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: Parsley

Petroselinum crispum (Mill.) A.W.HiII (Apiaceae) Synonym(s) and related species Apium petroselinum L., Carum petroselinum (L.) Benth., Petroselinum peregrinum (L.) Lag., Petroselinum sativum Hoffm., Petroselinum vulgare Lag. Constituents All parts of the parsley plant contain similar compounds but possibly in different proportions. The most important constituents are the natural coumarins (furanocoumarins including bergapten, psoralen, 8- and 5-methoxypsoralen), and the phthalides Z-ligustilide, cnidilide, neocnidilide and senkyunolide. Flavonoids present include apigenin, luteolin and others. There is also a small amount of volatile oil present, in all parts but especially the seed, containing apiole, myristicin, eugenol, osthole, carotol and others. Use and indications Parsley root and seed are traditionally used as a diuretic, carminative and for arthritis, rheumatism and other inflammatory disorders. The leaves are used as a culinary herb in foods. Pharmacokinetics A small study in mice reported that a parsley root extract reduced the liver content of cytochrome P450 when compared with control animals. The general significance of this is unclear and further study is needed. For information on the pharmacokinetics Read more […]

Herb-Drug Interactions: Horsetail

Equisetum arvense L. (Equisetaceae) Synonym(s) and related species Equisetum. The related species Equisetum hyemale L. has also been used, but note that standardised pharmacopoeial preparations of horsetail should contain no more than 5% of other Equisetum species. Pharmacopoeias Equisetum Stem (Ph Eur 6.04); Horsetail (British Pharmacopoeia 2009). Constituents Horsetail contains high concentrations of silicic acid, up to 8%, and is sometimes used as an organic source of silicon. It also contains flavonoids such as apigenin, kaempferol, luteolin and quercetin and their derivatives, and may be standardised to the total flavonoid content expressed as isoquercitroside. Other polyphenolic compounds such as caffeic acid derivatives, and trace amounts of the alkaloid nicotine, and sterols including cholesterol, isofucosterol and campesterol, are also present. Horsetail also contains thiaminase (an enzyme that breaks down thiamine), and this is inactivated in some supplements. Use and indications Horsetail is used mainly as an astringent, haemostatic and anti-inflammatory agent, and for urinary tract complaints such as cystitis, prostatitis, urethritis and enuresis. There is little pharmacological, and no clinical, Read more […]

Iodine: Deficiency Signs and Symptoms

PRIMARY DEFICIENCY Iodine deficiency results when iodide intake is <20 µg/day. In situations of moderate deficiency, TSH induces thyroid hypertrophy in order to concentrate iodide, resulting in a goitre. Most of these cases remain euthyroid, but in cases of severe iodine deficiency, myxoedema may result in adults and cretinism in infants, both of which are serious conditions. Myxoedema is characterised by swelling of the hands, face, feet and peri-orbital tissues and can lead to coma and death if sufficiently severe and left untreated. Endemic cretinism is divided into two forms, neurologic or myxoedematous, depending on the interplay of genetics and iodine deficiency. Usually children with neurologic cretinism are mentally deficient and often deaf mute but of normal height and strength and may have goitre. Myxoedematous cretinism is characterised by dwarfism, mental deficiency, dry skin, large tongue, umbilical hernia, muscular incoordination and puffy facial features. Concomitant selenium deficiency may be a contributing factor in myxoedematous cretinism. Early treatment with thyroid hormone supplementation can promote normal physical growth; however, intellectual disability may not be prevented and in very Read more […]


ANTIDEPRESSANTS are used to relieve the symptoms of depressive illness, an affective disorder. There are three main groups of drugs used for the purpose. All interfere with the function of monoamine neurotransmitters, and the considerable delay before antidepressants become effective is taken as evidence of a down-regulation of noradrenergic or serotonergic systems (rather than the opposite, as advanced in Schildkraut’s original amine theory of depression). Tricyclic antidepressants are the oldest group (named after the chemical structure of the original members) .e.g. imipramine. They act principally as CNS monoamine (re-) UPTAKE INHIBITORS. Although far from ideal, this is still the most-used antidepressant group. Chemically, they have gone through transformations from the dibenzazepines (e.g. imipramine, desipramine), to dibenzcycloheptenes (e.g. amitriptyline, nortryptyline), dibenzoxepines (e.g. doxepin) and some recent members are not strictly tricyclics. They are effective in alleviating a number of depressive symptoms, though they have troublesome anticholinergic and other side-effects. Most drugs of this class also have sedative properties, which is more pronounced in some, especially amitriptyline, which Read more […]

Slippery elm: Toxicity. Adverse Reactions. Interactions. Pregnancy Use

Insufficient reliable information is available. Adverse Reactions Insufficient reliable information is available. Significant Interactions Controlled studies are unavailable, but interactions are theoretically possible with some medicines. Since slippery elm forms an inert barrier over the gastrointestinal lining, it may theoretically alter the rate and/or extent of absorption of medicines with a narrow therapeutic range (e.g. barbiturates, digoxin, lithium, phenytoin, warfarin). The clinical significance of this is unclear. Separate doses by 2 hours. Contraindications and Precautions Insufficient reliable information is available. Pregnancy Use Insufficient reliable information is available.