Effects of moxifloxacin on QT interval in conscious dogs

Area of Science:

• Pharmacology
• Cardiovascular Science
• Veterinary Medicine

Background:

• Moxifloxacin is known to cause QT prolongation in preclinical and clinical settings.
• Previous studies have not confirmed this effect in conscious dogs at clinically relevant concentrations.

Purpose of the Study:

• To investigate the effects of moxifloxacin on the QT interval in conscious, healthy dogs.
• To determine if QT prolongation occurs at clinically relevant plasma concentrations.

Main Methods:

• Four healthy dogs were instrumented to monitor cardiovascular parameters and electrocardiograms (ECGs).
• Moxifloxacin was administered intravenously in escalating doses (0, 1, 10, 25, 50 mg/kg).
• QT and QTc intervals were analyzed in relation to drug concentration.

Main Results:

• Moxifloxacin caused a dose-dependent increase in QT interval at 10, 25, and 50 mg/kg.
• QTc prolongation was observed at 25 and 50 mg/kg.
• Statistically significant increases in arterial blood pressure were noted at 50 mg/kg.
• These effects were observed at clinically relevant plasma concentrations.

Conclusions:

• Moxifloxacin induces QT and QTc prolongation in conscious dogs at clinically relevant concentrations.
• The study design with four dogs was sufficiently sensitive to detect these effects.
• This provides further evidence of moxifloxacin's cardiotoxic potential.