Abstract
Fluoxetine (FLX) is a highly selective serotonin reuptake inhibitor used as an antidepressant agent and administered as the racemate. In this study, we developed an isocratic HPLC method with fluorescence detection for the determination of FLX enantiomers ((R)-FLX and (S)-FLX) in human serum and urine, after pre-column derivatization with (R)-(+)-4-nitro-7-(2-chloroformyl- pyrrolidin-1-yl)-2,1,3-benzoxadiazole ((R)-(+)-NBD-Pro-COCl). After basic extraction of the samples into pentane, derivatization with (R)-(+)-NBD-Pro-COCl was conducted in borate buffer (pH 9.0) at 70°C for 5 min. Protriptyline was utilized as an internal standard. The regression equations for (R)-FLX hydrochloride and (S)-FLX hydrochloride in human serum showed good linearity in the range of 0.01–0.5 μg/mL with the detection limit of 0.005 μg/mL and in the range of 0.025–0.5 μg/mL with the detection limit of 0.008 μg/mL, respectively. The corresponding values for human urine were 0.025–0.5 μg/mL with the detection limit of 0.014 μg/mL and 0.025–0.5 μg/mL with the detection limit of 0.010 μg/mL, respectively. The coefficients of variation were less than 11.8%, and recovery was good. Our method using (R)-(+)-NBD-Pro-COCl is useful for simultaneous determination of (R)-FLX and (S)-FLX in human serum and urine, and may be suitable for therapeutic drug monitoring.