Herb-Drug Interactions: Cat’s claw

Uncaria tomentosa DC, Uncaria guianensis J.F.Gmel. (Rubiaceae) Synonym(s) and related species Life-giving vine of Peru, Samento, Saventaro, Una de gato. Pharmacopoeias Cat’s Claw (US Ph 32); Powdered Cat’s Claw (US Ph 32); Powdered Cat’s Claw Extract (US Ph 32); Cat’s Claw Tablets (US Ph 32); Cat’s Claw Capsules (The United States Ph 32). Constituents The main constituents of both the closely related species of cat’s claw include the tetracyclic oxindole alkaloids, isorhynchophylline and rhynchophylline, and the indole alkaloids, dihydrocoryynantheine, hirsutine, and hirsuteine. Quinovic acid glycosides have also been isolated. Note that there are two chemotypes of Uncaria tomentosa, one primarily containing the tetracyclic oxindole alkaloids, isorhynochophylline and rhynchopylline, and one primarily containing the pentacychc oxindole alkaloids, (iso)pteropodine and (iso)mitraphylline. Use and indications Cat’s claw roots, bark and leaves have been used for gastric ulcers, arthritis, gonorrhoea, dysentry, herpes zoster, herpes simplex and HIV, and as a contraceptive. In various preclinical studies, antiviral, anti-inflammatory, antirheumatic, immunostimulating, antimutagenic, antitumour and hypotensive Read more […]

Herb-Drug Interactions: Willow

Salix species (Salicaceae) Synonym(s) and related species European willow, Salix, White willow. Salix alba L., Salix cinerea L., Salix daphnoides, Salix fragilis L., Salix pentandra L., Salix purpurea L. Pharmacopoeias Willow Bark (British Ph 2009, European Ph 2008); Willow Bark Dry Extract (British Ph 2009, European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4). Constituents The bark of willow contains the phenolic glycosides salicin (up to 10%), acetylsalicin, salicortin, salireposide, picein, triandrin. Esters of salicylic acid and salicyl alcohol, and flavonoids and tannins are also present. Extracts are sometimes standardised to a minimum of 1.5% of total salicylic derivatives, expressed as salicin (British Ph 2009, European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4). Use and indications The bark of willow is reported to have analgesic, anti-inflammatory, antipyretic and astringent properties. It has long been used for treating all kinds of fevers, headache, influenza, rheumatism, gout and arthritis. Pharmacokinetics In a pharmacokinetic study, 10 healthy subjects were given two oral doses of Salix purpurea bark extract, each standardised to contain 120 mg of salicin, 3 Read more […]

Herb-Drug Interactions: Tea

Camellia sinensis (L.) Kuntze (Theaceae) Synonym(s) and related species Camellia thea Link, Thea sinensis L. Note that Green tea (predominantly produced in China and Japan) is produced from steam-treated tea leaves. Black tea or Red tea (predominantly produced in India, Sri Lanka and Kenya) is processed by fermentation and heating, whereas Oolong tea is partially fermented. Pharmacopoeias Powdered Decaffeinated Green Tea Extract (The United States Ph 32). Constituents Tea contains caffeine (around 1 to 5%), with minor amounts of other xanthines such as theophylline and theobromine. Tea also contains flavonoids, the content of which varies between green (unfermented) and black (fermented) tea. Green tea appears to contain greater quantities of the flavonol-type flavonoids than black tea. Black tea also contains theaflavins, which are produced during the fermentation process. Other flavonols present include quercetin and kaempferol. Oolong tea contains some unique flavones known as oolonghomobisflavins. Tea also contains up to 24% tannins. Use and indications The leaf buds and very young leaves of tea are used as a stimulant and diuretic, actions that can be attributed to the caffeine content. They are Read more […]

Herb-Drug Interactions: Resveratrol

Types, sources and related compounds Resveratrol is a polyphenol present in most grape and wine products and is the compound largely credited with providing the health benefits of red wine. However, the concentration is very variable between foods and supplements, so it is difficult to evaluate the clinical relevance of the available information. Use and indications Resveratrol is used for its reputed anti-ageing effects. It is said to have antioxidant properties and antiplatelet effects, and is therefore promoted as having benefits in a variety of cardiovascular diseases, including atherosclerosis. It also has some oestrogenic and anti-inflammatory activity, and is under investigation in the prevention and treatment of cancer, because it appears to reduce cell proliferation. Pharmacokinetics An in vitro study reported that resveratrol inhibited the cytochrome P450 isoenzyme CYP3A4, but was much less potent than erythromycin, a known, clinically relevant, moderate CYP3A4 inhibitor. Similar results were found in other studies. Interestingly, red wine also inhibited CYP3A4, but this effect did not correlate with the resveratrol content. In other studies resveratrol had only very weak inhibitory effects on CYP1A2, Read more […]

Herb-Drug Interactions: Ginkgo

Ginkgo biloba L. (Ginkgoaceae) Synonym(s) and related species Fossil tree, Kew tree, Maidenhair tree. Salisburia adiantifolia Sm., Salisburia biloba Hoffmanns. Pharmacopoeias Ginkgo (US Ph 32); Ginkgo capsules (US Ph 32); Ginkgo dry extract, refined and quantified (British Ph 2009, European Ph 2008); Ginkgo leaf (British Ph 2009, European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4); Ginkgo tablets (US Ph 32); Powdered ginkgo extract (The United States Ph 32). Constituents Ginkgo leaves contain numerous flavonoids including the biflavone glycosides such as ginkgetin, isoginkgetin, bilobetin, sciadopitysin, and also some quercetin and kaempferol derivatives. Terpene lactones are the other major component, and these include ginkgolides A, B and C, and bilobalide, Ginkgo extracts may be standardised to contain between 22 and 27% flavonoids (flavone glycosides) and between 5 and 12% terpene lactones, both on the dried basis. The leaves contain only minor amounts of ginkgolic acids, and some pharmacopoeias specify a limit for these. The seeds contain ginkgotoxin (4-O-methylpyridoxine) and ginkgolic acids. Use and indications The leaves of ginkgo are the part usually used. Ginkgo is often used Read more […]

Herb-Drug Interactions: Feverfew

Tanacetum parthenium Sch.Bip. (Asteraceae) Synonym(s) and related species Altamisa, Featherfew, Featherfoil, Midsummer daisy. Chrysanthemum parthenium (L.) Bernh., Leucanthemum parthenium (L.) Gren & Godron, Pyrethrum parthenium (L.) Sm. Pharmacopoeias Feverfew (British Ph 2009, European Ph 2008, US Ph 32); Powdered Feverfew (The United States Ph 32). Constituents The leaf and aerial parts contain sesquiterpene lactones, especially parthenolide, its esters and other derivatives, santamarin, reynosin, artemorin, partholide, chrysanthemonin and others. The volatile oil is composed mainly of alpha-pinene, bornyl acetate, bornyl angelate, costic acid, camphor and spirotekal ethers. Use and indications Feverfew is mainly used for the prophylactic treatment of migraine and tension headache, but it has antiplatelet and anti-inflammatory activity, and has been used for coughs, colds and rheumatic conditions. It can cause allergic and cytotoxic reactions due to the presence of sesquiterpene lactones with an alpha-methylene butyrolactone ring, as in parthenolide. Pharmacokinetics In a study investigating the in vitro inhibitory potency of an extract of feverfew using a commercially available mixture of cytochrome Read more […]