The effectiveness of mirtazapine in the treatment of post-traumatic stress disorder: A 24-week continuation therapy

Few studies for the long-term effects of antidepressants on post-traumatic stress disorder (PTSD) have been conducted. The aim of the present study was to investigate the effectiveness of mirtazapine during the 24-week continuation treatment in patients with PTSD. Out of 15 patients who participated in the previous 8-week short-term study, 12 patients completed 24-week continuation treatment with mirtazapine. The effectiveness was evaluated at week 12 and week 24 using Impact of Event Scale-Revised (IES-R), Short PTSD Rating Interview (SPRINT), Interviewer-Administered Structured Interview for PTSD (SIP) and Montgomery-Àsberg Depression Rating Scale (MADRS). The tolerability of continuation treatment was also reported. The scores on the IES-R, SPRINT, SIP and MADRS were significantly reduced over time from baseline to week 24, the end-point (F= 36.1, d.f. = 4, P < 0.001; F =106.3, d.f. = 4, P < 0.001; F =121.1, d.f. = 4, P < 0.001; F =198.9, d.f. = 4, P < 0.001). On post-hoc analysis, the scores of all four measures were significantly reduced at the end point since week 8. However, after Bonferroni's correction, that was statistically significant in SPRINT only. The number of patients whose scores were reduced over 50% in all four scales had a tendency of incremental increase from three at week 8 to eight at the end point (P = 0.063). No serious drug-related side-effects occurred. These results suggest that the mirtazapine may be effective in the continuation treatment of PTSD as well as short-term treatment. Further and better-designed studies are necessary.