Mianserin plasma levels and differential clinical response in endogenous and reactive depression

Fifty patients with moderate to severe primary depression were treated in equal groups of inpatients and outpatients with a constant dose of 60 mg. of mianserin daily for four weeks in a double blind placebo controlled trial with either a three times daily dosage regime or a single nightly dose. There was no difference in apparent compliance, side effects or therapeutic effect in either day-time or night-time dosage regimes. Patients developing high plasma levels of mianserin (greater than 70 microgram/l) were associated with a highly significantly poorer therapeutic outcome. Patients identified as endogenous depression demonstrated a significant negative correlation between plasma levels of mianserin and therapeutic response measured as an amelioration of either the Hamilton Rating Scale scores (r = --0.48) or on a new depression scale by Montgomery and Asberg (r = --0.51) with high levels associated with poor response. There was a significant correlation (r = 0.66) between mianserin plasma levels and age in endogenous depression. In those patients identified as suffering from reactive depression, no significant relationship could be seen between plasma levels and therapeutic response or with age. These findings support the view that the relationship between mianserin plasma levels and clinical response is more likely to be demonstrated in endogenous depression.