Pharmacological Toxicological Effects 51 Prolactin Secretion

Evidence of varying levels of discrimination exists that demonstrate V. agnus-castus inhibits the secretion of prolactin by the pituitary gland. In a randomized, placebo-controlled, double-blind study, Milewicz et al. examined whether V. agnus-castus affected elevated pituitary prolactin reserve. Participants were 52 women with luteal phase defects caused by latent hyperprolactinemia. Intervention was V. agnus-castus 20 mg daily or placebo, for 3 months. Only 37 women (20 = placebo, 17 = V. agnus-castus) completed the study. Outcome measures were pre- and posthormonal analysis (blood draws taken on days 5-8 and day 20 of menstrual cycle) 1 month prior to treatment and after 3 months of treatment and latent hyperpro-lactinemia analysis (monitoring prolactin release 15 and 30 minutes after intravenous injection of 200 ^g thyrotropin-releasing hormone (TRH). Results from this study showed that compared to preintervention, the V. agnus-castus group had statistically significant reduced prolactin release after 3 months, whereas the control group did not. The study's information came from an English abstract of a German publication. Information about inclusion/exclusion criteria, study specifics, study funding, or author disclosures were not available (25).

In an open and intraindividual comparison study, Merz et al. conducted a clinical study of tolerance and prolactin secretion of V. agnus-castus using 20 healthy male subjects between the ages of 18 and 40 years. Placebo and three doses of V. agnus-castus (total daily dosages of 120, 240, and 480 mg were divided into 8-hour administration times) were given in an increasing sequence. Prolactin concentration profile after TRH stimulation was assessed by determining the maximum concentrations (cmax) and the area under the curve over a period of one hour (AUC0-1h). These procedures were identical in all four study phases. Results for the AUC0-24h showed that as daily doses increased, prolactin levels decreased ([AUC0-24h. {^IU ■ hour}/^A ± standard deviation]; placebo: 6182 ± 1827; 120 mg: 6874 ± 1790; 240 mg: 5750 ± 1594; 480 mg: 5998 ± 1664), with statistically significant findings for the 120-mg dosage only (26).

Wuttke reported in a 1996 abstract the results of experiments demonstrating that 3 months of V. agnus-castus therapy (double-blind clinical study vs placebo) significantly reduced basal prolactin levels in patients. However, details of the experiments and study subjects were not outlined or referenced (17).

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