[Hypericum perforatum extract in treatment of mild to moderate depression. Clinical and pharmacological aspects].

For many years, hypericum extracts have been used in the treatment of depressive disorders. The therapeutical use of these extracts has been predominantly justified for a long time by the clinical evidence of efficacy and only partly by results of scientific studies. The aim of the present investigation is to perform a meta-analysis of the placebo- and verum-controlled studies carried out till now, to examine the relevance of hyperforin and hypericin for the clinical efficacy of St. John's Wort, to discuss biochemical and pharmacoendocrinological studies investigating the mechanism of action, and to describe side effects and interactions of hypericum extracts. In particular during recent years, methodologically quite sophisticated studies have been performed. The comprehensive evaluation of all studies available suggests a significant superiority of hypericum extracts over placebo, despite the negative results of two recently published American trials, and a therapeutic efficacy comparable to that of synthetic antidepressants in mildly to moderately depressed patients. Furthermore, it has been suggested in preclinical and clinical studies that the content of hyperforin but not of hypericin decisively contributes to the antidepressant efficacy of hypericum extracts. Hyperforin has been demonstrated in biochemical investigations--like synthetic antidepressants--to inhibit the reuptake of the neurotransmitters norepinephrine, serotonin, and dopamine. Hypericum extracts can be regarded as well tolerated, and they extend the variety of pharmacotherapeutical options in the treatment of depression, especially in outpatients. However, interactions in combination treatments are possible by interference with the cytochrom P450 system, thereby changing plasma levels of other medications.