In Germany, hypericum extracts are among the most widely prescribed antidepressants.
Additionally, many preparations of St. John's wort are sold on the free market and
one extract is even the best selling antidepressant in the country. In contrast to
synthetic antidepressants, the approval procedures are not so strict, which implies
that the pharmaceutical industry is not forced to conduct clinical trials suitable
for licensing. Nevertheless, numerous studies on hypericum extracts including depressed
patients have been published in the last 20 years. The purpose of this paper is to
review these investigations in respect of methodological considerations and to draw
conclusions pertaining to the proof of antidepressant efficacy. To this effect, a
computer-assisted literature research was performed and manufacturers were asked to
supply the author with study results. A total of 12 placebo-controlled trials with
hypericum extracts were performed, mostly with positive results. Also in comparison
with synthetic antidepressants (3 studies published), a similar reduction of depressive
symptomatology was seen, although the comparators were not adequately dosed. No trials
in severely depressed patients have been published yet. Since most studies on hypericum
have methodological flaws, further studies are warranted.
