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Objective: The purpose of this randomized, crossover study was to compare the bioavailability of a generic and innovator formulation of gatifloxacin 400 mg tablets under fasting conditions.Methods: Seventeen blood samples per period were collected from 24 healthy, Arab male volunteers over 36 hours, plasma gatifloxacin concentrations were determined by HPLC assay, and pharmacokinetic parameters were deter-mined by the non-compartmental method.Results: Mean +/- SD C[max], T[max], AUC[for symbol see text] AUC[for symbol see t4st], and t[1/2]] were 4.88 +/- 1.02 and 4.88 +/- 0.99 microg/mL, 1.19 +/- 0.62 and 1.14 +/- 0.79h, 37.81 +/- 5.54 and 39.12 +/- 5.19 microg.h/mL, 39.68 +/- 5.86 and 38.00 +/- 5.43 microg.h/mL, and 8.07 +/- 0.62 and 8.08 +/- 0.75 h for the generic and innovator formulation, respectively. ANOVA revealed significant formulation effect for AUC[for symbol see text] and AUC[for symbol see text]. However, the parametric 90% confidence intervals on the mean of the difference between log-transformed values were within the bioequivalence accepted range of 80 to 125%, namely: 102.06% to 107.34%,101.69% to 107.10%, and 94.00% to 106.10%, for AUC [for symbol see text], AUC [for symbol see text], and C[max], respectively.Conclusion: The results indicate that the two formulations are both statistically different and equivalent, in the rate and extent of absorption. This may be due to a large sample size in relation to sample variance. [ABSTRACT FROM AUTHOR]

A simple reversed-phase high performance liquid chromatography (HPLC) method for the determination of gatifloxacin stability in human plasma was developed and validated. Using ciprofloxacin as an internal standard (IS), separation was achieved on X Terra MS C18 (3 mm x 50 mm, 5 microm) column. The mobile phase, 0.025 M disodium hydrogen phosphate (pH 3.0) and acetonitrile (80:20 v/v), were delivered at a flow rate of 1.0 ml/min. The eluent was monitored using spectrophotometeric detection at 293 nm. Plasma samples were deproteinized using Amicon Centrifree system. No interference in blank plasma or of commonly used drugs was observed. The relationship between gatifloxacin concentration and peak height ratio of gatifloxacin to the IS was linear over the range of 0.10-6.0 microg/ml. The intra-day and inter-day coefficients of variation were < or = 2.77 and < or = 4.59%, respectively. The extraction recovery of gatifloxacin and the IS from plasma samples was > or = 85%. Gatifloxacin was found to be stable for at least 5 h at RT, 7 weeks at -20 degrees C, and after 3 freeze-thaw cycles in plasma; 16 h at RT and 48 h at -20 degrees C in deproteinized plasma; and 24 h at RT and 7 weeks at -20 degrees C in phosphate buffer.

An expedient high-performance liquid chromatography (HPLC) assay for nizatidine measurement in human plasma was developed and validated. After deproteinization of 200 microL of plasma by filtration, nizatidine and 4-amino-antipyrine (internal standard) were separated (capacity ratio 3.0 and 6.63, respectively) on Nova-Pak C18 cartridge at room temperature (RT), and detected spectrophotometrically at 320 nm. The mobile phase, 0.02 mol/L disodium hydrogen phosphate, acetonitrile, methanol, and triethylamine (80:10:10:0.05 vol/vol), was delivered at 1.5 mL/min. Calibration curves were linear (r2 > or = 0.999) in the range 0.02 to 5 microg/mL, detection and quantification limits were 0.01 and 0.02 microg/mL, respectively, intra-run and inter-run coefficients of variation were < or = 3.5% and < or = 4.2%, respectively, and recovery was >90%. Nizatidine was stable for at least 4 hours at RT, 12 weeks at -20 degrees C, and 3 freeze-thaw cycles in plasma; 16 hours at RT and 48 hours at -20 degrees C in deproteinized plasma; and 6 hours at RT and 3 weeks at -20 degrees C in water.

Purpose: The purpose of this randomized, crossover study was to compare the bioavailability of a generic and an innovator formulation of nizatidine 300 mg capsules under fasting conditions., Methods: Twenty blood samples per period were collected from 20 healthy, Arab male volunteers over 16 h, plasma nizatidine concentrations were determined by HPLC assay, and pharmacokinetic parameters were determined by the non-compartmental method., Results: Mean+/-SD C(max), T(max), AUC(0-->t), AUC(0-->infinity), and t1/2 were 2.96+/-0.54 and 3.28+/-0.68 microg/ml, 1.31+/-0.70 and 0.93+/-0.38 h, 9.04+/-1.66 and 9.03+/-1.94 microg x h/ml, 9.17+/-1.64 and 9.12+/-1.94 microg x h/ml, and 1.64+/-0.21 and 1.58+/-0.22 h for the generic and innovator formulation, respectively. The parametric 90% confidence intervals on the mean of the difference between log-transformed values were 98.06% to 103.21%, 98.74% to 103.71%, and 83.37% to 101.34%, for AUC(0-->t), AUC(0-->infinity), and C(max), respectively., Conclusion: The results indicate that these two formulations are equivalent in the rate and extent of absorption., (Copyright 2005 John Wiley & Sons, Ltd.)