Increased CNS & resp depression & hypotensive effect w/ alcohol, CNS depressants. Increased risk of resp depression, profound sedation, coma w/ benzodiazepines. Serotonin syndrome w/ serotonergic drugs. Incompatibility w/ barbiturate salts, aminophylline, amobarbital, floxacillin, furosemide, amylobarbitone Na, ephedrine sulphate, heparin Na, hydrocortisone Na succinate, methicillin Na, methylprednisolone Na succinate, morphine sulphate, nitrofurantoin Na, pentobarbitone Na, phenobarb Na, phenytoin Na, oxytetracycline HCl, thiamylal Na, thiopental Na, Na bicarbonate, sulphadiazine Na, Na iodide, sulphafurazole diethanolamine or thiopentone Na, acyclovir Na, imipenem, frusemide, idarubicin, allopurinol, amphotericin B cholesteryl sulphate complex, cefepime; K iodide-, aminosalicyclic acid- & salicylamide-containing soln. Colour changes or precipitation w/ minocycline HCl, tetracycline HCl, cefoperazone Na, mezlocillin Na, nafcillin Na, liposomal doxorubicin HCl.