Clinical trials with hypericum extracts in patients with depression--results, comparisons, conclusions for therapy with antidepressant drugs.

By the spring of 2002, results from 34 controlled, double-blind trials of Hypericum extracts in some 3000 patients, predominantly with mild to moderate forms of depression, had been published. An overview is given of the studies conducted since 1990. In the majority of them, the efficacy criterion (primary endpoint) was the score and/or response rate on the Hamilton Rating Scale of Depression (HAMD). In ten studies, based on extracts prepared with 50% or 60% ethanol in water (V/V), the dosages ranged from 300 mg to 1050 mg of extract per day. Five of the ten studies were placebo-controlled and in all five cases, the Hypericum extract was shown to be significantly superior. Results with Hypericum were as good or even better than with imipramine or fluoxetine. In the period since 1990, a total of twelve controlled trials have been published with one particular extract prepared with 80% methanol in water (V/V), of which six were placebo-controlled, two compared Hypericum with imipramine and one each with maprotiline, amitriptyline, sertraline or light therapy. Dosages ranged from 450-1200 mg extract per day. Statistical analysis of the total Hamilton scores showed significant differences between Hypericum extract and placebo in four of the six placebo-controlled studies and a trend in favour of the active treatment in the other two. Of the five comparative trials against four different synthetic antidepressants, amitriptyline was significantly superior to Hypericum after six weeks of therapy, whilst there were no significant differences in treatment outcome between Hypericum and the other synthetics in the remaining four studies. The results of the trials conducted to date show no major differences in efficacy of the alcoholic extracts. Taking all the results into account, it can be assumed that the threshold dose for efficacy against individual symptoms and complaints that occur in the course of the depressive illness could be about 300 mg of extract per day. In the medically supervised treatment of mild to moderate depression, doses of approximately 500-1000 mg of extract per day of these preparations of St. John's Wort are of comparable efficacy to synthetic antidepressants in their normally prescribed dosages.