Comparison of the serum levels in primary non-agitated depressed out-patients treated with imipramine in combination with placebo, diazepam or dixyrazine

Sixty-three non-agitated depressed out-patients were selected according to the Feighner-Robins-Guze criteria for primary depressions for a double-blind, between-patient randomized study for an 8 week duration. All the patients were treated with imipramine following a fixed dose schedule for the first 2 weeks and thereafter according to clinical response (100-200 mg/day). This treatment was combined with either placebo, diazepam (10 mg/day) or dixyrazine (50 mg/day). The serum concentration of imipramine both at 2 weeks and later was significantly higher (P less than 0.05) in the group treated with dixyrazine than in the other two groups. In the group treated with diazepam, the serum levels of imipramine and desipramine were significantly lower than in the placebo group. The serum concentrations of diazepam, desmethyldiazepam and dixyrazine were almost unchanged during the study. No significant correlation was found between the dosage and the serum concentration of imipramine or desipramine. The change in mean CPRS-score correlated neither with the imipramine nor with the desipramine serum levels, it did correlate but negatively with the degree of side effects. The degree of side effects correlated positively with the serum concentration of desipramine.