract orally 80 mg twice daily or 40 mg three times daily seems to produce significant relief in breast tenderness and other physical and psychological symptoms associated with PMS when started during the 16th day of the menstrual cycle and continued until the 5th day of the following cycle for up to two cycles (Tamborini, & Taurelle, 1993). Some clinical research suggests that black cohosh might modestly inhibit cytochrome P450 2D6 (CYP2D6) and increase levels of drugs such as codeine and hydrocodone that are metabolized by this enzyme (Gorman, Coward, Darby, & Rasberry, 2013; Gurley et al., 2005). However, contradictory clinical research shows a specific black cohosh product (Remifemin, Enzymatic Therapy) 40 mg twice daily does not significantly inhibit metabolism of a CYP2D6 substrate in healthy study volunteers (Gurley et al., 2008). Until more is known, black cohosh should be used cautiously or avoided in patients taking drugs such as codeine and hydrocodone. From a dental perspective, these drugs should not be prescribed for postoperative dental pain – especially in patients who may concurrently consume black cohosh.
anticoagulant drugs. This interaction has not been reported in humans; however, contradictory case reports suggest that green tea might actually decrease the anticoagulant effect of warfarin. This could be due to vitamin K or other constituents contained in green tea. Until more is known, green tea should be used cautiously in combination with Ginko Ginkgo biloba is the oldest living species of tree on earth originating two hundred million years ago. It is native to temperate Asia, including China, Japan, and Korea, but is now cultivated in Europe and the United States. Ginkgo has a long history of use in traditional Chinese medicine and ginkgo leaf preparations have been used to treat cerebral insufficiency, peripheral vascular disease, attention and memory loss, and vertigo and tinnitus. There have been over four hundred scientific studies conducted on proprietary standardized extracts of the ginkgo leaf in the past 30 years. Standardized ginkgo leaf extracts have been used safely in trials lasting for several weeks up to 6 years. There is some concern about toxic and carcinogenic effects seen in animals exposed to a ginkgo leaf extract containing 31.2% flavonoids, 15.4% terpenoids, and 10.45 ppm ginkgolic acid, in doses of 100 to 2000 mg/kg five times per week for 2 years (National Toxicology Program, 2013). However, the clinical relevance of this data for humans, using typical doses, is unclear. The content of the extract used is not identical to that commonly used in supplement products, and the doses studied are much higher than those typically used by humans. A single dose of 50 mg/kg in rats is estimated to be equivalent to a single dose of about 240 mg in humans (National Toxicology Program, 2013). There is concern that ginkgo might have labor- inducing and hormonal effects. There is also concern that the antiplatelet effects of ginkgo could prolong bleeding time if taken around the time of labor and delivery (Dugoua, Mills, Perri, & Koren, 2006). Theoretically, ginkgo might adversely affect pregnancy outcome; avoid using during pregnancy. Black cohosh Black cohosh is taken orally for symptoms of menopause; to induce labor in pregnant women; for premenstrual syndrome, dysmenorrhea, nervous tension, dyspepsia, rheumatism, fever, sore throat, and cough; as an insect repellent; and as a mild sedative. Topically, black cohosh is used to treat acne, remove moles and warts, improve the appearance of the skin, and treat rattlesnake bites. For all these indications, only in the case of menopausal symptoms (hot flashes) has the medical literature suggested that this herbal supplement may be effective. However, there is considerable variability in the preparations used in clinical trials and in the results obtained (Jiang et al., 2015; Shams et al., 2010; Taylor, 2015).
ADDITIONAL HERBAL-DRUG INTERACTIONS OF NOTE
those that have been described so far, but for which the consequences of not recognizing and avoiding these potential herbal- drug interactions could be severe. These additional herbal-drug interactions all have an interaction rating of “major.” In other words, these combinations are not to be used. Concomitant use of the drug and herbal supplement is contraindicated and could lead to a serious adverse outcome.
Although the compilation of herbal-drug interactions listed in Table 6 summarizes the findings of evidence- based interactions of greatest clinical concern between medications commonly used by dentists and those herbal supplements most commonly used in the United States, there are some additional herbal-drug interactions of which OHCPs should be aware. Table 8 highlights these interactions, which may have a lower prevalence than
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