Herb-drug interactions

Concurrent use of herbs may mimic, magnify, or oppose the effect of drugs. Plausible cases of herb-drug interactions include: bleeding when warfarin is combined with ginkgo (Ginkgo biloba), garlic (Allium sativum), dong quai (Angelica sinensis), or danshen (Salvia miltiorrhiza); mild serotonin syndrome in patients who mix St John's wort (Hypericum perforatum) with serotonin-reuptake inhibitors; decreased bioavailability of digoxin, theophylline, cyclosporin, and phenprocoumon when these drugs are combined with St John's wort; induction of mania in depressed patients who mix antidepressants and Panax ginseng; exacerbation of extrapyramidal effects with neuroleptic drugs and betel nut (Areca catechu); increased risk of hypertension when tricyclic antidepressants are combined with yohimbine (Pausinystalia yohimbe); potentiation of oral and topical corticosteroids by liquorice (Glycyrrhiza glabra); decreased blood concentrations of prednisolone when taken with the Chinese herbal product xaio chai hu tang (sho-salko-to); and decreased concentrations of phenytoin when combined with the Ayurvedic syrup shankhapushpi. Anthranoid-containing plants (including senna [Cassia senna] and cascara [Rhamnus purshiana]) and soluble fibres (including guar gum and psyllium) can decrease the absorption of drugs. Many reports of herb-drug interactions are sketchy and lack laboratory analysis of suspect preparations. Health-care practitioners should caution patients against mixing herbs and pharmaceutical drugs.     

Ginkgo biloba precipitating epileptic seizures

BACKGROUND: The herbal remedy Ginkgo biloba is promoted as a treatment for a variety of ailments including memory loss and dementia, poor concentration and mood, glaucoma, 'cerebral insufficiency' and 'peripheral circulatory disturbances'. It is gaining worldwide popularity, particularly as a potential treatment for dementia. CASE REPORTS: Two patients with well-controlled epilepsy presented with recurrent seizures within 2 weeks of commencing extract of Ginkgo biloba. The herbal remedy was discontinued and both patients are seizure-free several months later. DISCUSSION: Ginkgo biloba may have precipitated seizures in these two patients. This and other potential adverse effects should be highlighted on the packaging of the drug.     

Fibrinolytic effects of Ginkgo biloba extract

A multitude of factors are involved in regulating the blood coagulation homeostatic processes in the body, which may ultimately lead to thromboemboli and thrombosis. The resolution of blood clots after healing is as important as clot formation at the site of a vascular lesion. This is accomplished by fibrinolytic drugs such as streptokinase (SK) and urokinase.     

Drug interactions between opioids and antiretroviral medications: interaction between methadone, LAAM, and nelfinavir

Understanding drug interactions between antiretrovirals and opiate therapies may decrease toxicities and enhance adherence, with improved HIV outcomes in injection drug users. We report results of a clinical pharmacology study designed to examine the interaction of the protease inhibitor, nelfinavir, with methadone and LAAM (N = 48). Nelfinavir decreased methadone exposure, but no withdrawal was observed over the five day study period. LAAM and dinorLAAM concentrations were decreased, while norLAAM concentrations were increased, with minimal overall change in LAAM/metabolite exposure. Methadone and LAAM did not affect nelfinavir concentrations, but methadone decreased M8 metabolite exposure. While no toxicities were observed, clinicians should be aware of the potential for drug interactions when patients require treatment with nelfinavir and these opiate medications.     

Superoxide dismutase activity of Ginkgo biloba extract]

The Ginkgo biloba extract is obtained from green leaves of the Ginkgo biloba tree. Preparations with this active substance are among others used for the treatment of disturbances of the cerebral function and arteriosclerotic diseases. In in-vitro and in-vivo studies antagonistic effects of radical scavenger and PAF (platelet activating factor) were described. In this study a concentration-depending superoxide dismutase activity of the Ginkgo biloba extract r?kan liquid could be made evident.     

The use of Ginkgo biloba in healthy elderly

To promote health-conscious behavior in the aging society and gain insight into the sources of knowledge on which preventive strategies are based, analyzing the behavior of elderly people who are recognized as highly health conscious may be useful. We focused on the use of Ginkgo biloba, which is commonly considered to be effective in preventing cognitive decline and dementia, among elderly adults. A total of 1,672 questionnaires were distributed among geriatric participants (60–94 years) who attended university lectures at 22 universities throughout Germany. Response rate was 36.1 %. We collected data on demographic characteristics, preventive strategies (use of Ginkgo and other supplements), health-conscious behavior, sources of knowledge concerning health behavior, and factors associated with the participants’ concept of aging. The prevalence of Ginkgo use was 15.3 %. Ginkgo was assumed to be effective for cognitive enhancement and the treatment of cognitive decline by two thirds of the surveyed participants and one third believed Ginkgo to be effective for preventing dementia. Ginkgo use was significantly higher among participants using natural remedies and herbal and food supplements. The use of Ginkgo was recommended by physicians (57.3 %), chemists (16 %), and healthcare magazines (10.7 %). Food supplements were taken by 65.8 % of the sample: this percentage was significantly higher among subjects who exhibited health-conscious behavior. “Knowledge” about strategies to enhance cognition or prevent cognitive decline among the elderly do not appear to be evidence based. Thus, there is a need to establish reliable and independent sources of scientific information for healthcare professionals and the general public.