Melatonin and pro-hypnotic effectiveness of the antidepressant Trazodone: A preliminary evaluation in insomniac mood-disorder patients

Objective To preliminary investigate the link between the darkness hormone melatonin (MLT) and the pro-hypnotic effectiveness of the atypical antidepressant Trazodone (TRZ) in a group of mood disorder patients suffering of insomnia. Design and methods The study's design comprised: i) the enrolment of insomniac outpatients, ii) baseline (t0) psychiatric and biochemical examinations; iii) the subsequent patients' introduction into a treatment with TRZ for 3–4 weeks, followed by post-therapy re-evaluations (t1). The MLT function was investigated by t0/t1 ELISA determinations of 6-hydroxy-MLT sulfate (6-OH-MLTs) levels in early-morning urines and HPLC analysis of morning MLT serum amount. Concomitantly, TRZ and its metabolite m-chloro-phenylpiperazine (m-CPP) were measured by HPLC in serum to monitor patients' compliance/metabolism. Results Seventeen insomniac outpatients, displaying mild symptoms of depression/anxiety resistant to antidepressants, completed TRZ therapy (dose:10–20 mg/day, bedtime). Serum TRZ levels (127 ± 57 ng ml− 1, mean ± SD) confirmed patients' compliance, while the anxiogenic metabolite m-CPP resulting almost undetectable. Moreover, the 6-OH-MLTs output was found increased at t1 vs. baseline values (t1: 58.4 ± 45.02 ng ml− 1; t0: 28.6 ± 15.8 ng ml− 1; mean ± SD, P < 0.05) in 9 patients who recovered both insomnia and depression/anxiety (P < 0.01). Unresponsive subjects showed instead no post-therapy 6-OH-MLTs variation (t1: 48.53 ± 50.70 ng ml− 1; t0: 49.80 ± 66.53 ng ml− 1). Morning MLT in serum slightly diminished at t1 without reaching the statistical significance, not allowing therefore to define the patients' outcome. Conclusions This initial investigation encourages to explore MLT networks as possible correlates of TRZ pro-hypnotic responses.