Xylocaine Injection Drug Interactions

Antiarrhythmic Drugs: Local anaesthetics of the amide-type eg, lignocaine, should be used with caution in patients receiving other local anaesthetics or agents structurally related to amide-type local anaesthetics eg, certain antiarrhythmic drugs eg, disopyramide, procainamide, mexiletine since potentiation of cardiac effects may occur. Specific interaction studies with lignocaine and antiarrhythmic drugs class III (eg, amiodarone) have not been performed, but caution should be advised (see Precautions).
Amiodarone: Amiodarone has been reported to reduce the clearance of lignocaine in 2 case reports, although a small prospective study of combined therapy on lignocaine pharmacokinetics found no change in clearance or other pharmacokinetic factor. This combination has been reported to precipitate seizures and to lead to severe sinus bradycardia and a long sinoatrial arrest. Until more experience with concurrent use of lignocaine and amiodarone becomes available, patients receiving the combination should be monitored carefully.
Beta-Adrenoreceptor Antagonists: Propranolol and metoprolol reduce the metabolism of IV administered lignocaine and the possibility of this effect with other β-adrenergic blockers should be kept in mind. If these drugs are administered concurrently, the patient should be closely observed for signs of lignocaine toxicity.
Cimetidine: Cimetidine reduces the clearance of IV administered lignocaine and toxic effects due to high serum lignocaine levels have been reported when these 2 drugs have been administered concurrently.
Anticonvulsive Agents: Phenytoin and other antiepileptic drugs eg, phenobarbitone, primidone and carbamazepine appear to enhance the metabolism of lignocaine but the significance of this effect is not known. Phenytoin and lignocaine have additive cardiac depressant effects.
Inhalational Anaesthetics: Lignocaine decreases the minimum effective concentration of inhalational anaesthetics eg, nitrous oxide.
Skeletal Muscle Relaxants: Lignocaine and skeletal muscle relaxants eg, suxamethonium, lead to excessive neuromuscular blockade; therefore, this combination must be used with caution.
Structurally Related Local Anaesthetics: Lignocaine should be used with caution in patients receiving agents structurally related to local anaesthetics.
Alkaline Solutions: The solubility of lignocaine is limited at pH values >7. This must be taken into consideration if adding an alkaline solution since precipitation might occur at higher pH values.
Laboratory Test Effects: Creatinine: Creatinine measurements in patients with therapeutic plasma levels of lignocaine are about 15-35% higher when measured by an enzymatic method versus the Jaffe method. This appears to be due to assay interference from N-ethylglycine, a metabolite of lignocaine.
Creatine Kinase: The IM injection of lignocaine may result in an increase in creatine kinase levels for up to 48 hrs. This may interfere with the diagnosis of myocardial infarction.