Efficacy of St. John's wort extract standardized to hyperforin
To investigate the potential role of the constituent hyperforin
in the antidepressant activity of St. John's wort (Hypericum
perforatum L., Clusiaceae), researchers compared the effects
of two different St. John's wort extracts and placebo in 147 patients
with mild or moderate depression [Laakman et al., 1998].
The two St. John's wort extracts used in the study were standardized
to either 5 percent or 0.5 percent hyperforin. Hyperforin is naturally
present in St. John's wort in larger amounts than hypericin, the
marker compound to which most St. John's wort extracts are now
standardized.
During the course of the randomized, double-blind study,
subjects received six weeks of treatment with either placebo,
the 5 percent hyperforin extract at a daily dose of 300 mg, or
the 0.5 percent hyperforin extract at a daily dose of 300 mg.
Results were assessed with the Hamilton Depression Scale (HAMD),
the Clinical Global Impression scale, and the von Zerssen Depression
Self-Rating Scale. According to the results, the 5 percent hyperforin
extract was significantly more effective than placebo in alleviating
symptoms of depression. No significant superiority over placebo
could be demonstrated with the 0.5 percent hyperforin extract.
Side effects were reported by 28.6 percent of the subjects
in each of the St. John's wort groups and by 30 percent of placebo
subjects. The most frequent adverse effect was headache, which
occurred only in the placebo group. Side effects reported by patients
taking St. John's wort included bronchitis, flu-like symptoms,
and cough.
The two St. John's wort extracts utilized in the trial were
both manufactured by Dr. Willmar Schwabe Pharmaceuticals of Germany.
The investigators concluded that the Hypericum extract
standardized to 5 percent hyperforin was "an effective option
in the treatment of mildly or moderately depressed patients, which
avoids the well-known side effects of other antidepressant agents
like tricyclics or SSRIs" as well as the abuse potential
of benzodiazepine drugs. Although it is highly unlikely that any
one compound is responsible for the antidepressant effectiveness
of St. John's wort, one laboratory study showed that hyperforin
inhibited uptake of serotonin, dopamine, noradrenaline, gamma-aminobutyric
acid (GABA), and L-glutamate [Chatterjee et al., 1998].
Evelyn Leigh, HRF
[Chatterjee SS, Bhattacharya SK, Wonnemann M, et al. Hyperforin
as a possible antidepressant component of Hypericum extracts.
Life Sciences 1998; 63(6): 499-510.
Laakmann G, Schule C, Baghai T, et al. St. John's wort
in mild to moderate depression: the relevance of hyperforin for
the clinical efficacy. Pharmacopsychiat 1998; 31(suppl):
54-59.]
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