Herbal Medicinals

Abstract

Herbal medicinals are being used by an increasing number of patients who typically do not advise their clinicians of concomitant use. Known or potential drug-herb interactions exist and should be screened for. If used beyond 8 weeks, Echinacea could cause hepatotoxicity and therefore should not be used with other known hepatoxic drugs, such as anabolic steroids, amiodarone, methotrexate, and ketoconazole. However, Echinacea lacks the 1,2 saturated necrine ring associated with hepatoxicity of pyrrolizidine alkaloids. Nonsteroidal anti-inflammatory drugs may negate the usefulness of feverfew in the treatment of migraine headaches. Feverfew, garlic, Ginkgo, ginger, and ginseng may alter bleeding time and should not be used concomitantly with warfarin sodium. Additionally, ginseng may cause headache, tremulousness, and manic episodes in patients treated with phenelzine sulfate. Ginseng should also not be used with estrogens or corticosteroids because of possible additive effects. Since the mechanism of action of St John wort is uncertain, concomitant use with monoamine oxidase inhibitors and selective serotonin reuptake inhibitors is ill advised. Valerian should not be used concomitantly with barbiturates because excessive sedation may occur. Kyushin, licorice, plantain, uzara root, hawthorn, and ginseng may interfere with either digoxin pharmacodynamically or with digoxin monitoring. Evening primrose oil and borage should not be used with anticonvulsants because they may lower the seizure threshold. Shankapulshpi, an Ayurvedic preparation, may decrease phenytoin levels as well as diminish drug efficacy. Kava when used with alprazolam has resulted in coma. Immunostimulants (eg, Echinacea and zinc) should not be given with immunosuppressants (eg, corticosteroids and cyclosporine). Tannic acids present in some herbs (eg, St John wort and saw palmetto) may inhibit the absorption of iron. Kelp as a source of iodine may interfere with thyroid replacement therapies. Licorice can offset the pharmacological effect of spironolactone. Numerous herbs (eg, karela and ginseng) may affect blood glucose levels and should not be used in patients with diabetes mellitus.

Effect ofCrataegusUsage in Cardiovascular Disease Prevention: An Evidence-Based Approach

“…WS 1442 activates rbcNOS and causes NO-formation in RBCs [55]. There is another opinion that hawthorn does have a vasodilating action both in the coronary circulation and the peripheral vasculature that may be mediated by inhibition of angiotensin-converting enzyme (ACE) [56]. …”

Herbal Therapy in Dermatology

“…The immunemodulating effects of Echinacea, Astragalus, licorice, alfalfa sprouts, vitamin E, and zinc may decrease the efficacy of corticosteroids and immunosuppressants. 88 There are herbs that have been shown to cause hepatitis and therefore should not be used in combination with such medications as methotrexate. These include many of the ingredients in the CHM preparations, as well as Echinacea, chaparral, germander, ragwort, and life root.…”

Regulation of CYP3A4 Expression in Human Hepatocytes by Pharmaceuticals and Natural Products

“…Given that many herbals are oxidized by drug-metabolizing enzymes, it is logical to expect interactions of herbal compounds with conventional drugs. Herbal use in the United States has been experiencing unprecedented growth, accounting for $3.24 billion in sales in 1997, and it has been estimated that the annual increase (from 1997 to 1998) in sales of St. John's wort and green tea extracts was 15,000 and 5,000%, respectively (Miller, 1998). The use of medicinal herbs has particularly increased over the past few years among specific patient populations including HIV-infected patients.…”