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 […]

Herbal Medicines

Herbal medicines are medicines made from plants. A survey of some 259 of the most widely used plants in western herbal medicine in Australia found that the vast majority are flowering plants (angiosperms). Approximately one-third of the species belong to just five botanical families: the daisy family (Asteraceae), mint family (Lamiaceae), rose family (Rosaceae), carrot family (Apiaceae) and legume family (Fabaceae). The study also surveyed the biogeographical origin of medicinal species and the morphological plant parts used for medicinal purposes. These results are shown in Table Biogeographical origin of 259 species used in western herbal medicine and Table Morphological plant part used for medicine respectively. Table Biogeographical origin of 259 species used in western herbal medicine (after Wohlmuth 2002) Europe/Europe and parts of Asia 37.4% Asia 19.3% Africa 3.0% North America 21.6% South America 3.5% Pacific (incl. Australia) 1.2% Native to several continents 14.0% Table Morphological plant part used for medicine (after Wohlmuth 2002) Plant part used Aerial parts 37.8% Underground parts 27.8% Fruit/seed 13.9% Bark 8.5% Flower 4.6% Herbal Read more […]


ANTIHYPERLIPIDAEMIC AGENTS (lipid-lowering drugs, antihypercholesterolaemic agents, lipid-regulating drugs) are used in clinical conditions of hyperlipidaemia, where there are very high levels of the lipids cholesterol and/or triglycerides in the blood plasma, and more generally in the treatment of coronary heart disease. Medical evidence suggests that if diet or drugs can be used to lower levels of LDL-cholesterol (low-density lipoprotein), whilst raising HDL-cholesterol (high-density lipoprotein), then there may be a regression of the progress of coronary atherosclerosis — a diseased state of the arteries of the heart where plaques of lipid material narrow blood vessels, which contributes to angina pectoris attacks, and to the formation of abnormal clots which go on to cause heart attacks and strokes. The initial use of lipid-lowering drugs was mainly only in familial hyperlipidaemia, or where distinct clinical signs indicate the need for intervention. In most individuals an appropriate type of low fat diet can adequately do what is required, but the agents are now used more in treating a range of cardiovascular diseases. Lipid-lowering drugs work in several ways. The polymeric ion-exchange resins cholestyramine 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: Saw palmetto

Serenoa repens (Bartram) J.K. Small (Arecaceae) Synonym(s) and related species American dwarf palm, Sabal, Serenoa. Brahea serrulata H.Wendl., Sabal serrulata (Michx.) Schult f., Sabal serrulatum Schult f., Serenoa serrulata (Michx.) Hook. f. ex B.D. Jacks. Pharmacopoeias Powdered Saw Palmetto (US Ph 32); Saw Palmetto (US Ph 32); Saw Palmetto Capsules (US Ph 32); Saw Palmetto Fruit (British Ph 2009, European Ph, 6th ed., 2008 and Supplements 6.1, 6.2, 6.3 and 6.4). Constituents The fruit of saw palmetto contains about 25% fatty acids (extracts are often standardised to a minimum of 11% total fatty acids) consisting of capric, caprylic, lauric, palmitic, oleic, linoleic and linolenic acids in the form of fixed oils. Sterols including campesterol, stig masterol and beta-sitosterol are also present, as are long-chain alcohols, carotenoids, various polysaccharides and some flavonoids, including rutin, isoquercetin and kaempferol. Use and indications The main contemporary use of saw palmetto fruit is to treat the urological symptoms of benign prostatic hyperplasia. It has also been used as a diuretic, a sedative, an endocrine agent, an antiseptic and for treating disorders involving the sex hormones. Pharmacokinetics Saw Read more […]

Herb-Drug Interactions: Natural coumarins

Natural coumarins are widespread in herbal medicines and vegetables. There is a misconception that if a plant contains natural coumarins it will have anticoagulant properties, but very specific structural requirements are necessary for this – namely there must be a non-polar carbon substituent at the 3-position of 4-hydroxycoumarin. Moreover, at present, there are no established interactions between warfarin and herbal medicines that have been attributed to the natural coumarin content of the herb. Even in the classic case of haemorrhagic death of livestock that led to the discovery of dicoumarol, it was the action of the mould on the natural coumarin in the sweet clover (melilot) that led to the production of the anticoagulant, so consumption of a spoiled product would seem to be necessary for this specific interaction to occur. This suggests that the occurrence of natural coumarins in dietary supplements or herbal medicines should not trigger immediate concern as regards interactions with anticoagulants. The information in this family monograph relates to the individual natural coumarins, and the reader is referred back to the herb (and vice versa) where appropriate. Note that, to avoid confusion with the synthetic Read more […]

Herb-Drug Interactions: Guggul

Commiphora wightii (Am.) Bhandari (Burseraceae) Synonym(s) and related species Mukul myrrh. Commiphora mukul Engl., Balsamodendrum wightii. Constituents The resinous sap, harvested from the tree bark by tapping, is extracted to produce guggul. Gugulipid is the purified standardised extract of crude gum guggul, and contains the active guggulsterone components Z-guggulsterone and E-guggulsterone, with cembrenoids, myrrhanone and myrrhanol derivatives. Use and indications Guggul is used mainly in Ayurvedic medicine and has been traditionally used to treat hypertension, osteoporosis, epilepsy, ulcers, cancer, obesity and rheumatoid arthritis. It is now often used for hyperlipidaemia, but clinical studies have found conflicting results for its lipid-lowering effects. Pharmacokinetics An in vitro study reported that gugulipid extract and purified guggulsterones may induce the expression of the cytochrome P450 isoenzyme CYP3A4. However, the clinical significance of this is unclear and further study is needed. Interactions overview In healthy subjects, the absorption of diltiazem and propranolol was modestly reduced by gugulipid. If the mechanism is confirmed, guggul might interact with a wide range of other Read more […]

Herb-Drug Interactions: Grapefruit

Citrus paradisi Macfad. (Rutaceae) Synonym(s) and related species Citrus paradisi Macfad. Grapefruit is a hybrid of the Pummelo or Pomelo (Citrus maxima (Burm.) Merr) with the sweet orange (Citrus sinensis (L.) Osbeck). Constituents Grapefruit contains furanocoumarins including bergamottin, 6′,7′-dihydroxybergamottin, bergapten, bergaptol, geranyl-coumarin and paradisin A, flavonoid glycosides such as naringin and flavonoid aglycones galangin, kaempferol, morin, naringenin, quercetin and others. The peel contains a volatile oil, mostly composed of limonene. Note that some grapefruit seed extracts have been found to contain preservatives such as benzethonium chloride, triclosan and methyl-p-hydroxybenzoate, which might be present because of the methods of production. Use and indications Grapefruit is used as a source of flavonoids (citrus bioflavonoids), which are widely used for their supposed antioxidant effects, and are covered under flavonoids. Grapefruit seed extracts are used for their antimicrobial properties, but there is some controversy that this might be due to preservative content rather than natural constituents. Grapefruit and grapefruit juice are commonly ingested as part of the diet, Read more […]

Herb-Drug Interactions: Flavonoids

Bioflavonoids The flavonoids are a large complex group of related compounds, which are widely available in the form of dietary supplements, as well as in the herbs or foods that they are originally derived from. They are the subject of intensive investigations and new information is constantly being published. You may have come to this monograph via a herb that contains flavonoids. Note that the information in this general monograph relates to the individual flavonoids, and the reader is referred back to the herb (and vice versa) where appropriate. It is very difficult to confidently predict whether a herb that contains one of the flavonoids mentioned will interact in the same way. The levels of the flavonoid in the particular herb can vary a great deal between specimens, related species, extracts and brands, and it is important to take this into account when viewing the interactions described below. Types, sources and related compounds Flavonoids are a very large family of polyphenolic compounds synthesised by plants that are common and widely distributed. With the exception of the flavanols (e.g. catechins) and their polymers, the proanthocyanidins, they usually occur naturally bound to one or more sugar molecules Read more […]

Policosanol: Clinical Use. Dosage

Most clinical studies have been conducted in Cuba with policosanol derived from sugar cane. HYPERLIPIDAEMIA Numerous randomised, double-blind clinical trials conducted prior to 2005 demonstrated significant cholesterol-lowering effects of oral policosanol; however, one recent study has produced negative results. Several previous studies conducted with postmenopausal women have confirmed efficacy in this population. Overall, these results show that a daily dose of 5 mg policosanol may: • reduce LDL-cholesterol by 11 -18% • reduce total cholesterol by 8-1 5% • increase HDL by 8-1 5% Whereas a higher dose of 20 mg policosanol daily can: • reduce LDL-cholesterol by 31% • reduce total cholesterol by 23% • increase HDL by 27%. Recent controversy It is important to note that previous research had been conducted almost entirely by the same research group in Cuba and involved Hispanic patients. In 2006, Berthold et al conducted a 12-week randomised study of 143 Caucasian subjects with hypercholesterolaemia or combined hyperlipidaemia. In contrast to previous studies, policosanol failed to significantly reduce LDL-cholesterol, total cholesterol, HDL-cholesterol, triglycerides and other lipid Read more […]