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 […]

Echinacea (E. angustifolia, E. purpurea, and E. pallida)

Echinacea: Medical Uses Echinacea is used for the common cold, infections, and low immune status. It is given with antibiotics and chemotherapy and acts as an anti-inflammatory. Historical Uses Native Americans and Eclectic physicians used echinacea as a natural anti-infective for colds and flu. Native Americans first introduced echinacea to the colonists. Growth There are nine species of echinacea. This perennial will grow in most herb gardens in the northeast. The beautiful flower of E. purpurea, commonly called “purple cone-flower,” may grow up to 6 feet tall. E. angustifolia has narrow leaves and is much shorter, at about 2 feet. It has pink flowers. E. pallida grows to about 3 feet and is much paler. All three species have been cultivated in the U.S. and Europe. E. angustifolia is listed as an at-risk endangered herb. Parts Used • Aerial (above-ground) parts • Whole plant and root Major Chemical Compounds • Alkylamides • Caffeic acid derivatives • Cichoric acid • Polysaccharides • Glycoproteins Not all active chemical compounds are found in each species of echinacea. Mechanism of Action Alkylamides, which cause a tingling sensation on the tongue, produce anti-inflammatory 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: 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 […]

Grapeseed extract: Uses. Dosage

Clinical Use Free radical damage has been strongly associated with virtually every chronic degenerative disease, including cardiovascular disease, arthritis and cancer. Clearly, due to the potent antioxidant activity of grapeseed, its therapeutic potential is quite broad. Most clinical studies have been conducted in Europe using a commercial product known as Endotelon®. Due to the poor bioavailability of high-molecular-weight proanthocyanidins, it is advised that products containing chiefly low-molecular-weight PCs be used in practice. FLUID RETENTION, PERIPHERAL VENOUS INSUFFICIENCY AND CAPILLARY RESISTANCE Several clinical studies have investigated the use of grapeseed extract in fluid retention, capillary resistance or venous insufficiency, producing positive results. Hormone replacement therapy and fluctuations in hormone levels can produce symptoms of venous insufficiency in some women. One large study involving 4729 subjects with peripheral venous insufficiency due to HRT showed that grapeseed extract decreased the sensation of heaviness in the legs in just over half the subjects by day 45 whereas 89.4% of subjects experienced an improvement by day 90. According to an open multicentre study of women aged Read more […]


ANTIARRHYTHMIC AGENTS (antidysrhythmic agents) are used to treat a number of heart conditions characterized by irregularities of heart beat. They have been classified under the Vaughan Williams Scheme, though not all clinically used agents neatly fit these classes. Class I (which has a number of subtypes) is mainly used to treat atrial and ventricular tachycardias, and contains a number of SODIUM-CHANNEL BLOCKERS, e.g. disopyramide, flecainide, lignocaine, procainamide and quinidine. Class II, which is valuable for stress-induced tachycardias, contains β-ADRENOCEPTOR ANTAGONISTS, e.g. metoprolol, propranolol. Class III, which is used for certain tachycardia syndromes, includes amiodarone (whose mechanism of action is not clear), POTASSIUM-CHANNEL BLOCKERS and the atypical β-blocker sotalol. Class IV is used for atrial tachyarrhythmias and contains certain CALCIUM-CHANNEL BLOCKERS, e.g. diltiazem and verapamil. In addition to drugs in these classes, others may be used for certain arrhythmias. Digoxin may be used for treatment of atrial fibrillation, adrenaline for asystolic cardiac arrest, atropine for sinus bradycardia, methacholine (rarely) for supraventricular tachycardia, magnesium salts for ventricular Read more […]