Spectrofluorimetric determination of fluvoxamine in dosage forms and plasma via derivatization with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole.

A highly sensitive and simple spectrofluorimetric method has been developed and validated for the determination of the antidepressant fluvoxamine (FXM) in its dosage forms and plasma. The method was based on nucleophilic substitution reaction of FXM with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in an alkaline medium (pH 8) to form a highly fluorescent derivative that was measured at 535 nm after excitation at 470 nm. The factors affecting the reaction was carefully studied and optimized. The kinetics of the reaction was investigated, and the reaction mechanism was presented. Under the optimized conditions, linear relationship with good correlation coefficient (0.9995) was found between the fluorescence intensity and FXM concentration in the range of 65-800 ng ml(-1). The limits of detection and quantitation for the method were 21 and 64 ng ml(-1), respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 2.17%. The proposed method was successfully applied to the determination of FXM in its pharmaceutical tablets with good accuracy; the recovery values were 97.8-101.4 +/- 1.08-2.75%. The results obtained by the proposed method were comparable with those obtained by the official method. The high sensitivity of the method allowed its successful application to the analysis of FXM in spiked human plasma. The proposed method is superior to the previously reported spectrofluorimetric method for determination of FXM in terms of its simplicity. The proposed method is practical and valuable for its routine application in quality control and clinical laboratories for analysis of FXM.