Hypersensitivity; anaphylaxis, severe cutaneous ARs (SCARs) including SJS, TEN, DRESS & acute generalized exanthematous pustulosis. Congenital or documented QT interval prolongation, electrolyte disturbances, clinically relevant bradycardia, cardiac arrhythmia or insufficiency. Observe for signs of superinfection w/ non-susceptible organisms eg, fungi. Not to be co-administered w/ ergot derivatives. Concurrent use w/ QT interval prolonging substances eg, class IA & III antiarrhythmics, antipsychotics, antidepressants, fluoroquinolones. Significant hepatic disease. Severe renal impairment. Pregnancy & lactation. Infantile hypertrophic pyloric stenosis. Elderly.