CORRELATION BETWEEN STEADY-STATE PLASMA-CONCENTRATIONS OF MIANSERIN AND TRAZODONE IN DEPRESSED-PATIENTS

Objective: The correlations between steady-state plasma concentrations of mianserin and its active metabolite desmethylmianserin and those o f trazodone and its active metabolite m-chlorophenylpiperazine (m-CPP) were examined in 19 depressed patients. Methods: Ten patients receive d first mianserin (30 mg per day) and second trazodone (150 mg per day ), while 9 patients received these treatments in the opposite sequence , with at least 2-week intervals between the two phases. Blood was sam pled at steady state, 1-3 weeks after initiation of each treatment. Pl asma concentrations of mianserin, the separate enantiomers S(+)- and R (-)-mianserin, desmethylmianserin, trazodone and m-CPP were measured b y means of high-performance liquid chromatography. Results: There was a significant correlation between steady-state plasma concentrations o f trazodone and total mianserin (r = 0.59) or S(+)-mianserin (r = 0.57 ), but not R(-)-mianserin (r = 0.33). Conclusion: The present study th us suggests that the metabolic capacity of mianserin, especially the m ore active S(+)-enantiomer, and that of trazodone correlate to each ot her. This finding supports the previous suggestions that cytochrome P4 502D6 is involved in the metabolism of mianserin and trazodone.