lidocaine (lignocaine)
Xylocaine

lidocaine hydrochloride
Anestacon, Dilocaine, L-Caine, Lidoderm Patch, Lidoject, LidoPen Auto-Injector, Nervocaine, Xylocaine, Xylocaine Viscous, Zilactin-L

Available forms
Available by prescription only
Injection: 5 mg/ml, 10 mg/ml, 15 mg/ml, 20 mg/ml, 40 mg/ml, 100 mg/ml, 200 mg/ml
Jelly: 2%
Ointment: 5%
Parenteral injection: 0.5%, 1%, 1.5%, 2%, 4% (lidocaine with epinephrine combinations also available)
Premixed solutions: 2 mg/ml, 4 mg/ml, 8 mg/ml in D₅W
Spray: 10%
Topical solution: 2%, 4%
Cream: 0.5%
Gel: 0.5%, 2.5%
Liquid: 2.5%
Ointment: 2.5%
Spray: 0.5%
Transdermal patch: 5%

Indications and dosages
 Ventricular arrhythmias from MI, cardiac manipulation, or cardiac glycosides. Adults: 50 to 100 mg I.V. bolus given at 25 to 50 mg/ minute. If no clinical response, repeat bolus after 5 minutes. Don’t exceed 300-mg total bolus during a 1-hour period. Simultaneously, begin continuous infusion of 1 to 4 mg/ minute. If single bolus has been given, repeat smaller bolus (usually one-half initial bolus) 5 to 10 minutes after start of infusion to maintain therapeutic serum level. After 24 hours of continuous infusion, decrease rate by one half.
Elderly patients: Give a reduced bolus amount and use slower infusion rate.
≡ Dosage adjustment. A reduction in amount of bolus dosage may be needed in patients with heart failure or hepatic disease. Use slower infusion rate. For I.M. administration in all adults, 300 mg (4.3 mg/kg) in deltoid muscle has been used in early stages of acute MI. If needed, may be repeated in 60 to 90 minutes.
Children: 0.5 to 1 mg/kg by I.V. bolus; may repeat bolus if needed, not to exceed 3 to 5 mg/kg, followed by infusion of 10 to 50 mcg/kg/minute. In advanced cardiac life support, 1 mg/kg I.V. bolus, followed by an infusion of 20 to 50 mcg/kg/minute if needed after defibrillation or cardioversion.
 Status epilepticus ◇. Adults: 1 mg/kg I.V. bolus; then, if seizure continues, administer 0.5 mg/kg 2 minutes after first dose; infusion at 30 mcg/kg/ minute may be used.
 Local anesthesia of skin or mucous membranes, pain from dental extractions, stomatitis. Adults and children: Apply 2% to 5% solution or ointment or 15 ml of Xylocaine Viscous q 3 to 4 hours to oral or nasal mucosa.
 Local anesthesia in procedures involving the male or female urethra. Adults: Instill about 15 ml (male) or 3 to 5 ml (female) into urethra.
 Pain, burning, or itching caused by burns, sunburn, or skin irritation. Adults and children: Apply topical agent liberally.
 Relief of pain caused by postherpetic neuralgia. Adults: Apply 1 to 3 patches to intact skin, covering most painful area, once daily for up to 12 hours each day. Smaller areas of treatment are recommended in patients who are debilitated or have poor elimination. Excessive dosing by applying patch to larger areas or for longer than recommended wearing time could cause increased absorption of lidocaine and high lidocaine levels, leading to serious adverse effects.
 Lidocaine hydrochloride injection used as procedural anesthetic. Adults: Lidocaine with epinephrine, 7 mg/kg (no more than 500 mg total); lidocaine without epinephrine, 4.4 mg/kg (no more than 300 mg total). For continuous epidural or caudal anesthesia, maximum doses shouldn’t be administered at intervals of less than 90 minutes. Maximum recommended dose in paracervical block is 200 mg total. For I.V. regional anesthesia, dose shouldn’t exceed 4 mg/kg.
Children: Dosages are based on age and weight. For I.V. regional anesthesia, use dilute solutions (0.25% to 0.5%) not to exceed 3 mg/kg.
 The suggested concentrations and volumes serve only as a guide. Other volumes and concentrations may be used as long as the total maximum recommended dose isn’t exceeded.
≡ Dosage adjustment. Dosages are reduced for children, geriatric patients, debilitated patients, and patients with cardiac or liver disease.

Recommended dosages Injection (without epinephrine) Procedure Concentration (%) Volume (ml) Total dose (mg) Infiltration Percutaneous 0.5 or 1 1-60 5-300 I.V. regional 0.5 10-60 50-300 Peripheral nerve blocks Brachial 1.5 15-20 225-300 Dental 2 1-5 20-100 Intercostal 1 3 30 Paravertebral 1 3-5 30-50 Pudendal (each side) 1 10 100 Paracervical Obstetrical analgesia (each side) 1 10 100 Sympathetic nerve blocks Cervical (stellate ganglion) 1 5 50 Lumbar 1 5-10 50-100 Central neural blocks Epidural*  Thoracic 1 20-30 200-300  Lumbar   Analgesia 1 25-30 250-300   Anesthesia 1.5 15-20 225-300 2 10-15 200-300 Caudal  Obstetrical analgesia 1 20-30 200-300   Surgical anesthesia 1.5 15-20 225-300 *Dose determined by number of dermatomes to be anesthetized (2-3 ml/dermatome)

Pharmacodynamics
Ventricular antiarrhythmic action: One of the oldest antiarrhythmics, lidocaine remains among the most widely used drugs for treating acute ventricular arrhythmias. As a class IB antiarrhythmic, it suppresses automaticity and shortens the effective refractory period and action potential duration of His-Purkinje fibers and suppresses spontaneous ventricular depolarization during diastole. Therapeutic levels don’t significantly affect conductive atrial tissue and AV conduction.
Unlike quinidine and procainamide, lidocaine doesn’t significantly alter hemodynamics when given in usual doses. Drug seems to act preferentially on diseased or ischemic myocardial tissue; exerting its effects on the conduction system, it inhibits reentry mechanisms and halts ventricular arrhythmias.
Local anesthetic action: As a local anesthetic, lidocaine blocks initiation and conduction of nerve impulses by decreasing the permeability of the nerve cell membrane to sodium ions.

Pharmacokinetics
Absorption: Absorbed after oral administration; however, a significant first-pass effect occurs in the liver and only about 35% of drug reaches systemic circulation. Oral doses high enough to achieve therapeutic blood levels result in an unacceptable toxicity, probably from high levels of lidocaine.
Distribution: Distributed widely throughout the body; it has a high affinity for adipose tissue. After I.V. bolus administration, an early, rapid decline in plasma levels occurs; this is mainly because of distribution into highly perfused tissues, such as the kidneys, lungs, liver, and heart, followed by a slower elimination phase in which metabolism and redistribution into skeletal muscle and adipose tissue occur. The first (early) distribution phase occurs rapidly, calling for a constant infusion after an initial bolus dose. Distribution volume declines in patients with liver or hepatic disease, resulting in toxic levels with usual doses. About 60% to 80% of circulating drug is bound to plasma proteins. Usual therapeutic drug level is 1.5 to 5 mcg/ml. Although toxicity may occur within this range, levels greater than 5 mcg/ml are considered toxic and warrant dosage reduction.
Metabolism: Metabolized in the liver to two active metabolites. Less than 10% of a parenteral dose escapes metabolism and reaches the kidneys unchanged. Metabolism is affected by hepatic blood flow, which may decrease after MI and with heart failure. Liver disease also may limit metabolism.
Excretion: Half-life undergoes a biphasic process, with an initial phase of 7 to 30 minutes followed by a terminal half-life of 1 1/2 to 2 hours. Elimination half-life may be prolonged in patients with heart failure or liver disease. Continuous infusions of longer than 24 hours also may cause a half-life increase.

Contraindications and precautions
Contraindicated in patients hypersensitive to amide-type local anesthetics, Stokes-Adams syndrome, Wolff-Parkinson-White syndrome, and severe degrees of SA, AV, or intraventricular block in absence of artificial pacemaker. Also contraindicated in patients with inflammation or infection in puncture region, septicemia, severe hypertension, spinal deformities, and neurologic disorders.
  Use cautiously in geriatric patients; in patients with renal or hepatic disease, complete or second-degree heart block, sinus bradycardia, or heart failure; and in those who weigh less than 110 lb.

Interactions
Drug-drug. Antiarrhythmics, including phenytoin, procainamide, propranolol, and quinidine: May cause additive or antagonist effects as well as additive toxicity. Avoid use together.
Beta blockers, cimetidine: May cause lidocaine toxicity from reduced hepatic clearance. Avoid use together.
Butyrophenones, phenothiazines: May reduce or reverse the pressor effects of epinephrine. Monitor patient for drug effect.
Cyclic antidepressants, MAO inhibitors: Causes prolonged and severe hypertension when lidocaine with epinephrine is used. Avoid use together.
Ergot-type oxytoxic drugs, vasopressors: Causes severe, persistent hypertension or CVA. Avoid using lidocaine with epinephrine.
High-dose lidocaine, succinylcholine: May increase neuromuscular effects of succinylcholine. Use together cautiously.
Drug-herb. Pareira: May add to or potentiate neuromuscular blockade. Discourage use together.

Adverse reactions
CNS: seizures; anxiety, nervousness, lethargy, somnolence, paresthesia, muscle twitching; confusion, tremor, stupor, restlessness, light-headedness, hallucinations (with systemic form); apprehension, unconsciousness, confusion, tremors, stupor, restlessness, slurred speech, euphoria, depression, light-headedness (with topical use).
CV: bradycardia,CARDIAC ARREST; hypotension, new or worsened arrhythmias (with systemic form); hypotension, myocardial depression, arrhythmias (with topical use); edema, asystole.
EENT: tinnitus, blurred or double vision (with systemic form); tinnitus, blurred or double vision (with topical use).
GI: nausea, vomiting (with topical use).
Respiratory: respiratory arrest, status asthmaticus.
Skin: dermatologic reactions, sensitization; diaphoresis, rash (with topical use).
Other: anaphylaxis; soreness at injection site, sensation of cold (with systemic form).

Effects on lab test results
None reported.

Overdose and treatment
Effects of overdose include signs and symptoms of CNS toxicity, such as seizures or respiratory depression, and CV toxicity (as indicated by hypotension).
 Treatment includes general supportive measures and drug discontinuation. A patent airway should be maintained and other respiratory support measures carried out immediately. Diazepam or thiopental may be given to treat any seizures. To treat significant hypotension, vasopressors (including dopamine and norepinephrine) may be administered.

Special considerations
• Drug has been used investigationally to treat refractory status epilepticus.
• Don’t administer lidocaine with epinephrine (for local anesthesia) to treat arrhythmias. Use solutions with epinephrine cautiously in CV disorders and in body areas with limited blood supply (ears, nose, fingers, toes).
• Patients receiving lidocaine I.M. show a sevenfold increase in serum CK level. Such CK originates in skeletal muscle, not the heart. Test isoenzyme levels to confirm MI, if using I.M. route.
• When larger volumes are required for local anesthesia, use a solution containing epinephrine.
• For I.V. regional anesthesia, use 50 ml Xylocaine 0.5% injection.
• Preparations used for epidural, spinal, or caudal anesthesia should contain no bacteriostatic agents.
• Prepare I.V. infusions by adding 1 g of lidocaine (using 25 ml of a commercially available 4% or 5 ml of a 20% injection) to 1 L of D₅W injection to provide a concentration of 1 mg/ml. Alternatively, 0.2% or 0.4% is available. In fluid-restricted patients, an 8 mg/ml concentration may be used. Don’t add to blood transfusion assemblies.
• In many severely ill patients, seizures may be the first sign of toxicity. However, severe reactions are usually preceded by somnolence, confusion, and paresthesia. Regard all signs and symptoms of toxicity as serious, and promptly reduce dosage or discontinue therapy. Continued infusion could lead to seizures and coma. Give oxygen through nasal cannula, if not contraindicated. Keep oxygen and CPR equipment handy.
• Patient requires constant cardiac monitoring when receiving I.V. lidocaine. Use infusion pump or microdrip system and timer to monitor infusion precisely. Never exceed 4 mg/minute. A faster infusion greatly increases risk of toxicity.
• Monitor vital signs and serum electrolyte, BUN, and creatinine levels.
• Monitor ECG constantly if administering drug I.V., especially in patients with liver disease, heart failure, hypoxia, respiratory depression, hypovolemia, or shock, because these conditions may affect drug metabolism, excretion, or distribution volume, predisposing patient to drug toxicity.
• Monitor patient for signs of excessive depression of cardiac conductivity (such as sinus node dysfunction, PR-interval prolongation, QRS complex widening, and appearance or exacerbation of arrhythmias). If they occur, reduce dosage or discontinue drug.
• Therapeutic serum levels range from 2 to 5 mcg/ml.
• Doses of up to 400 mg I.M. have been advocated in prehospital phase of acute MI.
 ALERT Don’t use solutions containing preservatives for spinal, epidural, or caudal block or I.V. injection.
 ALERT Additive syringes and single-use vials containing 40, 100, or 200 mg/ml are for I.V. infusion preparation and must be diluted before use.
• With epidural use, inject a 2- to 5-ml test dose at least 5 minutes before giving total dose to check for intravascular or subarachnoid injection. Motor paralysis and extensive sensory anesthesia indicate subarachnoid injection.
• Discard partially used vials containing no preservatives.
• Because I.M. lidocaine therapy may increase CK levels, isoenzyme tests should be performed for differential diagnosis of acute MI.
Pediatric patients
• Safety and efficacy in children haven’t been established. Use of an I.M. autoinjector device isn’t recommended.
Geriatric patients
• Because of concurrent disease states and declining organ system function in geriatric patients, use conservative lidocaine doses.

Patient education
• Advise patient to report slowed or abnormal heart rhythms, ringing in the ears, vision changes, difficulty breathing, and confusion.
• Tell patient receiving lidocaine I.M. that drug may cause soreness at injection site.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use