Full- or half-cycle treatment of severe premenstrual syndrome with a serotonergic antidepressant

Evidence that serotonergic antidepressants are effective for treating premenstrual syndrome (PMS) raises the question of whether dosing only in the symptomatic premenstrual phase is effective for this disorder. This preliminary randomized, double-blind study compared the responses to half-cycle or full-cycle dosing of sertraline in 31 patients who completed a preceding double-blind, short-term treatment trial. The subjects fulfilled criteria for severe PMS when they entered the preceding controlled trial. At the end of the short-term treatment trial, the double-blind was not broken; both improved and unimproved subjects were randomized in a double-blind fashion to receive either full-cycle or half-cycle sertraline in the 3-month extension study. Results showed that the total premenstrual scores from the Penn Daily Symptom Report (DSR) were lower in the half-cycle dosing group in each of the 3 treatment months but did not differ with statistical significance from the full-cycle dosing group. Further analysis of the 17 DSR items showed that mood swings, nervous tension, feeling out of control, and confusion were significantly lower (p < 0.05) at endpoint in the half-cycle dosing group. Overall, subjects who improved in prior treatment remained improved; approximately half the subjects who were unimproved at entry into the extension study improved, regardless of the dosing regimen. The results add support to other preliminary reports of efficacy of serotonergic antidepressants administered premenstrually and indicate the clinical importance of determining an optimal dose/benefit ratio of serotonergic antidepressants for PMS patients.