Understanding drug interactions with St John's wort (Hypericum perforatum L.): impact of hyperforin content.

OBJECTIVE: The aim of this study was to review herb-drug interaction studies with St John's wort (Hypericum perforatum L.) with a focus on the hyperforin content of the extracts used in these studies. METHODS: PUBMED was systematically searched to identify studies describing pharmacokinetic interactions involving St John's wort. Data on study design and the St John's wort extract or product were gathered to extract hyperforin content and daily dose used in interaction studies. KEY FINDINGS: This analysis demonstrates that significant herb-drug interactions (resulting in a substantial change in systemic exposure) with St John's wort products were associated with hyperforin daily dosage. Products that had a daily dose of <1 mg hyperforin were less likely to be associated with major interaction for drugs that were CYP3A4 or p-glycoprotein substrates. Although a risk of interactions cannot be excluded even for low-dose hyperforin St. John's wort extracts, the use of products that result in a dose of not more than 1 mg hyperforin per day is recommended to minimise the risk of interactions. CONCLUSIONS: This review highlights that the significance of herb-drug interactions with St John's wort is influenced by the nature of the herbal medicines product, particularly the hyperforin content.

The Impact of Cocoa Flavanols on Cardiovascular Health.

The aim of the study was to review the effect of cocoa flavanols on cardiovascular health, with emphasis on the doses ingested, and to analyze a range of cocoa products for content of these compounds. PubMed was searched from 2010 to locate systematic reviews (SR) on clinical effects of chocolate consumption. Thirteen SRs were identified and reviewed, and provided strong evidence that dark chocolate did not reduce blood pressure. The evidence was however strong for an association with increased flow-mediated vasodilatation (FMD) and moderate for an improvement in blood glucose and lipid metabolism. Our analysis showed that cocoa products with around 100 mg epicatechin can reliably increase FMD, and that cocoa flavanol doses of around 900 mg or above may decrease blood pressure in specific individuals and/or if consumed over longer periods. Out of 32 cocoa product samples analyzed, the two food supplements delivered 900 mg of total flavanols and 100 mg epicatechin in doses of 7 g and 20 g and 3 and 8 g, respectively. To achieve these doses with chocolate, around 100 to 500 g (for 900 mg flavanols) and 50 to 200 g (for 100 mg epicatechin) would need to be consumed. Chocolate products marketed for their purported health benefits should therefore declare the amounts of total flavanols and epicatechin. Copyright © 2016 John Wiley & Sons, Ltd.

Best available evidence in cochrane reviews on herbal medicine?

Cochrane reviews are considered by many to be the "gold standard" or the final word in medical conversation on a topic. We explored the eleven most relevant Cochrane reviews on herbal medicine and identified that frequently herbal medicines in the included studies had not been sufficiently well characterised. If data on the effects of the plant parts are unavailable, effects of co-active ingredients need to be considered and the plausibility of the study medications for the specific indications discussed. Effect sizes calculated from exploratory studies would be best used to determine the sample sizes required for future confirmatory studies, rather than as definitive reports of intervention effects. Reviews should be comprehensive, including discussion of putative adverse events and possible drug interactions. We suggest that the guidelines for preparing Cochrane reviews be revised and offer assistance in this task.