Locaine2%

Locaine is an amide-type local anesthetic agent with the following approved and evidence-supported uses:

Established / FDA-approved uses

• Local infiltration anesthesia for minor surgical and dental procedures.
• Peripheral nerve blocks (e.g. brachial plexus, intercostal, pudendal blocks) for regional anesthesia.
• Sympathetic nerve blocks.
• Epidural and caudal anesthesia for surgical and obstetric procedures.
• Retrobulbar and other regional ophthalmic blocks (by trained specialists).
• Topical/surface anesthesia of accessible mucous membranes and skin (e.g. before minor procedures, to relieve pain from minor skin conditions or mucosal irritation), using appropriate topical formulations.
• Intravenous Locaine is indicated for the acute management of life-threatening ventricular arrhythmias, such as those occurring during acute myocardial infarction, cardiac surgery, or cardiac catheterization.

Guideline-supported / adjunct use

• Use as part of Advanced Cardiac Life Support (ACLS) protocols as an alternative antiarrhythmic for shock-refractory ventricular fibrillation/pulseless ventricular tachycardia when amiodarone is unavailable or ineffective.

The specific formulation, strength, and route of Locaine used depend on the indication and must be selected by a qualified physician or dentist.

Each formulation contains Lidocaine Hydrochloride as the active pharmaceutical ingredient. Depending on the product, it is available as:

• Injectable solutions of various strengths (e.g. 0.5%, 1%, 1.5%, 2%), with or without epinephrine, for infiltration and nerve block anesthesia.
• An intravenous solution/premixed infusion for antiarrhythmic use.
• Topical preparations (gel, ointment, spray, viscous oral solution, or transdermal patch) of varying concentrations for surface anesthesia.

Excipients vary by formulation (e.g. sodium chloride, preservatives, pH-adjusting agents) and are listed on individual product labeling.

Locaine is a synthetic amino-amide compound that acts as a local anesthetic and, when given intravenously, as a Class Ib antiarrhythmic agent. It has been in clinical use for decades and is one of the most widely used local anesthetics worldwide because of its rapid onset, intermediate duration of action, and favorable safety profile when used at recommended doses.

Locaine is used to produce reversible loss of sensation in a localized area of the body (for surgical, dental, or diagnostic procedures) or, in its intravenous form, to suppress dangerous ventricular arrhythmias in emergency cardiac care.

Local Anesthetic (Amide-type); Class Ib Antiarrhythmic Agent. Locaine belongs to this therapeutic class.

Mechanism of action

Lidocaine Hydrochloride blocks voltage-gated sodium channels in neuronal cell membranes, stabilizing the membrane and reducing the influx of sodium ions required for the initiation and conduction of nerve impulses. This produces a reversible, localized loss of sensation (local anesthesia).

When given intravenously, Lidocaine Hydrochloride preferentially blocks sodium channels in depolarized or ischemic cardiac (Purkinje and ventricular) tissue, shortening the action potential duration and effective refractory period, suppressing spontaneous ventricular automaticity, and thereby reducing ventricular ectopy and arrhythmias — its Class Ib antiarrhythmic action.

Pharmacokinetics

• Onset: Rapid — usually within a few minutes for infiltration/nerve block; almost immediate for IV administration.
• Duration: Intermediate (approximately 30–120 minutes for local anesthesia depending on site, dose, and whether combined with epinephrine).
• Metabolism: Extensively metabolized in the liver (primarily via CYP1A2 and CYP3A4) to active and inactive metabolites.
• Elimination: Renal excretion of metabolites; less than 10% excreted unchanged in urine.
• Half-life: Approximately 1.5–2 hours in adults with normal hepatic function; prolonged in hepatic impairment, heart failure, and in neonates.

Locaine is administered by injection (local infiltration, nerve block, epidural/caudal, or intravenous) or applied topically to skin or mucous membranes, strictly according to product labeling and by or under the supervision of a qualified healthcare professional. Intravascular injection must be avoided during local/regional anesthesia (aspirate before injecting); intravenous use for arrhythmias requires cardiac monitoring. Do not use solutions that are discolored or contain particulate matter.

The following interactions with Locaine are clinically significant:

• Other local anesthetics or structurally related amide-type agents: Concurrent use increases the risk of additive systemic toxicity; cumulative doses should be carefully calculated.
• Class I and Class III antiarrhythmic drugs (e.g. amiodarone, mexiletine, tocainide): Concomitant use with intravenous Locaine may have additive cardiac depressant effects and should be used with caution and monitoring.
• CYP1A2/CYP3A4 inhibitors (e.g. cimetidine, certain beta-blockers such as propranolol): These can reduce the hepatic clearance of Locaine, raising plasma levels and increasing the risk of systemic toxicity, particularly with intravenous use.
• Drugs that reduce hepatic blood flow (e.g. beta-blockers, cimetidine): May reduce clearance of intravenous Locaine, requiring dose adjustment.

Inform your physician of all medicines, including over-the-counter drugs and supplements, being used before Locaine is administered.

Side effects of Locaine depend on the dose, route of administration, and whether absorption is local or systemic.

Local reactions

• Pain, burning, or stinging at the injection/application site.
• Localized edema or, rarely, true allergic contact reaction.

Systemic reactions (more likely with high dose, intravenous use, or inadvertent intravascular injection)

• Central nervous system: Lightheadedness, dizziness, perioral/tongue numbness, tinnitus, blurred vision, tremors, drowsiness, confusion, and, at high levels, seizures.
• Cardiovascular: Hypotension, bradycardia, arrhythmias, myocardial depression, and, at toxic levels, cardiovascular collapse or cardiac arrest.
• Rare: Methemoglobinemia (more common in infants and with high or repeated topical doses), true allergic/anaphylactic reactions.

These systemic effects represent local anesthetic systemic toxicity (LAST) and require immediate medical attention (see Overdose Effects).

Pregnancy: Locaine should be used during pregnancy only if clearly needed and if the potential benefit justifies the potential risk to the fetus. It readily crosses the placenta; use in obstetric anesthesia should be limited to the doses required and performed by trained personnel. Consult a physician before use during pregnancy.

Lactation: Locaine is excreted in small amounts in breast milk. It is generally considered acceptable for use during breastfeeding at recommended doses, but a physician should be consulted, particularly for repeated or high-dose use.

Locaine should be administered only by, or under the supervision of, personnel trained in the diagnosis and management of dose-related toxicity and other emergencies that may arise from its use, with resuscitative equipment and drugs immediately available.

• Use with caution in patients with severe hepatic disease, since they are at greater risk of developing toxic plasma concentrations due to reduced ability to metabolize Locaine.
• Use with caution in patients with heart failure, bradycardia, severe shock, or heart block, given the cardiac depressant potential of Locaine, particularly with intravenous use.
• Careful aspiration before injection is required for local/regional techniques to avoid inadvertent intravascular administration.
• Use with caution in debilitated, elderly, or acutely ill patients, and reduce dose accordingly.
• Frequent, high-dose, or prolonged topical use (e.g. viscous oral solution) should be avoided, especially in children, because of the risk of systemic toxicity and methemoglobinemia. See Contraindications for hypersensitivity and cardiac conduction contraindications.

Overdose or excessive systemic absorption of Locaine (local anesthetic systemic toxicity, or LAST) is a medical emergency. Early symptoms may include perioral numbness, tinnitus, dizziness, and restlessness, progressing to seizures, loss of consciousness, respiratory depression, cardiac arrhythmias, and cardiovascular collapse.

If overdose or signs of systemic toxicity are suspected, seek immediate medical attention or contact emergency services/poison control right away. Treatment must be provided in a facility with resuscitative capability; do not attempt to manage suspected Locaine toxicity at home.

Store at room temperature (below 30°C), away from light and moisture. Do not freeze. Do not use if the solution is discolored or contains particulate matter. Keep out of reach of children.

Pediatric patients

Locaine may be used in children with doses reduced according to age, weight, and physical condition; the maximum safe dose (mg/kg) must not be exceeded. Infants and young children are at higher risk of systemic toxicity and methemoglobinemia, particularly with topical/viscous formulations; such use should be closely supervised. Locaine-containing viscous oral solutions should not be used for teething pain in infants and young children due to reports of serious harm.

Elderly patients

Elderly patients, particularly those who are debilitated or have cardiac, hepatic, or renal impairment, generally require reduced doses and closer monitoring, as they are more susceptible to systemic toxicity.

Hepatic impairment

Patients with severe hepatic disease are at increased risk of developing toxic plasma concentrations of Locaine because of reduced metabolic clearance; reduced doses and monitoring are required, especially with intravenous use.

Renal impairment

Dose adjustment is generally not required for local anesthetic use in renal impairment, though accumulation of metabolites may occur with repeated intravenous dosing; monitor accordingly.

Cardiac disease

Patients with heart failure, bradyarrhythmias, or heart block require caution and dose reduction, as described in Precautions and Warnings.

The duration of use of Locaine depends entirely on the clinical indication: local/regional anesthesia is typically single-dose or short-duration for the length of a procedure (approximately 30–120 minutes of effect); intravenous antiarrhythmic infusions are continued only as long as needed to control acute ventricular arrhythmia, generally for a limited period (hours) under continuous cardiac monitoring, and are not intended for long-term or maintenance therapy. Topical formulations should be used only as long as directed by a physician for the specific condition being treated.

Lidocaine Hydrochloride belongs to the amide-type local anesthetic drug class and, for intravenous use, the Class Ib antiarrhythmic drug class.

Lidocaine Hydrochloride blocks voltage-gated sodium channels on neuronal cell membranes, preventing the generation and conduction of nerve impulses and thereby producing reversible local anesthesia; intravenously, it preferentially suppresses abnormal ventricular automaticity by the same sodium-channel-blocking mechanism, giving it Class Ib antiarrhythmic activity. See Pharmacology for full detail.

Category B (FDA legacy pregnancy category)

Locaine is used in pediatric patients for local/regional anesthesia and, in emergency cardiac care, for acute ventricular arrhythmias, with doses carefully calculated by weight and age. Safety and efficacy of some specific formulations (e.g. certain topical products) have not been established in neonates and very young infants, who are at increased risk of methemoglobinemia and systemic toxicity due to immature drug-metabolizing pathways; such use requires close physician supervision. Locaine viscous oral solution should not be used for teething pain in infants and young children. See Use in Special Populations for further detail.