Enhanced toxicity w/ cimetidine, propranolol. Depressed microsomial activity w/ cimetidine. Reduced clearance w/ ranitidine. Increased serum levels w/ antiviral agents eg, amprenavir, atazanavir, darunavir, lopinavir. Antagonized action w/ diuretics. Additive systemic toxic effects w/ other local anaesth or drugs structurally related to amide-type local anaesth eg, antiarrhythmics (ie, mexiletine). Increased risk of ventricular arrhythmia w/ antipsychotics prolonging QT interval (eg, pimozide, sertindole, olanzapine, quetiapine, zotepine), prenylamine, adrenaline or 5-HT
3 antagonists (eg, tropisetron, dolasetron); quinupristin/dalfopristin. Increased risk of enhanced & prolonged neuromuscular blockade w/ muscle relaxants eg, suxamethonium. CV collapse w/ bupivacaine in patients on treatment w/ verapamil & timolol. Reduced convulsant threshold by dopamine, 5-hydroxytryptamine; narcotics. Reduced convulsant threshold & increased CNS depressant effect by opioid-antiemetic combination. Decreased vascular absorption, increased danger of ventricular tachycardia & fibrillation w/ adrenaline. Incompatibility w/ amphotericin, methohexitone, glyceryl trinitrate. Class III anti-arrhythmics eg, amiodarone.