Efficacy and safety of Vitex agnus-castus extract for treatment of premenstrual syndrome in Japanese patients: a prospective, open-label study.

Introduction: Herbal medicine containing Vitex agnus-castus (VAC) extract is widely used by women with premenstrual syndrome (PMS) in Europe, however, in Japan, clinical evidence remains to be determined. This study attempted to investigate the efficacy and safety profiles of VAC extract in Japanese patients with PMS.

Methods: A multi-center, prospective, open-label, single-arm, phase 3 study was performed in Japanese women with PMS and aged 18-44 years. The patients received Prefemin® (Max Zeller Söhne AG, Romanshorn, Switzerland), containing 20 mg of VAC extract, once daily for three menstrual cycles. The efficacy profile was examined based on the intensity of ten PMS symptoms-irritability, depressed mood, anger, headache, bloating, breast fullness, skin disorder, fatigue, drowsiness, and sleeplessness-recorded by patients via a visual analog scale (VAS). In addition, the responder rate was calculated based on the total VAS score defined by the sum of the VAS scores of the first six symptoms mentioned above. Furthermore, physician's global assessment (PGA) scores were recorded. Adverse events including vital signs and laboratory test values were monitored as safety evaluation.

Results: Sixty-nine patients received Prefemin®. After the first menstrual cycle, a statistically significant decrease in total VAS score was observed (P<0.001), and the score continued to diminish for the following two cycles. Each of the ten symptom scores decreased significantly in this manner. In addition, the responder rate increased in a time-dependent manner; the rate at the third menstrual cycle was 91.0%, and almost all of the patients were without symptoms or exhibited only mild symptoms based on PGA. Eight patients exhibited non-serious adverse events, one of which was allergic dermatitis whose causal relationship with VAC was not ruled out.

Conclusion: VAC extract improved PMS symptoms in Japanese patients, with no substantial adverse events. This is the first study to report the effect of VAC extract in Japanese patients.