Determination of trazodone and its metabolite, 1-m-chlorophenyl- piperazine, in human plasma and red blood cell samples by HPLC

Objectives: To develop an HPLC method for the analysis of trazodone and its metabolite, 1-m-chlorophenyl-piperazine (m-CPP), in human plasma and red blood cells. Design and Methods: The analytes were extracted by heptane containing 1.5% isoamyl alcohol, back extracted into phosphoric acid and analyzed by reverse phase HPLC with UV detection. Results: In seven randomly selected, male, human subjects plasma concentrations (nmol/l) were 380-5841 for trazodone and 14-237 for rn-CPP while those in packed red blood cells were 98-634 for trazodone and 15-155 for m-CPP. Plasma trazodone concentrations were 4-11-fold higher than those in red blood cells while those of m-CPP were about equal. This may be the first report on concentrations of trazodone and m-CPP in human red blood cells. Conclusions: This sensitive method can be used for monitoring trazodone and m-CPP in human plasma and red blood cells.