Lidocaine Injection is used:

• As a local anaesthetic for infiltration block and intravenous regional analgesia.
• For the prevention and management of ventricular tachyarrhythmias.

Lidocaine Injection is a sterile, non-pyrogenic aqueous solution containing lidocaine hydrochloride. It is an amide-type local anesthetic with a rapid onset and intermediate duration of action. The onset of action is approximately 5 minutes for infiltration anesthesia and up to 20 minutes for regional anesthesia. The duration of action is about one hour. Lidocaine works by stabilizing neuronal membranes and blocking ionic movement necessary for the initiation and conduction of nerve impulses, thereby producing a local anesthetic effect.

Lidocaine primarily acts by blocking sodium ion influx through voltage-gated sodium channels in neuronal cell membranes. This inhibition prevents the generation and conduction of action potentials, thereby interrupting nerve signal transmission. The drug binds more effectively to sodium channels in their activated state, resulting in faster onset of nerve blockade, particularly in rapidly firing neurons. This mechanism is known as state-dependent blockade.

The dosage is adjusted according to the response of the patient and site of administration.

Adult: For healthy adults, the maximum individual dose should not exceed 4.5mg/kg of body weight and in general it is recommended that the maximum total dose not exceed 300 mg. Recommended doses given in the below serve only as a guide to the amount of anaesthetic required for most routine procedures.

Infiltration-

• Percutaneous: Total dose 5–300 mg
• Intravenous regional: Total dose 50–300 mg

Peripheral Nerve Blocks-

• Brachial: Total dose 225–300 mg
• Dental: Total dose 20–100 mg
• Intercostal: Total dose 30 mg
• Paravertebral: Total dose 30–50 mg

Pudendal (each side):

• Paracervical Obstetrical analgesia: Total dose 100 mg

Sympathetic Nerve Blocks

• Cervical: Total dose 50 mg
• Lumbar: Total dose 50–100 mg

Central Neural Blocks

• Epidural: Total dose 200–300 mg [Dose determined by number of dermatomes to be anesthetized (2–3 mL/dermatome) periodically.]
• Thoracic: Total dose 200–300 mg

Lumbar

• Analgesia: Total dose 250–300 mg
• Anesthesia: Total dose 200–300 mg

Caudal

• Obstetrical analgesia: Total dose 200–300 mg
• Surgical anesthesia: Total dose 225–300 mg.

Administration

Antiarrhythmic treatment: An intravenous dose of 1 mg.kg⁻¹ may be given over 2 min and repeated after 5 min, but giving an infusion of 2–4 mg.min⁻¹ to produce a plasma level of 2–4 mg.l⁻¹ is a more satisfactory technique. To avoid a long delay in achieving a steady state, a loading dose of approximately 1 mg.kg⁻¹ is usually given intravenously over 2 min at the outset.

Cimetidine may reduce the metabolism of lidocaine absorbed into the bloodstream, leading to delayed elimination and an increased risk of adverse effects. Concurrent use with beta-blockers such as propranolol, metoprolol, or nadolol may significantly increase plasma concentrations of lidocaine. Lidocaine may also prolong the duration of action of suxamethonium.

Lidocaine is contraindicated in patients with known hypersensitivity to amide-type local anesthetics.

Adverse reactions are uncommon and usually occur due to high plasma levels resulting from accidental intravascular injection, excessive dosing, rapid absorption, or hypersensitivity. Central nervous system effects may include nervousness, dizziness, blurred vision, tremors, followed by drowsiness, seizures, unconsciousness, and possible respiratory arrest. Cardiovascular effects may include hypotension, myocardial depression, bradycardia, and in severe cases, cardiac arrest. Allergic reactions are rare but may include skin rash, urticaria, edema, or anaphylactoid reactions.

Although animal studies have not demonstrated any harmful effects on the foetus, as with all medications, it should not be used during early pregnancy unless the expected benefits outweigh the potential risks. Caution is advised when administering to breastfeeding women.

Lidocaine for infiltration and nerve block should be administered only by clinicians experienced in the diagnosis and management of dose-related toxicity. The safety and efficacy of lidocaine depend on appropriate dosing, correct administration technique, necessary precautions, and preparedness for emergency situations. Standard medical references should be consulted for specific techniques and precautions related to various regional anaesthetic procedures. Resuscitation equipment, oxygen, and emergency medications must be readily available for immediate use.

Lidocaine should be used with caution in patients with epilepsy, impaired cardiac conduction, bradycardia, compromised respiratory function, and hepatic impairment, especially when the dose or site of administration may lead to elevated blood concentrations. The effectiveness of local anaesthetics may be reduced when injected into inflamed or infected tissues. Repeated administration of lidocaine may result in a significant rise in blood levels due to gradual accumulation of the drug or its metabolites. Patient tolerance to increased blood levels may vary depending on their clinical condition. Continuous and careful monitoring of cardiovascular and respiratory vital signs, along with the patient’s level of consciousness, should be maintained after each injection of a local anaesthetic.

In children, doses should be adjusted according to age, body weight, and physical condition. Elderly patients may be more sensitive to systemic effects and may require lower doses.

Local and surface anesthetic

Store below 25°C, protected from light and moisture. Keep out of reach of children.