Lidocaine

Lidocaine,xylocaine, or lignocaine is a common local anesthetic and class-1b antiarrhythmic drug. Lidocaine is used topically to relieve itching, burning, and pain from skin inflammations, injected as a dental anesthetic, or used as a local anesthetic for minor surgery.

The efficacy profile of lidocaine as a local anesthetic is characterized by a rapid onset of action and intermediate duration of efficacy. Therefore, lidocaine is suitable for infiltration, block, and surface anesthesia. Longer-acting substances such as bupivacaine are sometimes given preference for subdural and epidural anesthesias; lidocaine, though, has the advantage of a rapid onset of action. Epinephrine (adrenaline) vasoconstricts arteries, reducing bleeding and also delays the resorption of lidocaine, almost doubling the duration of anaesthesia. For surface anesthesia, several available formulations can be used for endoscopies, before intubations, etc. Buffering the pH of lidocaine makes local freezing less painful.Lidocaine drops can be used on the eyes for short ophthalmic procedures.

There is tentative evidence for topical lidocaine for neuropathic pain.Intravenous lidocaine also has uses as a temporary fix for tinnitus. Although not completely curing the disorder, it has been shown to reduce the effects by around two-thirds.

Lidocaine is also the most important class-1b antiarrhythmic drug; it is used intravenously for the treatment of ventricular arrhythmias (for acute myocardial infarction, digoxin poisoning, cardioversion, or cardiac catheterization) if amiodarone is not available or contraindicated. Lidocaine should be given for this indication after defibrillation, CPR, and vasopressors have been initiated. A routine prophylactic administration is no longer recommended for acute cardiac infarction; the overall benefit of this measure is not convincing.

Inhaled lidocaine can be used as an antitussive (cough suppressor) acting peripherally to reduce the cough reflex. This application can be implemented as a safety and comfort measure for patients who have to be intubated, as it reduces the incidence of coughing and any tracheal damage it might cause when emerging from anesthesia.

Lidocaine, along with ethanol, ammonia, and acetic acid, has also been proven to be effective in treating jellyfish stings, both numbing the affected area and preventing further nematocyst discharge.