Lidocaine

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.

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.

For surface anaesthesia, several formulations can be used for endoscopies, before intubations. Lidocaine drops can be used on the eyes for short ophthalmic procedures. There is tentative evidence for topical lidocaine for neuropathic pain and skin graft donor site pain.{{cite journal | vauthors = Derry S, Wiffen PJ, Moore RA, Quinlan J | veditors = Derry S | title = Topical lidocaine for neuropathic pain in adults | journal = The Cochrane Database of Systematic Reviews | volume = 7 | issue = 7 | pages = CD010958 | date = July 2014 | pmid = 25058164 | doi = 10.1002/14651858.CD010958.pub2 | pmc = 6540846 }}{{cite journal | vauthors = Sinha S, Schreiner AJ, Biernaskie J, Nickerson D, Gabriel VA | title = Treating pain on skin graft donor sites: Review and clinical recommendations | journal = The Journal of Trauma and Acute Care Surgery | volume = 83 | issue = 5 | pages = 954–964 | date = November 2017 | pmid = 28598907 | doi = 10.1097/TA.0000000000001615 | s2cid = 44520644 }} As a local numbing agent, it is used for the treatment of premature ejaculation.{{cite journal | title = Lidocaine/prilocaine spray for premature ejaculation | journal = Drug and Therapeutics Bulletin | volume = 55 | issue = 4 | pages = 45–48 | date = April 2017 | pmid = 28408390 | doi = 10.1136/dtb.2017.4.0469 | s2cid = 19110955 }}

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.{{cite journal | vauthors = Kumar M, Chawla R, Goyal M | title = Topical anesthesia | journal = Journal of Anaesthesiology Clinical Pharmacology | volume = 31 | issue = 4 | pages = 450–6 | date = 2015 | pmid = 26702198 | pmc = 4676230 | doi = 10.4103/0970-9185.169049 | doi-access = free }} The transdermal patch is also used for pain from other causes, such as compressed nerves and persistent nerve pain after some surgeries.

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 vasopressors have been initiated. A routine preventive dose is no longer recommended after a myocardial infarction as the overall benefit is not convincing.{{cite journal | vauthors = Martí-Carvajal AJ, Simancas-Racines D, Anand V, Bangdiwala S | title = Prophylactic lidocaine for myocardial infarction | journal = The Cochrane Database of Systematic Reviews | volume = 8 | issue = 8 | pages = CD008553 | date = August 2015 | pmid = 26295202 | doi = 10.1002/14651858.CD008553.pub2 | pmc = 8454263 }}

A 2013 review on treatment for neonatal seizures recommended intravenous lidocaine as a second-line treatment, if phenobarbital fails to stop seizures.{{cite journal | vauthors = Slaughter LA, Patel AD, Slaughter JL | title = Pharmacological treatment of neonatal seizures: a systematic review | journal = Journal of Child Neurology | volume = 28 | issue = 3 | pages = 351–64 | date = March 2013 | pmid = 23318696 | pmc = 3805825 | doi = 10.1177/0883073812470734 }}

Intravenous lidocaine infusions are also used to treat chronic pain and acute surgical 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.{{cite journal | vauthors = Weibel S, Jelting Y, Pace NL, Helf A, Eberhart LH, Hahnenkamp K, Hollmann MW, Poepping DM, Schnabel A, Kranke P | title = Continuous intravenous perioperative lidocaine infusion for postoperative pain and recovery in adults | journal = The Cochrane Database of Systematic Reviews | volume = 2018 | pages = CD009642 | date = June 2018 | issue = 6 | pmid = 29864216 | pmc = 6513586 | doi = 10.1002/14651858.cd009642.pub3 }}

Inhaled lidocaine can be used as a cough suppressor 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.{{cite book |veditors=Berger AM, Shuster JL, Von Roenn JH | title = Principles and practice of palliative care and supportive oncology | publisher = Lippincott Williams & Wilkins | location = Hagerstwon, MD |year=2007 | isbn = 978-0-7817-9595-1 | vauthors = Biller JA | chapter = Airway obstruction, bronchospasm, and cough | chapter-url = https://books.google.com/books?id=LngD6RFXY_AC&pg=PA297 | pages = 297–307 | quote = Inhaled lidocaine is used to suppress cough during bronchoscopy. Animal studies and a few human studies suggest that lidocaine has an antitussive effect…}}

A 2019 systematic review of the literature found that intraurethral lidocaine reduces pain in men who undergo cystoscopic procedures.{{cite journal | vauthors = Raskolnikov D, Brown B, Holt SK, Ball AL, Lotan Y, Strope S, Schroeck F, Ullman R, Lipman R, Smith AB, Gore JL | title = Reduction of Pain during Flexible Cystoscopy: A Systematic Review and Meta-Analysis | journal = The Journal of Urology | volume = 202 | issue = 6 | pages = 1136–1142 | date = December 2019 | pmid = 31219763 | doi = 10.1097/JU.0000000000000399 | s2cid = 195192577 }}

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.{{cite journal |vauthors=Birsa LM, Verity PG, Lee RF | title = Evaluation of the effects of various chemicals on discharge of and pain caused by jellyfish nematocysts | journal = Comp. Biochem. Physiol. C | volume = 151 | issue = 4 | pages = 426–30 | date = May 2010 | pmid = 20116454 | doi = 10.1016/j.cbpc.2010.01.007 }}{{cite journal |vauthors=Morabito R, Marino A, Dossena S, La Spada G | title = Nematocyst discharge in Pelagia noctiluca (Cnidaria, Scyphozoa) oral arms can be affected by lidocaine, ethanol, ammonia and acetic acid | journal = Toxicon | volume = 83 | pages = 52–8 | date = Jun 2014 | pmid = 24637105 | doi=10.1016/j.toxicon.2014.03.002| bibcode = 2014Txcn...83...52M }}

For gastritis, drinking a viscous lidocaine formulation may help with the pain.{{cite book| vauthors = Adams JG |title=Emergency Medicine: Clinical Essentials|date=2012|publisher=Elsevier Health Sciences|isbn=9781455733941|chapter-url=https://books.google.com/books?id=rpoH-KYE93IC&pg=PP1314|chapter=32|url-status=live|archive-url= https://web.archive.org/web/20170908150741/https://books.google.com/books?id=rpoH-KYE93IC&pg=PP1314 |archive-date=8 September 2017}}

A 2021 study found that lidocaine 5% spray on glans penis 10-20 minutes prior to sexual intercourse significantly improves premature ejaculation.{{cite journal | vauthors = Abu El-Hamd M | title = Effectiveness and tolerability of lidocaine 5% spray in the treatment of lifelong premature ejaculation patients: a randomized single-blind placebo-controlled clinical trial | journal = International Journal of Impotence Research | volume = 33 | issue = 1 | pages = 96–101 | date = January 2021 | pmid = 31896832 | doi = 10.1038/s41443-019-0225-9 }} Another study found that lidocaine-prilocaine cream 5% is effective in premature ejaculation and 20 minutes of application time before sexual intercourse.{{cite journal | vauthors = Atikeler MK, Gecit I, Senol FA | title = Optimum usage of prilocaine-lidocaine cream in premature ejaculation | journal = Andrologia | volume = 34 | issue = 6 | pages = 356–359 | date = December 2002 | pmid = 12472618 | doi = 10.1046/j.1439-0272.2002.00511.x | doi-access = free }}

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 allergic reactions only rarely occur.{{cite journal |vauthors=Jackson D, Chen AH, Bennett CR |title = Identifying true lidocaine allergy |journal = J Am Dent Assoc |volume = 125 |issue = 10 |pages = 1362–6 |date = October 1994 |pmid = 7844301 |doi = 10.14219/jada.archive.1994.0180}} Systemic exposure to excessive quantities of lidocaine mainly results 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, though cardiovascular collapse may also occur with low concentrations. ADRs by individual organ systems are:

• CNS excitation: nervousness, agitation, anxiety, apprehension, tingling around the mouth (circumoral paraesthesia), headache, hyperesthesia, tremor, dizziness, pupillary changes, psychosis, euphoria, hallucinations, and seizures
• CNS depression with increasingly heavier exposure: drowsiness, lethargy, slurred speech, hypoesthesia, confusion, disorientation, loss of consciousness, respiratory depression and apnoea.
• Cardiovascular: 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.{{cite book |title = Australian Medicines Handbook |publisher = Australian Medicines Handbook Pty Ltd |location = Adelaide, S. Aust |year = 2006 | isbn = 978-0-9757919-2-9 | title-link = Australian Medicines Handbook }}{{page needed|date=May 2013}}
• Respiratory: bronchospasm, dyspnea, respiratory depression or arrest
• Gastrointestinal: metallic taste, nausea, vomiting, agita, and diarrhea
• Ears: tinnitus
• Eyes: local burning, conjunctival hyperemia, corneal epithelial changes/ulceration, diplopia, visual changes (opacification)
• Skin: itching, depigmentation, rash, urticaria, edema, angioedema, bruising, inflammation of the vein at the injection site, irritation of the skin when applied topically
• Blood: methemoglobinemia
• 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, arrhythmias, cardiac arrest, muscle twitching, seizures, coma, and/or respiratory depression.

It is generally safe to use lidocaine with vasoconstrictors such as adrenaline, including in regions such as the nose, ears, fingers, and toes.{{cite journal |vauthors = Nielsen LJ, Lumholt P, Hölmich LR |title = [Local anaesthesia with vasoconstrictor is safe to use in areas with end-arteries in fingers, toes, noses, and ears] |journal = Ugeskrift for Laeger |volume = 176 |issue = 44 |date = October 2014 |pmid = 25354008 }} While concerns of tissue death, if used in these areas, have been raised, the evidence does not support these concerns.

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.{{cite journal | vauthors = Forget P, Borovac JA, Thackeray EM, Pace NL | title = Transient neurological symptoms (TNS) following spinal anaesthesia with lidocaine versus other local anaesthetics in adult surgical patients: a network meta-analysis | journal = The Cochrane Database of Systematic Reviews | volume = 2019 | pages = CD003006 | date = December 2019 | issue = 12 | pmid = 31786810 | pmc = 6885375 | doi = 10.1002/14651858.CD003006.pub4 }} There is some weak evidence to suggest that the use of alternative anesthetic medications such as prilocaine, procaine, bupivacaine, ropivacaine, or levobupivacaine may decrease the risk of a person developing transient neurological symptoms. Low-quality evidence suggests that 2‐chloroprocaine and mepivacaine when used for spinal anesthetic have a similar risk of the person developing transient neurological symptoms as lidocaine.

Any drugs that are also ligands 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.{{cite web |url=https://online.epocrates.com/u/104316/lidocaine/Drug+Interactions |title=Lidocaine|publisher=Epocrates |url-status=live |archive-url=https://web.archive.org/web/20140422232823/https://online.epocrates.com/u/104316/lidocaine/Drug+Interactions |archive-date=22 April 2014}}

Absolute contraindications for the use of lidocaine include:

• Heart block, second or third degree (without pacemaker)
• Severe sinoatrial block (without pacemaker)
• Serious adverse drug reaction to lidocaine or amide local anesthetics
• Hypersensitivity to corn and corn-related products (corn-derived dextrose is used in the mixed injections)
• Concurrent treatment with quinidine, flecainide, disopyramide, procainamide (class I antiarrhythmic agents)
• Prior use of amiodarone hydrochloride
• Adams–Stokes syndrome{{cite web |url = https://www.fda.gov/Safety/MedWatch/SafetyInformation/ucm342035.htm |title = Lidocaine Hydrochloride and 5% Dextrose Injection |work = Safety Labeling Changes |publisher = FDA Center for Drug Evaluation and Research (CDER) |date = January 2014 |url-status = dead |archive-url = https://web.archive.org/web/20130403105258/https://www.fda.gov/Safety/MedWatch/SafetyInformation/ucm342035.htm |archive-date = 3 April 2013 }}
• Wolff–Parkinson–White syndrome
• Lidocaine viscous is not recommended by the FDA to treat teething pain in children and infants.{{cite web |url = https://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-fda-recommends-not-using-lidocaine-treat-teething-pain-and-requires |title = FDA Drug Safety Communication: FDA recommends not using lidocaine to treat teething pain and requires new Boxed Warning |publisher = FDA Center for Drug Evaluation and Research (CDER) |date = June 2014 | url-status = dead |archive-url = https://web.archive.org/web/20140714220256/https://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm402790.htm |archive-date = 14 July 2014 }}

Exercise caution in people with any of these:

• Hypotension not due to arrhythmia
• Bradycardia
• Accelerated idioventricular rhythm
• Elderly
• Ehlers–Danlos syndromes; efficiency of local anesthetics can be reduced{{cite journal | vauthors = Schubart JR, Schaefer E, Janicki P, Adhikary SD, Schilling A, Hakim AJ, Bascom R, Francomano CA, Raj SR | title = Resistance to local anesthesia in people with the Ehlers-Danlos Syndromes presenting for dental surgery | journal = Journal of Dental Anesthesia and Pain Medicine | volume = 19 | issue = 5 | pages = 261–270 | date = October 2019 | pmid = 31723666 | pmc = 6834718 | doi = 10.17245/jdapm.2019.19.5.261 | doi-access = free }}
• Pseudocholinesterase deficiency
• Intra-articular infusion (this is not an approved indication and can cause chondrolysis)
• Porphyria, especially acute intermittent porphyria; lidocaine has been classified as porphyrogenic because of the hepatic enzymes it induces,{{cite web |url = http://www.merckmanuals.com/media/professional/pdf/Drugs_porphyria.pdf |title = Table 96–4. Drugs and Porphyria |year = 2011 |work = Merck Manual |publisher = Merck & Company, Inc. |url-status = live |archive-url = https://web.archive.org/web/20140420104822/http://www.merckmanuals.com/media/professional/pdf/Drugs_porphyria.pdf/ |archive-date = 20 April 2014 }} although clinical evidence suggests it is not.{{cite web |url = http://www.drugs-porphyria.org/monograph.php?id=3448 |title = Lidocaine - N01BB02 |work = Drug porphyrinogenicity monograph |publisher = The Norwegian Porphyria Centre and the Swedish Porphyria Centre |quote = strong clinical evidence points to lidocaine as probably not porphyrinogenic |url-status = live |archive-url = https://web.archive.org/web/20140420040511/http://www.drugs-porphyria.org/monograph.php?id=3448 |archive-date = 20 April 2014 }} Bupivacaine is a safe alternative in this case.
• 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).{{cite book | vauthors = Khan MG |title=Cardiac Drug Therapy |date=2007 |publisher=Humana Press |location=Totowa, NJ |isbn=9781597452380 |edition=7th}}

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.{{cn|date=March 2023}} The maximum safe dose is 3 mg per kg.

Such overdoses have often led to severe toxicity or death in both children and adults (local anesthetic systemic toxicity).{{cite journal | vauthors = El-Boghdadly K, Pawa A, Chin KJ | title = Local anesthetic systemic toxicity: current perspectives | journal = Local and Regional Anesthesia | volume = 11 | pages = 35–44 | date = 8 August 2018 | pmid = 30122981 | pmc = 6087022 | doi = 10.2147/LRA.S154512 | doi-access = free }} Symptoms include central nervous system manifestations such as numbness of the tongue, dizziness, tinnitus, visual disturbances, convulsions, reduced consciousness progressing to coma, as well as respiratory arrest and cardiovascular disturbances.{{cite journal | vauthors = van Donselaar-van der Pant KA, Buwalda M, van Leeuwen HJ | title = [Lidocaine: local anaesthetic with systemic toxicity] | language = nl | journal = Nederlands Tijdschrift voor Geneeskunde | volume = 152 | issue = 2 | pages = 61–65 | date = January 2008 | pmid = 18265791 | url = https://www.ntvg.nl/artikelen/lidocaine-een-lokaal-anestheticum-met-systemische-toxiciteit | trans-title = Lidocaine: local anaesthetic with systemic toxicity }} Lidocaine and its two major metabolites may be quantified in blood, plasma, or serum to confirm the diagnosis in potential poisoning victims or to assist forensic investigation in a case of fatal overdose. {{cn|date=December 2022}}

Lidocaine is often given intravenously as an antiarrhythmic agent in critical cardiac-care situations.{{cite book | vauthors = Baselt R |title = Disposition of Toxic Drugs and Chemicals in Man |edition = 8th |publisher = Biomedical Publications | location = Foster City, CA | year = 2008 |pages = 840–4 |isbn = 978-0-9626523-7-0 }} Treatment with intravenous lipid emulsions (used for parenteral feeding) to reverse the effects of local anaesthetic toxicity is becoming more common.{{cite journal | vauthors = Picard J, Ward SC, Zumpe R, Meek T, Barlow J, Harrop-Griffiths W | title = Guidelines and the adoption of 'lipid rescue' therapy for local anaesthetic toxicity | journal = Anaesthesia | volume = 64 | issue = 2 | pages = 122–125 | date = February 2009 | pmid = 19143686 | doi = 10.1111/j.1365-2044.2008.05816.x | s2cid = 25581037 | doi-access = free }}{{cite journal | vauthors = El-Boghdadly K, Pawa A, Chin KJ | title = Local anesthetic systemic toxicity: current perspectives | journal = Local and Regional Anesthesia | volume = 11 | pages = 35–44 | year = 2018 | pmid = 30122981 | pmc = 6087022 | doi = 10.2147/LRA.S154512 | doi-access = free }}

Lidocaine in large amounts may be toxic to cartilage and intra-articular infusions can lead to postarthroscopic glenohumeral chondrolysis.{{cite journal |vauthors = Gulihar A, Robati S, Twaij H, Salih A, Taylor GJ |title = Articular cartilage and local anaesthetic: A systematic review of the current literature |journal = Journal of Orthopaedics |volume = 12 |issue = Suppl 2 |pages = S200-10 |date = December 2015 |pmid = 27047224 |pmc = 4796530 |doi = 10.1016/j.jor.2015.10.005 }}

Lidocaine alters signal conduction in neurons by prolonging the inactivation of the fast voltage-gated Na⁺ channels in the neuronal cell membrane responsible for action potential propagation.{{cite book |doi=10.1002/0470846682.ch14 |chapter=Molecular mechanisms of gating and drug block of sodium channels |title=Sodium Channels and Neuronal Hyperexcitability |series=Novartis Foundation Symposia |year=2001 | vauthors = Carterall WA |isbn=9780470846681 |volume=241 |pages=206–225}} With sufficient blockage, the voltage-gated sodium channels will not open and an action potential will not be generated. Careful titration allows for a high degree of selectivity in the blockage of sensory neurons, whereas higher concentrations also affect other types of neurons.{{cn|date=March 2023}}

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.{{cite journal |vauthors=Sheu SS, Lederer WJ | title = Lidocaine's negative inotropic and antiarrhythmic actions. Dependence on shortening of action potential duration and reduction of intracellular sodium activity | journal = Circulation Research | volume = 57 | issue = 4 | pages = 578–90 | date = Oct 1985 | pmid = 2412723 | doi=10.1161/01.res.57.4.578| doi-access = free }}

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.{{cite book |veditors=Flomenbaum N, Goldfrank LR, Hoffman RL, Howland MD, Lewin NA, Nelson LH | title = Goldfrank's Toxicologic Emergencies | edition = 8th | publisher = McGraw-Hill | location = New York | year = 2006 | pages = 963–4 |vauthors=Lewin NA, Nelson LH | chapter = Chapter 61: Antidysrhythmics | isbn = 978-0-07-143763-9 }} The volume of distribution is 1.1 L/kg to 2.1 L/kg, but congestive heart failure can decrease it. About 60% to 80% circulates bound to the protein alpha₁ acid glycoprotein. The oral bioavailability is 35% and the topical bioavailability is 3%. Lidocaine efficacy may be reduced in tissues that are inflamed, due to competing inflammatory mediators.

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 hepatic impairment (average 343 min) or congestive heart failure (average 136 min).{{cite journal |vauthors=Thomson PD, Melmon KL, Richardson JA, Cohn K, Steinbrunn W, Cudihee R, Rowland M | title = Lidocaine pharmacokinetics in advanced heart failure, liver disease, and renal failure in humans | journal = Ann. Intern. Med. | volume = 78 | issue = 4 | pages = 499–508 | date = April 1973 | pmid = 4694036 | doi = 10.7326/0003-4819-78-4-499 }} Lidocaine is excreted in the urine (90% as metabolites and 10% as unchanged drug).{{cite journal |vauthors=Collinsworth KA, Kalman SM, Harrison DC | title = The clinical pharmacology of lidocaine as an antiarrhythymic drug | journal = Circulation | volume = 50 | issue = 6 | pages = 1217–30 | year = 1974 | pmid = 4609637 | doi = 10.1161/01.CIR.50.6.1217 | doi-access = free }}

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.{{cite journal | vauthors = Khodov IA, Belov KV, Dyshin AA, Krestyaninov MA, Kiselev MG |date= December 2022 |title=Pressure effect on lidocaine conformational equilibria in scCO2: A study by 2D NOESY |journal=Journal of Molecular Liquids |language=en |volume=367 |pages=120525 |doi=10.1016/j.molliq.2022.120525|s2cid= 252799787 }} This adaptability arises from the high lability of the amide and ethyl groups within the molecule. These groups can undergo shifts in their positions, leading to significant variations in the overall molecular configuration.

The dynamic transformation of lidocaine conformers in supercritical carbon dioxide (scCO₂) highly depends on external factors such as pressure and temperature.{{cite journal | vauthors = Khodov IA, Belov KV, Sobornova VV, Dyshin AA, Kiselev MG |date= October 2023 |title=Exploring the temperature-dependent proportions of lidocaine conformers equilibria in supercritical carbon dioxide via NOESY |journal=Journal of Molecular Liquids |language=en |volume=387 |pages=122620 |doi=10.1016/j.molliq.2023.122620|s2cid= 260069284 }} Alterations in these conditions can lead to distinct conformations, impacting the molecule's physicochemical properties. One notable consequence of these variations is the particle size of lidocaine when produced through micronization using scCO₂. Changes in the position of the amide group within the molecule can trigger a redistribution of intra- and intermolecular hydrogen bonds, affecting the outcome of the micronization process and the resultant particle size.{{cite journal | vauthors = Kuznetsova IV, Gilmutdinov II, Gilmutdinov IM, Sabirzyanov AN |date= September 2019 |title=Production of Lidocaine Nanoforms via the Rapid Extension of a Supercritical Solution into Water Medium |journal=High Temperature |language=en |volume=57 |issue=5 |pages=726–730 |doi=10.1134/S0018151X19040138 |bibcode= 2019HTemp..57..726K |s2cid= 213017906 |issn=0018-151X}}

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.[https://worldvet.org/evml/]{{Cite journal |title=The 2023 World Small Animal Veterinary Association (WSAVA) list of essential medicines for cats and dogs |url=https://wsava.org/wp-content/uploads/2023/11/2023-essential-medicines-for-cats-and-dogs.pdf |journal=Journal of Small Animal Practice}}

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.{{Cite book |title=Veterinary Pharmacology and Therapeutics |year=2018 |edition=10th}}

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.{{cite book |url=https://books.google.com/books?id=BLkPFlB15v0C |title=Small Animal Toxicology |vauthors=Peterson ME, Talcott PA |date=7 August 2013 |publisher=Elsevier Health Sciences |isbn=978-0323241984 |language=en |archive-url=https://web.archive.org/web/20170908150741/https://books.google.com/books?id=BLkPFlB15v0C |archive-date=8 September 2017 |url-status=live}}{{cite web |title=FDA Freedom of Information Summary - Tributame |url=https://www.fda.gov/downloads/AnimalVeterinary/Products/ApprovedAnimalDrugProducts/FOIADrugSummaries/ucm051493.pdf |url-status=dead |archive-url=https://web.archive.org/web/20150518090208/https://www.fda.gov/downloads/animalveterinary/products/approvedanimaldrugproducts/foiadrugsummaries/ucm051493.pdf |archive-date=18 May 2015 |website=Food and Drug Administration}}

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.{{cite book | vauthors = Löfgren N |title=Studies on local anesthetics: Xylocaine: a new synthetic drug |type=Inaugural dissertation |publisher=Ivar Heggstroms |location=Stockholm, Sweden |year=1948 |oclc=646046738}}{{page needed|date=May 2013}}{{cite journal |vauthors=Löfgren N, Lundqvist B | year = 1946 | title = Studies on local anaesthetics II | journal = Svensk Kemisk Tidskrift | volume = 58 | pages = 206–17}}{{cite journal | vauthors = Wildsmith JA | year = 2011 | title = Lidocaine: A more complex story than 'simple' chemistry suggests | journal = The Proceedings of the History of Anaesthesia Society | url = http://www.histansoc.org.uk/uploads/9/5/5/2/9552670/vol_43.pdf | volume = 43 | pages = 9–16 | url-status = live | archive-url = https://web.archive.org/web/20140422232909/http://www.histansoc.org.uk/uploads/9/5/5/2/9552670/vol_43.pdf | archive-date = 22 April 2014 }} His colleague Bengt Lundqvist performed the first injection anesthesia experiments on himself. It was first marketed in 1949.

Lidocaine, usually in the form of its hydrochloride salt, is available in various forms including many topical formulations and solutions for injection or infusion.{{cite web|title=Lidocaine international forms and names|url=https://www.drugs.com/international/lidocaine.html|publisher=Drugs.com|access-date=29 October 2017}} It is also available as a transdermal patch, which is applied directly to the skin.{{cn|date=March 2023}}

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

Lidocaine is the International Nonproprietary Name (INN), British Approved Name (BAN), and Australian Approved Name (AAN),{{cite web |title=Lidocaine Ingredient Summary|url=https://www.ebs.tga.gov.au/ebs/PublicHTML/pdfstore.nsf/TemplateEngineIngredientPDF?OpenAgent&ingredientid=100665&docid=BB294B9EA22D3A2ACA2577DD0000F98B |website=Therapeutic Goods Administration |access-date=20 September 2018 }} while lignocaine is the former BAN{{citation needed|date=February 2020}} and AAN. Both the old and new names will be displayed on the product label in Australia until at least 2023.{{cite web |title=Updating medicine ingredient names - list of affected ingredients |url=https://www.tga.gov.au/node/711438 |website=Therapeutic Goods Administration |date=24 June 2019 |access-date=16 February 2020 |archive-date=28 August 2021 |archive-url=https://web.archive.org/web/20210828143930/https://www.tga.gov.au/updating-medicine-ingredient-names-list-affected-ingredients |url-status=dead }}

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.

{{As of|2021||post=,}} lidocaine is not listed by the World Anti-Doping Agency as a substance whose use is banned in sport.{{cite web|date=1 January 2021|title=The 2021 Prohibited List International Standard|url=https://www.wada-ama.org/sites/default/files/resources/files/2021_wada_code.pdf|archive-url=https://web.archive.org/web/20210513023441/https://www.wada-ama.org/sites/default/files/resources/files/2021_wada_code.pdf|archive-date=13 May 2021|access-date=18 May 2021|work=The World Anti-Doping Code|publisher=World Anti-Doping Agency (WADA)}} It is used as an adjuvant, adulterant, and diluent to street drugs such as cocaine and heroin.{{cite web | url = http://www.justice.gov/archive/ndic/pubs2/2580/heroin.htm | publisher = National Drug Intelligence Center | title = New York Drug Threat Assessment | date = November 2002 | url-status = live | archive-url = https://web.archive.org/web/20120812004029/http://www.justice.gov/archive/ndic///pubs2/2580/heroin.htm | archive-date = 12 August 2012 }} It is one of the three common ingredients in site enhancement oil used by bodybuilders.{{cite journal | vauthors = Pupka A, Sikora J, Mauricz J, Cios D, Płonek T | title = [The usage of synthol in the body building] | journal = Polimery W Medycynie | volume = 39 | issue = 1 | pages = 63–5 | date = 2009 | pmid = 19580174 }}

Lidocaine is often added to cocaine as a diluent.{{cite journal | vauthors = Bernardo NP, Siqueira ME, De Paiva MJ, Maia PP | title = Caffeine and other adulterants in seizures of street cocaine in Brazil |year=2003 | journal = International Journal of Drug Policy | volume = 14 | issue = 4 | pages = 331–4 | doi = 10.1016/S0955-3959(03)00083-5 }}{{cite web | url = https://bulk.resource.org/courts.gov/c/F2/599/599.F2d.635.78-5314.html | title = UNITED STATES of America, Plaintiff-Appellee, v. Luis A. CUELLO, Alvaro Bastides-Benitez, John Doe, a/k/a Hugo Hurtado, and Alvaro Carvajal, Defendants-Appellants | date = 25 July 1979 | work = Docket No. 78-5314 | publisher = United States Court of Appeals, Fifth Circuit | url-status = dead | archive-url = https://web.archive.org/web/20120524141840/http://bulk.resource.org/courts.gov/c/F2/599/599.F2d.635.78-5314.html | archive-date = 24 May 2012 }} Cocaine and lidocaine both numb the gums when applied. This gives the user the impression of high-quality cocaine when in actuality the user is receiving a diluted product.{{cite news| vauthors = Winterman D |title=How cutting drugs became big business|url=https://www.bbc.com/news/magazine-11177126|publisher=BBC News Magazine|access-date=20 January 2017|url-status=live|archive-url=https://web.archive.org/web/20170202020256/http://www.bbc.com/news/magazine-11177126|archive-date=2 February 2017|work=BBC News Online|date=7 September 2010}}

• Japanese Pharmacopoeia 15
• United States Pharmacopeia 31{{cite web |url=http://www.usp.org/usp-nf/official-text/accelerated-revision-process/accelerated-revision-history/lidocaine-and-prilocaine-cream-revision-related |title=Revision Bulletin: Lidocaine and Prilocaine Cream–Revision to Related Compounds Test |date=30 November 2007 |publisher=The United States Pharmacopeial Convention |url-status=live |archive-url=https://web.archive.org/web/20130501222459/http://www.usp.org/usp-nf/official-text/accelerated-revision-process/accelerated-revision-history/lidocaine-and-prilocaine-cream-revision-related |archive-date=1 May 2013 }}

{{reflist}}

• {{cite web | title=Lidocaine Transdermal Patch | website=MedlinePlus | url=https://medlineplus.gov/druginfo/meds/a603026.html }}
• {{cite patent |country=US |number=2441498 |status=patent |title=Alkyl glycinanilides |pubdate=1948-05-11 |gdate=1948-05-11 |fdate=1944-07-12 |pridate=1943-07-15 |invent1=Nils Magnus Loefgren |invent2=Bengt Josef Lundqvist |assign1=ASTRA APOTEKARNES KEM FAB |url=https://worldwide.espacenet.com/publicationDetails/biblio?II=1&ND=3&adjacent=true&locale=en_EP&FT=D&date=19480511&CC=US&NR=2441498A&KC=A }}{{Dead link|date=March 2025 |bot=InternetArchiveBot |fix-attempted=yes }}

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Category:Acetamides

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Category:Chemical substances for emergency medicine

Category:Drugs developed by AstraZeneca

Category:Diethylamino compounds

Category:Local anesthetics

Category:Sodium channel blockers

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