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Fluoxetine is a nontricyclic antidepressant which blocks serotonin reuptake selectively. Its N-demethyl metabolite, norfluoxetine is also selective inhibitor of serotonin uptake . This study was carried out to compare the bioavailability of Myung-in fluoxetine (20mg/cap.) with that of Prozac(R). The bioavailability was conducted on 24 healthy volunteers who received a single dose (80mg) of each drug in the fasting state, in a randomized balanced 2-way crossover design. After closing, serial blood samples were collected for a period of 48 hours, Plasma was analyzed for fluoxetine and norfluoxetine by a sensitive and validated HPLC assay. The major pharmacokinetic parameters (AUC0-48 hr, Cmax, Tmax , AUCinf., MRT. T1/2, Vd and Cl) were, calculated from the plasma fluoxetine concentration-time data of each volunteer. The microcomputer program, `WinNonlin` was used for compartmental analysis. A two-compartment model with first-order input, first-order output and no lag time was chosen as the most appropriate pharmacokinetic model. The data were best described by using a weighting factor of l/y2. Though the plasma fluoxetine concentrations of Myung-in fluoxetine were higher than those of Prozac(R) at all observed time from 7.9% to 16.9% (P<0.05 at 6.7 and 10 hr), the bioavailability of Myung-in fluoxetine appeared to be bioequivalent with that of Prozac(R). There were no statistical significant differences between the two drugs in all pharmacokinetic parameters including AUC0-48 hr of norfluoxetine.
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