Other xanthines. Clearance reduced by allopurinol, some antiarrhythmics, cimetidine, disulfiram, fluvoxamine, interferon-alpha, macrolide antibiotics, quinolones, oral contraceptives, thiabendazole and viloxazine. Clearance increased by phenytoin, anticonvulsants, ritonavir, rifampicin, sulfinpyrazone, cigarette smoking. Corticosteroids, diuretics, beta2-agonists.
Potentially Fatal: Increased risk of cardiac arrhythmias with sympathomimetics and halothane. Tachycardia with pancuronium. beta-blockers inhibit metabolism. Increased risk of convulsion with quinolones, ketamine.