Chlorphen - Ear Drops Chloramphenicol 5% + Lidocaine Hydrochloride 1% Ear drops - 500mg+100mg/100ml 1 10ml drop(s) / 10ml drop Nipa Pharmaceuticals Ltd. Indication: Acute bacterial ear infections Adult Dose: Otic/Aural Otitis externa Adult: Instill 2-3 drops into the ear bid-tid. Contraindication: History of hypersensitivity or toxic reaction to the drug; Perforated ear drum. Herpes simplex and other virul conditions of the eye or ear, mycosis. Mode of Action: Chloramphenicol inhibits bacterial protein synthesis by binding to 50s subunit of the bacterial ribosome, thus preventing peptide bond formation by peptidyl transferase. It has both bacteriostatic and bactericidal action against H. influenzae, N. meningitidis and S. pneumoniae. Lidocaine is an amide type local anaesth. It stabilises the neuronal membrane and inhibits Na ion movements, which are necessary for conduction of impulses. In the heart, lidocaine reduces depolarisation of the ventricles during diastole and automaticity in the His-Purkinje system. Duration of action potential and effective refractory period are also reduced. Precaution: Avoid prolonged use. Discontinue immediately if local hypersensitivity reactions occur. Side Effect: Ear drops: Ototoxicity. Interaction: Decreased effects of iron and vitamin B12 in anaemic patients. Phenobarbitone and rifampin reduce efficacy of chloramphenicol. Impairs the action of oral contraceptives. Potentially Fatal: Increases the effect of oral anticoagulants, oral hypoglycaemic agents, phenytoin. Avoid concomitant administration with drugs that depress bone marrow function. May increase serum levels w/ cimetidine and propranolol. Increased risk of cardiac depression w/ ?-blockers and other antiarrhythmics. Additive cardiac effects w/ IV phenytoin. Hypokalaemia caused by acetazolamide, loop diuretics and thiazides may antagonise effect of lidocaine. Dose requirements may be increased w/ long-term use of phenytoin and other enzyme-inducers.