Lidocaine, also known as lignocaine and sold under the brand name Xylocaine among others, is a local anesthetic of the amino amide type.[
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If injected intravenously, it may cause cerebral effects such as confusion, changes in vision, numbness, tingling, and vomiting.[ It can cause hypotension and an irregular heart rate.][ There are concerns that injecting it into a joint can cause problems with the cartilage.][ It appears to be generally safe for use in pregnancy.][ A lower dose may be required in those with liver problems.][ It is generally safe to use in those allergic to tetracaine or benzocaine.][ Lidocaine is an antiarrhythmic medication of the class Ib type.][ This means it works by blocking sodium channels thus decreasing the rate of contractions of the heart.][ When injected near nerves, the nerves cannot conduct signals to or from the brain.][
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Lidocaine was discovered in 1946 and went on sale in 1948.
Medical uses
Local numbing agent
The efficacy profile of lidocaine as a local anaesthetic is characterized by a rapid onset of action and intermediate duration of efficacy.[ Therefore, lidocaine is suitable for infiltration, block, and surface anaesthesia. Longer-acting substances such as bupivacaine are sometimes given preference for spinal and epidural anaesthesias; lidocaine, though, has the advantage of a rapid onset of action.][
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Lidocaine is one of the most commonly used local anaesthetics in dentistry. It can be administered in multiple ways, most often as a nerve block or infiltration, depending on the type of treatment carried out and the area of the mouth worked on.[
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For surface anaesthesia, several formulations can be used for Endoscopy, before . Lidocaine drops can be used on the eyes for short ophthalmic procedures. There is tentative evidence for topical lidocaine for neuropathic pain and Skin grafting donor site pain.
An adhesive transdermal patch containing a 5% concentration of lidocaine in a hydrogel bandage, is approved by the US FDA for reducing nerve pain caused by shingles.
Heart arrhythmia
Lidocaine is a common 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 have been initiated. A routine preventive dose is no longer recommended after a myocardial infarction as the overall benefit is not convincing.]
Epilepsy
A 2013 review on treatment for recommended intravenous lidocaine as a second-line treatment, if phenobarbital fails to stop seizures.
Other
Intravenous lidocaine infusions are also used to treat chronic pain and Acute pain as an opiate sparing technique. The quality of evidence for this use is poor so it is difficult to compare it to placebo or an epidural.
Inhaled lidocaine can be used as a antitussive acting peripherally to reduce the cough reflex. This application can be implemented as a safety and comfort measure for people needing intubation, as it reduces the incidence of coughing and any tracheal damage it might cause when emerging from anaesthesia.
A 2019 systematic review of the literature found that intraurethral lidocaine reduces pain in men who undergo Cystoscopy procedures.
Lidocaine, along with ethanol, ammonia, and acetic acid, may also help in treating jellyfish stings, both numbing the affected area and preventing further nematocyst discharge.
For gastritis, drinking a viscous lidocaine formulation may help with the pain.
A 2021 study found that lidocaine 5% spray on glans penis 10-20 minutes prior to sexual intercourse significantly improves premature ejaculation.
Adverse effects
Adverse drug reactions (ADRs) are rare when lidocaine is used as a local anesthetic and is administered correctly. Most ADRs associated with lidocaine for anesthesia relate to administration technique (resulting in systemic exposure) or pharmacological effects of anesthesia, and allergy reactions only rarely occur.
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CNS excitation: nervousness, agitation, anxiety, apprehension, tingling around the mouth (circumoral paraesthesia), headache, hyperesthesia, tremor, dizziness, pupillary changes, psychosis, euphoria, hallucinations, and seizures
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CNS depression with heavier exposure: drowsiness, lethargy, slurred speech, hypoesthesia, confusion, disorientation, loss of consciousness, respiratory depression, and apnoea.
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Cardiovascular: hypotension, bradycardia, Heart arrhythmia, flushing, venous insufficiency, increased defibrillator threshold, edema, and/or cardiac arrest – some of which may be due to hypoxemia secondary to respiratory depression.
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Respiratory: bronchospasm, dyspnea, respiratory depression or arrest
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Gastrointestinal: metallic taste, nausea, vomiting, agita, and diarrhea
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Ears: tinnitus
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Eyes: local burning, conjunctival hyperemia, corneal epithelial changes/ulceration, diplopia, visual changes (opacification)
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Skin: itching, depigmentation, rash, urticaria, edema, angioedema, bruising, thrombophlebitis at the injection site, irritation of the skin when applied topically
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Blood: methemoglobinemia
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Allergy
ADRs associated with the use of intravenous lidocaine are similar to the toxic effects of systemic exposure above. These are dose-related and more frequent at high infusion rates (≥3 mg/min). Common ADRs include headache, dizziness, drowsiness, confusion, visual disturbances, tinnitus, tremor, and/or paraesthesia. Infrequent ADRs associated with the use of lidocaine include: hypotension, bradycardia, Heart arrhythmia, cardiac arrest, muscle twitching, , coma, and/or respiratory depression.[
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It is generally safe to use lidocaine with vasoconstrictors such as adrenaline, including in regions such as the nose, ears, , and toes.[
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The use of lidocaine for spinal anesthesia may lead to an increased risk of transient neurological symptoms, a painful condition that is sometimes experienced immediately after surgery.
Interactions
Any drugs that are also of 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. Drugs that may increase the chance of methemoglobinemia should also be considered carefully. Dronedarone and liposomal morphine are both absolutely a contraindication, as they may increase the serum levels, but hundreds of other drugs require monitoring for interaction.
Contraindications
Absolute contraindications for the use of lidocaine include:
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Heart block, second or third degree (without pacemaker)
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Severe sinoatrial block (without pacemaker)
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Serious adverse drug reaction to lidocaine or amide local anesthetics
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Hypersensitivity to corn and corn-related products (corn-derived dextrose is used in the mixed injections)
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Concurrent treatment with quinidine, flecainide, disopyramide, procainamide (class I antiarrhythmic agents)
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Prior use of amiodarone hydrochloride
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Adams–Stokes syndrome
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Wolff–Parkinson–White syndrome
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Lidocaine viscous is not recommended by the FDA to treat teething pain in children and infants.
Exercise caution in people with any of these:
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Hypotension not due to Heart arrhythmia
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Bradycardia
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Accelerated idioventricular rhythm
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Elderly
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Ehlers–Danlos syndromes; efficiency of local anesthetics can be reduced
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Pseudocholinesterase deficiency
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Intra-articular infusion (this is not an approved indication and can cause chondrolysis)
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Porphyria, especially acute intermittent porphyria; lidocaine has been classified as porphyrogenic because of the hepatic enzymes it induces,
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Impaired liver function – people with lowered hepatic function may have an adverse reaction with repeated administration of lidocaine because the drug is metabolized by the liver. Adverse reactions may include neurological symptoms (e.g. dizziness, nausea, muscle twitches, vomiting, or seizures).
Overdosage
Overdoses of lidocaine may result from excessive administration by topical or parenteral routes, accidental oral ingestion of topical preparations by children (who are more susceptible to overdose), accidental intravenous (rather than subcutaneous, intrathecal, or paracervical) injection, or from prolonged use of subcutaneous infiltration anesthesia during cosmetic surgery. The maximum safe dose is 3 mg per kg.[
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Such overdoses have often led to severe toxicity or death in both children and adults (local anesthetic systemic toxicity).
Lidocaine is often given intravenously as an antiarrhythmic agent in critical cardiac-care situations.
Lidocaine has been used by veterinarians for euthanasia of horses, livestock, and more recently of dogs and
/ref> Due to its side effects, intravenous lidocaine can be given only to anesthetized patients, making it less attractive perhaps than pentobarbital, that can be given intravenously to awake patients. In 2025 Russian Army nurses have reported the use of 1-2 % intravenous lidocaine in 60 mL dosage for
/ref>
Postarthroscopic glenohumeral chondrolysis
Lidocaine in large amounts may be toxic to cartilage and intra-articular infusions can lead to postarthroscopic glenohumeral chondrolysis.
Pharmacology
Mechanism of action
Lidocaine alters signal conduction in by prolonging the inactivation of the fast sodium channel in the neuronal cell membrane responsible for action potential propagation.
The same principle applies to this drug's actions in the heart. Blocking 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.
Pharmacokinetics
When used as an injectable it typically begins working within four minutes and lasts for half an hour to three hours.[ Lidocaine is about 95% metabolized (dealkylated) in the liver mainly by CYP3A4 to the pharmacologically active metabolites monoethylglycinexylidide (MEGX) and then subsequently to the inactive glycine xylidide. MEGX has a longer half-life than lidocaine, but also is a less potent sodium channel blocker.][
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The elimination half-life of lidocaine is biphasic and around 90 min to 120 min in most people. This may be prolonged in people with liver failure (average 343 min) or heart failure (average 136 min).
Chemistry
Molecular structure and conformational flexibility
Lidocaine's 1,5-dimethylbenzene group gives it hydrophobic properties. In addition to this aromatic unit, lidocaine has an aliphatic section comprising amide, carbonyl, and enyl groups.
Lidocaine exhibits a remarkable degree of conformational flexibility, resulting in more than 60 probable conformers.
Influence of temperature and pressure on conformational preference
The dynamic transformation of lidocaine conformers in supercritical carbon dioxide (scCO2) highly depends on external factors such as pressure
Veterinary use
Lidocaine is commonly used in veterinary medicine in both companion and production animals around the world and is listed as an essential veterinary medicine by the World Veterinary Association and also the World Small Animal Veterinary Association.[1]
In veterinary medicine, it is commonly used as a local anaesthetic both as an injectable or topical product. It provides excellent local anaesthesia when given by local infiltration into a tissue or via specific nerve blocks. These are commonly applied to nerves of the head, limbs, thorax, and spine. It can also be used to treat ventricular arrhythmias when given intravenously. In most veterinary species, when given via injection, it has a rapid onset of action (2-10 minutes) with a duration of action of 30-60 minutes.
In veterinary species, its metabolism is much the same as humans with rapid metabolism in the liver to the major metabolites MEGX (monoethylglycine xylidide) and GX (glycine xylidide) that retain partial activity against sodium channels. These compounds are further metabolized to monoethylglycine and xylidide, respectively.
Toxicity in animals is similar to that seen in humans with both toxicity to the central nervous system (CNS) and cardiovascular system observed. General the CNS signs are seen first with agitation and muscle twitching seen before the cardiovascular signs of hypotension, myocardial depression, and arrhythmias. Further CNS depression will result from higher doses with seizures and convulsions and eventually apnea and death.
It is a component of the veterinary drug Tributame along with embutramide and chloroquine used to carry out euthanasia on horses and dogs.
History
Lidocaine, the first amino amide–type local anesthetic (previous were amino esters), was first synthesized under the name 'xylocaine' by Swedish chemist Nils Löfgren in 1943.
Society and culture
Dosage forms
Lidocaine, usually in the form of its Hydrochloride, is available in various forms including many topical formulations and solutions for injection or infusion.
File:Lidocaine HCl local anesthetic cartridge.JPG|Lidocaine hydrochloride 2% epinephrine 1:80,000 solution for injection in a cartridge
File:Lidocaine hci.jpg|Lidocaine hydrochloride 1% solution for injection
File:Xylocaina spray.jpg|Topical lidocaine spray
File:Vicouslodi.jpeg|2% viscous lidocaine
Names
Lidocaine is the International Nonproprietary Name (INN), British Approved Name (BAN), and Australian Approved Name (AAN),
Xylocaine is a brand name, referring to the major synthetic building block 2,6-xylidine. The "ligno" prefix is chosen because "xylo" means wood in Greek while "ligno" means the same in Latin. The "lido" prefix instead refers to the fact that the drug is chemically related to acetanilide.[
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Recreational use
lidocaine is not listed by the World Anti-Doping Agency as a substance whose use is banned in sport.
Adulterant in cocaine
Lidocaine is often added to cocaine as a diluent.
Compendial status
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Japanese Pharmacopoeia 15
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United States Pharmacopeia 31
External links
