May increase serum levels w/ metronidazole, NSAIDs including COX-2 inhibitors, ACE inhibitors, angiotensin II receptor antagonists, diuretics (eg, thiazide & loop diuretics), other drugs affecting electrolyte balance (eg, steroids), tetracyclines. May decrease serum levels w/ xanthines (eg, theophylline, caffeine), Na bicarbonate containing products, diuretics (eg, osmotic & carbonic anhydrase inhibitors), urea, calcitonin. May increase risk of neurotoxicity w/ antipsychotics (particularly haloperidol at higher dosages), flupentixol, diazepam, thioridazine, fluphenazine, chlorpromazine & clozapine; methyldopa; triptan derivatives &/or serotonergic antidepressants eg, SSRIs (eg, fluvoxamine & fluoxetine); Ca channel blockers; carbamazepine. Caution if co-administered w/ drugs that prolong the QT interval eg, class IA (eg, quinidine, disopyramide), class III (eg, amiodarone) antiarrhythmic agents, cisapride, antibiotics (eg, erythromycin), antipsychotics (eg, thioridazine or amisulpride). Drugs that lower epileptic threshold eg, SSRIs, TCAs, antipsychotics, anaesth, theophylline. May prolong effects of neuromuscular blocking agents. Phenytoin, indomethacin & other prostaglandin-synthetase inhibitors.