Asteraceae: Drug Interactions, Contraindications, And Precautions

Patient survey data from Canada, the U.S., and Australia show that one in five patients use prescription drugs concurrently with CAM. The inherent polypharmaceutical nature of complementary and alternative medicine increases the risk of adverse events if these complementary and alternative medicine either have pharmacological activity or interfere with drug metabolism. Since confirmed interactions are sporadic and based largely on case reports, advice to avoid certain drug-CAM combinations is based on known pharmacological and in vitro properties. Known Hypersensitivity to Asteraceae Cross-reactive sesquiterpene lactones are present in many, if not all, Asteraceae. Patients with known CAD from one plant may develop similar type IV reactions following contact with others. Affected patients are often advised to avoid contact with all Asteraceae, yet this advice is based on limited knowledge of cross-reactivity between relatively few members of this large family. Some authorities recommend avoiding Asteraceae-derived complementary and alternative medicine if, for example, the patient is known to have IgE-mediated inhalant allergy to ragweed. While a reasonable approach, this ignores a number of important facts: (1) Read more […]

Cerebrovascular Insufficiency And Depression

Atherosclerosis of the vasculature feeding the brain can lead to a condition known as cerebrovascular insufficiency. This chronic low-grade ischemia can impair memory or otherwise mimic dementia. It can also produce a syndrome resembling depression. This syndrome is surprisingly little discussed in the United States but is much more widely recognized in Europe. The treatment is obviously the same as for atherosclerosis anywhere in the body — elimination of the underlying dietary and lifestyle causes (especially sedentariness) and addition of supportive nutrients and practices (like meditation). Ginkgo biloba (ginkgo) leaf extracts have been very rigorously shown to help alleviate cerebrovascular insufficiency symptoms. This is almost certainly due to ginkgo’s ability to reduce the underlying atherosclerosis and improve neuron function despite ischemia. It also seems to stimulate blood flow to the brain, perhaps by acting on blood vessels. The usual dose of ginkgo standardized extract is 80-160 mg two or three times per day. It should be used attentively in patients taking anticoagulants as the combination occasionally but rarely may have a synergistic effect and cause bleeding. Gingko has also been shown to Read more […]

Herb-Drug Interactions: Cannabis

Cannabis sativa L. (Cannabaceae) Synonym(s) and related species Bhang, Dagga, Ganja, Hashish, Indian hemp, Marihuana, Marijuana. Cannabis indica Lam. Constituents Cannabis herb contains a wide range of cannabinoids, which are the major active compounds. The main psychoactive constituent is delta9-tetrahydrocannabinol (THC; dronabinol), and it is the cause of many of the pharmacological effects elicited by the consumption of cannabis. However, other cannabinoids, which do not possess psychoactive properties, such as cannabidiol, cannabinol (a decomposition product of delta9-tetrahydrocannabinol), cannabigerol and cannabichromene, are increasingly being investigated for their pharmacological and therapeutic properties. Cannabinoids are often found in the plant as their acid metabolites, e.g. ll-nor-9-carboxy-delta9-tetrahydrocannabinol, cannabidiol acid and others, especially if the plant has been grown in a cooler climate. These decarboxylate to the parent cannabinoid at high temperatures, such as during smoking. Most medicinal cannabis products have been heat treated to ensure that the cannabinoids are present only in the non-acid form. Use and indications Cannabis has no current established use in herbal Read more […]

Herb-Drug Interactions: St John’s wort

Hypericum perforatum L. (Clusiaceae) Synonym(s) and related species Hypericum, Millepertuis. Hypericum noeanum Boiss., Hypericum veronense Schrank. Pharmacopoeias St John’s Wort (British Ph 2009, European Ph 2008, US Ph 32); St John’s Wort Dry Extract, Quantified (British Ph 2009, European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4). Constituents The main groups of active constituents of St John’s wort are thought to be the anthraquinones, including hypericin, isohypericin, pseudohypericin, protohypericin, protopseudohypericin and cyclopseudohypericin, and the prenylated phloroglucinols, including hyperforin and adhyperforin. Flavonoids, which include kaempferol, quercetin, luteolin, hyperoside, isoquercitrin, quercitrin and rutin; biflavonoids, which include biapigenin and amentoflavone, and catechins are also present. Other polyphenolic constituents include caffeic and chlorogenic acids, and a volatile oil containing methyl-2-octane. Most St John’s wort products are standardised at least for their hypericin content (British Pharmacopoeia 2009), even though hyperforin is known to be a more relevant therapeutic constituent, and some preparations are now standardised for both (The United Read more […]

Herb-Drug Interactions: Milk thistle

Silybum mahanum (L.) Gaertn. (Asteraceae) Synonym(s) and related species Lady’s thistle, Marian thistle, Mediterranean milk thistle, St Mary’s thistle. Carduus marianus, Mariana lactea Hill. Pharmacopoeias Milk Thistle (US Ph 32); Milk Thistle Capsules (US Ph 32); Milk Thistle Fruit (British Ph 2009, European Ph 2008); Milk Thistle Tablets (US Ph 32); Powdered Milk Thistle (US Ph 32); Powdered Milk Thistle Extract (US Ph 32); Refined and Standardised Milk Thistle Dry Extract (British Ph 2009, European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4). Constituents The mature fruit (seed) of milk thistle contains silymarin, which is a mixture of the flavonolignans silibinin (silybin), silicristin (silychristin), silidianin (silydianin), isosilibinin and others. It may be standardised to contain not less than 1.5% (European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4), or not less than 2% (The United States Ph 32) of silymarin, expressed as silibinin (dried drug). Standardised extracts, containing high levels of silymarin, are often used. Milk thistle fruit also contains various other flavonoids, such as quercetin, and various sterols. Note that milk thistle leaves do not contain silymarin, Read more […]

Herb-Drug Interactions: Goldenseal

Hydrastis canadensis L. (Ranunculaceae) Synonym(s) and related species Hidrastis, Hydrastis, Orange root, Yellow root. Xanthorhiza simplicissima Marsh. Pharmacopoeias Goldenseal (US Ph 32); Goldenseal Rhizome (European Ph 2008); Goldenseal Root (British Ph 2009); Powdered Goldenseal (US Ph 32); Powdered Goldenseal Extract (The United States Ph 32). Constituents The rhizome of goldenseal contains the isoquinoline alkaloids hydrastine and berberine, to which it may be standardised, and also berberastine, hydrastinine, canadine (tetrahydroberberine), canalidine and others. Use and indications Used for inflammatory and infective conditions, such as amoebic dysentery and diarrhoea; gastric and liver disease. The alkaloids are antibacterial, amoebicidal and fungicidal. For details on the uses of berberine, a major constituent of goldenseal, see berberine. Pharmacokinetics In several in vitro studies, goldenseal root has been identified as a potent inhibitor of the cytochrome P450 isoenzyme CYP3A4, but more modest inhibitory effects were seen clinically with the CYP3A4 probe substrate, midazolam. Two studies in healthy subjects, found that goldenseal, given for 14 to 28 days, reduced the metabolism or urinary Read more […]

St Mary’s thistle: Background. Actions

Common Name St Mary’s thistle Other Names Carduus marianus, cardo bianco, cardo de burro, chandon marie, holy thistle, lady’s milk, lady’s thistle, Mariendistel, Marian thistle, Mary thistle, milk thistle, silybum, true thistle Botanical Name / Family Silybum marianum (family [Compositae] Asteraceae) Plant Part Used Ripe seed Chemical Components The major active constituents are the flavolignans, collectively named ‘silymarin’. The principal components of silymarin are silybin, isosilybin, silychristin and silydianin. Silybin makes up approximately 50% of silymarin and is regarded as one of the most biologically active constituents. There is also a fixed oil comprising linoleic, oleic and palmitic acids, tocopherol and sterols, including cholesterol, campesterol, stigmasterol and sitosterol. Historical Note St Mary’s thistle has a long history of traditional use since ancient times. Over the centuries, it has been touted as a remedy for snake bite, melancholy, liver conditions and promoting lactation. The name ‘milk thistle‘ derives from its characteristic spiked leaves with white veins, which according to legend, were believed to carry the milk of the Virgin Mary. St Mary’s thistle:  Main Actions Most Read more […]