Drugs that prolong QT interval: Potential pharmacologic interaction (additive effects on QT interval prolongation). Avoid concomitant use with class IA (e.g., quinidine, procainamide) or class III (e.g., amiodarone, sotalol) antiarrhythmic agents. Use with caution in patients receiving other drug that prolong the QT interval (e.g., cisapride, erythromycin, antipsychotic agents, tricyclic antidepressants).
Corticosteroids: Concomitant use of corticosteroids increases the risk of severe tendon disorders (e.g., tendinitis, tendon rupture), especially in geriatric patients older than 60 years of age.
Digoxin: No clinically important effect on pharmacokinetics of either drug. Dosage adjustment of moxifloxacin or digoxin not necessary.
Warfarin: No evidence of pharmacokinetic interactions. Careful monitoring of PT, INR, or other suitable coagulation tests in patients receiving concomitant warfarin and moxifloxacin is recommended.