Herb-drug interactions: an evidence based approach.

The increasing use of herbal medicinal products (HMPs) in the community where people are also receiving prescription medicines suggests that adverse herb-drug interactions may be of significant public health consequence. The evidence available to guide practitioners in decision making is complex and consists of a range of sources including adverse event database entries, spontaneous or case reports, in vivo and in vitro drug metabolism studies, and in vivo drug interaction studies in healthy subjects and patients. In the absence of further rigorous studies to assess the clinical significance of herb-drug interactions, an evidence-based appraisal of the current literature is essential to guide practitioners involved in patient care.

Valerian does not appear to reduce symptoms for patients with chronic insomnia in general practice using a series of randomised n-of-1 trials.

OBJECTIVE: To investigate the effectiveness of valerian for the management of chronic insomnia in general practice. DESIGN: Valerian versus placebo in a series of n-of-1 trials, in Queensland, Australia. RESULTS: Of 42 enrolled patients, 24 (57%) had sufficient data for inclusion into the n-of-1 analysis. Response to valerian was fair for 23 (96%) participants evaluating their "energy level in the previous day" but poor or modest for all 24 (100%) participants' response to "total sleep time" and for 23 (96%) participants' response to "number of night awakenings" and "morning refreshment". As a group, the proportion of treatment successes ranged from 0.35 (95% CI 0.23, 0.47) to 0.55 (95% CI 0.43, 0.67) for the six elicited outcome sleep variables. There was no significant difference in the number (P=0.06), distribution (P=1.00) or severity (P=0.46) of side effects between valerian and placebo treatments. CONCLUSIONS: Valerian was not shown to be appreciably better than placebo in promoting sleep or sleep-related factors for any individual patient or for all patients as a group.