Abstract Fluoroquinolones, despite their use as antibiotics of choice in the treatment of several microbial infections have been associated with the risk of the development of Torsades de pointes (Tdp). This study was conducted to evaluate the comparative effect 2 fluoroquinolone antibiotics, Ciprofloxacin and Levofloxacin, orally administered over a period of 14 days on QT and QTc interval.
In a cross over study, 8 apparently healthy male dogs were equally and randomly divided into 2 groups. Ciprofloxacin and Levofloxacin were orally administered respectively to each group at the dosage of 25mg/kg weight twice daily for a period of 14 days. Electrocardiographic readings were taken 30 minutes before administration and subsequently on days 2, 5, 7, 10 and 14 post-treatment. Lead II QT readings were measured and compared with pre-administration values. For each QT reading, QTc (Bazett) and QTc (Fridericia) values were calculated. Data were analysed using one-way ANOVA with the Tukey post-hoc analysis at a 5% level of significance.
For each of the treatment groups, no significant differences (p>0.05) were observed for the heart rate, QT, QTc (Bazett) and QTc (Fridericia) in the dogs when compared with pre-administration values. From this study, neither Ciprofloxacin nor Levofloxacin appeared to have a significant effect on QT and QTc values measured. At the dosage administered, the drugs did not show any observable risk for the manifestation of TdP.