Pharmacodynamic properties of St. John's wort-A single blind neurophysiological study in healthy subjects comparing two commercial preparations.

In this clinical trial the effects on the central nervous system (CNS) of two commercially available extracts of St. John's wort (Texx 300 and Jarsin 300) were compared with those of placebo in a group of healthy young volunteers (n = 35) following a single blind study design. Measurements were carried out on the first day and after repetitive drug application (t.i.d.) over 3 weeks. In accordance to the known slow resorption of hypericum extracts maximum effects were observed for both preparations between 4 and 6 h after intake. Texx 300 produced alpha2 increases of up to 32% in comparison to placebo. Somewhat weaker increases were observed after Texx 300 within the beta frequencies (14% resp. 15%) and in alpha1 band (8%). Jarsin 300 produced less power increases within the alpha2 range. In addition beta increases were observed after Jarsin 300 following repetitive administration. Thus slight differences could be detected between the two preparations with respect to their maximum effects, but in general the profile of action was similar for both drugs becoming more clear after the repetitive dosing. However, the effects of Texx 300 occurred a little bit earlier possibly due to a better intestinal resorption. Concerning the auditory event related potentials both preparations tended to decrease the latency of the cognitive potential P 300 indicating an improvement of mental performance. The observed neurophysiological changes are in line with the proposed clinical efficacy of both plant extracts, especially with respect to the drug induced changes within the alpha1 and alpha2 frequency ranges known for being under serotonergic and dopaminergic control, respectively. These electrochemical features of brain activity are known to be of great importance during the course of action of antidepressive drugs. - In summary quantitative EEG proved to be able to discriminate between different extracts of St. John's wort with respect to time of effect and profile changes on neuronal communication structure.

RCT Entities:   Population Interventions Outcomes