Lidocaine, also known as xylocaine and lignocaine, is a medication used to numb tissue in a specific area.

It is also used to treat ventricular tachycardia and to perform nerve blocks.

When mixed with a small amount of epinephrine is available to allow larger doses for numbing, to decrease bleeding, and to make the numbing effect last longer.

When used as an injectable, it typically begins working within four minutes and lasts for half an hour to three hours.

Lidocaine infusions affects the sodium channel by blocking action potential generation in healthy nerves and reduces neuronal hyperexcitability and spontaneous firing in injured nerves.

Lidocaine infusions may be effective in managing chronic pain and with musculoskeletal problems such as fibromyalgia, ruptured disc or amputated limbs.

Lidocaine mixtures may also be applied directly to the skin or mucous membranes to numb the area.

Pregnancy category B (No risk in non-human studies)

Routes of administration intravenous, subcutaneous, topical, and oral.

OTC for ≤4% for topical application for skin numbing use.

or ≤5% for anorectal hemorroidal pain and to prevent premature ejaculation.

Above 5% or other routes of administration.

Bioavailability 35% by mouth.

3% (topical)

Metabolism is by liver with 90% CYP3A4-mediated.

Onset of action within 1.5 min (IV).

Biological half-life 1.5 h to 2 h.

Duration of action 10 min to 20 min(IV), 0.5 h to 3 h (injection).

Excretion by Kidney

Common side effects with intravenous use: include sleepiness, muscle twitching, confusion, changes in vision, numbness, tingling, and vomiting, hypotension, and an irregular heart rate.

Generally safe for use in pregnancy.

Lower doses may be required in patients with liver disease.

As a local anaesthetic is characterized by a rapid onset of action and intermediate duration of efficacy.

It is suitable for infiltration, block, and surface anaesthesia.

Longer-acting substances such as bupivacaine are sometimes given preference for spinal and epidural anaesthesias

Lidocaine has a rapid onset of action.

Adrenaline vasoconstricts arteries, reducing bleeding and delays the resorption of lidocaine, almost doubling the duration of anaesthesia.

Surface anaesthesia formulations can be used for endoscopies,and before intubations.

Buffering the pH of lidocaine makes local numbing less painful.

Lidocaine drops can be used on the eyes for short ophthalmic procedures.

Some evidence for topical lidocaine for neuropathic pain, and for the treatment of premature ejaculation.

The most important class-1b antiarrhythmic drug.

Can be used intravenously for the treatment of ventricular arrhythmias, acute myocardial infarction, digoxin poisoning, cardioversion, or cardiac catheterization, if amiodarone is not available or contraindicated.

Lidocaine should be given for ventricular arrhythmias after defibrillation, CPR, and vasopressors have been initiated.

Inhaled lidocaine can be used as a cough suppressor acting peripherally, and can be used in intubated patients as it reduces the incidence of coughing and any tracheal damage it might cause when coughing.

May help in treating jellyfish stings, both numbing the affected area and preventing further nematocyst discharge.

For gastritis, drinking viscous lidocaine may help with the pain.

Relative insensitivity to lidocaine is genetic.

Some individuals with Ehlers-Danlos syndrome are insensitive to lidocaine.

Lidocaine, usually in the form of lignocaine hydrochloride, is available in various forms including many topical formulations and solutions for injection or infusion.

Lidocaine hydrochloride 2% epinephrine 1:80,000 solution for injection in a cartridge

Lidocaine hydrochloride 1% solution for injection

Topical lidocaine spray


2% viscous lidocaine

Adverse drug are rare when used as a local anesthetic.

Excessive systemic exposure to mainly result in central nervous system (CNS) and cardiovascular effects.

CNS effects usually occur at lower blood plasma concentrations and additional cardiovascular effects present at higher concentrations.

Cardiovascular toxicity includes hypotension, bradycardia, arrhythmias, flushing, venous insufficiency, increased defibrillator threshold, edema, and/or cardiac arrest – some of which may be due to hypoxemia secondary to respiratory depression.

Respiratory toxicity include bronchospasm, dyspnea, respiratory depression or arrest.

Gastrointestinal side effects would include metallic taste, nausea, vomiting.

Optic side effects include tinnitus

Eye toxicity includes: burning, conjunctival redness, corneal epithelial changes, diplopia, and visual changes

Skin effects :itching, depigmentation, rash, urticaria, edema, angioedema, bruising, inflammation of the vein at the injection site, irritation of the skin when applied topically

Common adverse side effects include: headache, dizziness, drowsiness, confusion, visual disturbances, tinnitus, tremor, and/or paraesthesia.

Infrequent adverse side effects include: hypotension, bradycardia, arrhythmias, cardiac arrest, muscle twitching, seizures, coma, and/or respiratory depression

It is generally safe to use lidocaine with the vasoconstrictor epinephrine including in regions such as the nose, ears, fingers and toes.

Drugs that are also metabolize as CYP3A4 and CYP1A2 can potentially increase serum levels and potential for toxicity or decrease serum levels and the efficacy, depending on whether they induce or inhibit the enzymes, respectively.

Absolute contraindications for use include:

Heart block, second or third degree without pacemaker

Severe sinoatrial block without pacemaker.

Concurrent treatment with quinidine, flecainide, disopyramide, and procainamide

Prior use of amiodarone hydrochloride.

Adams-Stokes syndrome.

Wolff-Parkinson-White syndrome.

Lidocaine viscous is not recommended to treat teething pain in children and infants.

Caution is used in patients with:



Accelerated idioventricular rhythm

Elderly patients

Pseudocholinesterase deficiency.

Intra-articular infusion


Impaired liver function

Adverse reactions include: neurological symptoms.

Overdoses can be a result of excessive administration by topical or parenteral routes, accidental oral ingestion of topical preparations by children who are more susceptible to overdose, accidental intravenous injection, or prolonged use of subcutaneous infiltration anesthesia.

Overdose occurrences have often led to severe toxicity or death in both children and adults.

Lidocaine and its two major metabolites may be quantified in blood, plasma, or serum to confirm the diagnosis of overdose.

It alters signal conduction in neurons by blocking the fast voltage-gated Na+ channels in the neuronal cell membrane responsible for signal propagation.

This fast voltage-gated Na+ channel blockage, prevents the membrane of the postsynaptic neuron from depolarizing and fails to transmit an action potential creating anesthesia.

The anaesthetic effect prevents pain signals from propagating to the brain, and also stops them before they begin.

It blocks sodium channels in the conduction system, as well as the muscle cells of the heart, raises the depolarization threshold, making the heart less likely to initiate or conduct early action potentials that may cause an arrhythmia.

When given IV it typically begins working within four minutes and lasts for half an hour to three hours.

Lidocaine is about 95% metabolized in the liver mainly by CYP3A4 to the pharmacologically active metabolites.

About 60% to 80% circulates bound to the protein alpha1 acid glycoprotein.

The oral bioavailability is 35% and the topical bioavailability is 3%.

Half-life of lidocaine is biphasic and around 90 min to 120 min in most patients, and may be prolonged in patients with hepatic impairment or congestive heart failure.

Is excreted in the urine+90% as metabolites and 10% as unchanged drug.

Xylocaine is a brandname.

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