The usefulness of monitored therapy using Clozapine concentration in the blood serum for determining drug dose in Polish schizophrenic patients

BackgroundThe aim of the study is to evaluate the advisability of systematic monitoring of clozapine (CLO) concentration in serum during treatment of schizophrenia in Polish psychiatric patients.MethodThe concentration of CLO and its metabolites: norclozapine (NCLO) and clozapine N-oxide (CLO-NO) in serum obtained from 107 patients suffering from schizophrenia was determined by high performance liquid chromatography (HPLC) method. There were two groups of patients. In the first group of patients (n = 95) the concentration of drug and its metabolites was determined by one-time testing. Correlations were tested using the test statistics. In the second group of patients (n = 12), 51 samples of serum were provided by the same patient in different time spans (from 6 days to 14 months after the beginning of the treatment).ResultsConcentrations of CLO and its metabolites in blood serum do not always show a linear dependence on the applied dose for individual patients.ConclusionThe high volatility of CLO concentrations in blood serum of patients treated with identical doses of the drug confirmed the validity of the monitored therapy.