Background and objective: Prulifloxacin, a broad-spectrum fluoroquinolone, is quantitatively transformed after oral administration into ulifloxacin, the active metabolite. On the basis of preclinical data suggesting that prulifloxacin is not likely to prolong the QT interval, a trial to assess the potential effects of prulifloxacin on QT and corrected QT (QTc) interval in humans was performed.
Methods: Fifty-two healthy subjects were randomized into three groups to receive prulifloxacin 600 mg, moxifloxacin 400mg and placebo once daily for 5 days, using a crossover, double-blind versus placebo, moxifloxacin-controlled study. At baseline and days 1 and 5, three 12-lead digital ECGs were recorded before and up to 24 hours after dosing at nine predefined timepoints. Blood samples were also collected at each treatment timepoint. ECG data were analysed in a blinded manner by a centralized laboratory using skilled readers. QT values were corrected for heart rate using an individual correction method (QTcI) as the primary variable, and Fridericia's method as reference.
Results: In forty-eight subjects who completed the study, compared with placebo, prulifloxacin had no relevant effect on cardiac repolarization, with the largest mean QTcI increase being 3.97 ms (one-sided 95% CI 0.01, 7.93), whereas moxifloxacin demonstrated the expected positive effect (maximum mean QTcI increase of 12.0 ms, one-sided 95% CI 8.66, 15.34), thus demonstrating the good sensitivity of the study. A statistically significant correlation between QTcI changes and plasma concentrations was found for moxifloxacin but not for ulifloxacin.
Conclusion: Prulifloxacin at steady state after therapeutic doses has no significant effects on the QTc interval and thus should prove to have no cardiac liability.