The adoption of the EU community monograph on Hypericum constitutes a milestone in the process of harmonisation of herbal medicinal products within the European Community. Three different types of extracts have been granted a “well-established use” in the treatment of mild to moderate depression: a dry extract (3-7:1), manufactured with methanol 80 % (v/v); a dry extract (3-6:1), manufactured with 80 % ethanol (v/v), and a dry extract (2,-8:1), manufactured with 50-68 % ethanol (v/v) (Community Herbal Monograph on Hypericum perforatum L., herbal; EMA/HMPC/101304/2008). For these extract types the assessment of published clinical data revealed that the evidence of the efficacy in mild to moderate depressive episodes compared to placebo or standard medication was found to be acceptable. Additionally, a sufficient efficacy in relapse prophylaxis could be demonstrated. For some other dry extracts, the efficacy in the short-term treatment of symptoms in mild depressive disorders was found to be substantiated, and a Community Herbal Monograph was likewise established for the traditional use of other SJW preparations (EMA/HMPC/745582/2009).
These two monographs respectively the corresponding assessment report (EMA/HMPC/101303/2008) also allow concluding on a sufficient degree of safety. Treatment with preparations containing low to normal amounts of hyperforin did not increase cytochrome P450 enzyme activity, and is therefore not likely to cause herb-drug interactions. In the case that an applicant demonstrates that the daily intake of hyperforin is below 1 mg the warnings on interactions may even be omitted in traditional herbal medicinal products. Additionally, the cutaneous administration of traditional liquid herbal preparations for the traditional use in symptomatic treatment of minor inflammations of the skin and as an aid in healing minor wounds was included in the monograph 1.
Much effort has been invested in the identification of the active constituents responsible for the antidepressant activity of SJW. The results point to a combined and potentially synergistic effect of the various fractions of SJW extract. The lead substance hypericin and the flavonoids, as well as hyperforin display some interesting effects in pharmacological models, but none of the compounds tested to date appears indispensable for the overall efficacy 2. To date there is no known constituent of SJW extract with an antidepressant activity qualifying this constituent as representative for the total extract. The total extract must therefore be considered the active constituent.
This is especially apparent with the naphthodianthrone hyperforin. The pharmacodynamic effects observed with the latter have as yet not been demonstrated to be relevant for clinical application. In contrast, hyperforin was linked to pharmacokinetic interactions when administered with hyperforin-enriched extracts 3.
Studies on the pharmacokinetic characteristics of hypericin and pseudohypericin have been performed for the correlations of pharmacological data with isolated SJW constituents and therapeutic effects. These studies are presented in section 2 of this Clinical Summary.
1. Länger R. Die HMPC monograph zu Hypericum: Hintergründe, Entstehung, Inhalte. Wiener medizinische Wochenschrift. Dec 2010;160(21-22):557-563.
2. Butterweck V, Schmidt M. St. John's wort: role of active compounds for its mechanism of action and efficacy. Wiener medizinische Wochenschrift. 2007;157(13-14):356-361.
3. Madabushi R, Frank B, Drewelow B, Derendorf H, Butterweck V. Hyperforin in St. John's wort drug interactions. Eur.J.Clin Pharmacol. 2006;62(3):255-233.