016: Comparative Pharmacokinetics & Bioequivalence Study of Gatifloxacin 200mg Tablets

Statement of Purpose, Innovation or Hypothesis: This pharmacokinetic study aimed to determine various parameters of the newly marketed cost-effective Gatifloxacin 200mg (Test) tablet and establish its bioequivalence against the reference formulation (Std).

Description of Methods & Materials: Twelve healthy non-smoker male subjects underwent a randomized, single-dose, open-label, two-sequence, two-treatment crossover design, with a 2-week washout period. Blood samples (5mL) were withdrawn at specified intervals, and plasma drug concentrations were determined using a validated HPLC method following FDA guidelines. The method showed linearity in the range of 0.03 – 20 µg/ml, with a coefficient of correlation (r²) of 0.998. Chromatographic separation was achieved using a LC-10 AT VP pump, SPD-10 AVP UV/visible detector, and a Bondapak C18 column with a mobile phase of 80% NaH2PO4 buffer solution and 20% acetonitrile (pH = 3) at a flow rate of 1ml/min. Inter and intraday accuracy ranged from 98.0% to 100%, with lower limits of quantification and detection of 4.8ng/ml and 1.2ng/ml, respectively.

Data & Results: Pharmacokinetic parameters were calculated using Phoenix WinNonlin 6.4 software. The mean C_>max values for Std and Test were 2.25 ± 0.01 and 2.32 ± 0.10 µg/ml, respectively, with T_max values of 1.04hr ± 0.09 and 0.99hr ± 0.12. AUC0_-t and AUC0_-∞ were estimated as 15.47 ± 1.18 mg/L.hr and 14.38 ± 1.38 mg/L.hr for Std, and 14.539 ± 1.571 mg/L.hr and 15.109 ± 1.776 mg/L.hr for Test. Statistical analysis using ANOVA and two one-sided t-tests showed no significant differences in C_max, T_max, AUC0_-t, and AUC0-_∞ between the formulations. The 90% confidence intervals (80-125) on log-transformed data fell within 97.2 - 100.2%, 98.4 - 100.7%, 81.2 – 96.3%, and 88.8 - 100.2% for these parameters, with geometric mean ratios of 99.9, 102.7, 88.4, and 95.4, respectively. Furthermore, non-log-transformed data confirmed equivalence between the products.

Interpretation, Conclusion or Significance: Based on C_max, T_max, AUC0-_t and AUC0-_∞, the Std and Test were deemed bioequivalent according to FDA criteria.