Relationship between mianserin plasma levels and antidepressant effect in a double-blind trial comparing a single...

1. Twenty-six in-patients and 24 out-patients suffering from moderate or severe primary depressive illness were randomly allocated to either a single night-time dose of mianserin 60 mg or a three times daily regimen in a double-blind controlled trial. 2. There was no significant difference in antidepressant effect between the two dosage regimens in either patient group measured using Hamilton Rating Scale (HRS), the Beck Self-Rating Inventory (BSRI) and the new Montgomery and Asberg Depression Scale (MADS). 3. A significant negative correlation (-0.36 P less than 0.05) was found between plasma levels and clinical response using the MADS. A trend for patients with low levels to do worse was also observed suggesting a curvilinear relationship. A highly significant poorer clinical response in patients with levels above 70 microgram/1 was observed using the MADS (t = 3.33, P less than 0.005). This was also seen with the HRS (t = 2.42, P less than 0.02). 4. A significant correlation (r = 0.29, P less than 0.05) with age is reported, and a highly significant increased variability (F = 7.07, P less than 0.001) of mianserin plasma levels in patients over 55 was demonstrated.