THE INFLUENCE OF LITHIUM ON FLUVOXAMINE THERAPEUTIC EFFICACY AND PHARMACOKINETICS IN DEPRESSED-PATIENTS ON COMBINED FLUVOXAMINE-LITHIUM THERAPY

The influence of lithium on fluvoxamine therapeutic efficacy, plasma c oncentrations and pharmacokinetics was studied in 12 depressed inpatie nts. Six patients were on fluvoxamine monotherapy and six were on comb ined fluvoxamine-lithium therapy. The treatment response was determine d using 17-item Hamilton Rating Scale for Depression. Blood samples we re collected during 48 h after a single dose administration of 100 mg fluvoxamine, and five times at steady state after repeated doses of 10 0 mg fluvoxamine per day. The evaluation of 17-item Hamilton Rating Sc ale for Depression Scores showed a significant clinical improvement 2 and 4 weeks after the beginning of the therapy in both groups (p < 0.0 1). However, 2 weeks after the administration of the drug(s) had start ed, significant differences (p < 0.05) in efficacy between the two tre atments in favour of the fluvoxamine-lithium combination were found. P lasma concentrations of fluvoxamine were measured by high-performance liquid chromatography. The comparison of the measured concentrations o f fluvoxamine showed a similar course of the plasma concentration-time curves in both groups of patients. Pharmacokinetic parameters of fluv oxamine did not show any significant difference on the comparison betw een the groups. According to the results from this study, it is eviden t that lithium does not affect plasma concentrations and pharmacokinet ics of fluvoxamine in depressed patients on concomitant treatment with these two drugs. However, the effect achieved with the combination wa s better.