Chemocain

Approved Indications:

• Local anesthesia for infiltration, nerve block, epidural, spinal, and caudal anesthesia.
• Topical anesthesia of mucous membranes (e.g., oral, laryngeal, nasal, and urethral).
• Relief of pain associated with postherpetic neuralgia (transdermal patch).
• Ventricular arrhythmias, especially after myocardial infarction (IV formulation only).

Off-label / Clinically Accepted Uses:

• Peripheral neuropathic pain (e.g., diabetic neuropathy) via topical formulations.
• Chronic pain syndromes (topical or IV in select cases).
• Procedural pain in minor dermatologic interventions.

Adults:

• Infiltration Anesthesia:
  0.5% to 1% lidocaine HCl solution; maximum dose: 4.5 mg/kg (not to exceed 300 mg).
• Nerve Block:
  1% to 2% solution; maximum single dose: 300 mg. Repeated doses should not exceed total 500 mg over 24 hours.
• Epidural Anesthesia:
  Initial dose: 1.5% lidocaine HCl, 5–10 mL. Total: up to 300 mg.
• IV (for Ventricular Arrhythmias):
  Initial bolus: 1–1.5 mg/kg over 2–3 minutes; followed by 1–4 mg/min continuous infusion.
• Topical (gel/cream):
  Apply 2–3 times daily on affected skin; max dose depends on formulation.

Pediatrics:

• Topical: Use with caution. For mucosal application, the dose should not exceed 4.5 mg/kg.
• Parenteral use (nerve block or infiltration): Only under specialist guidance, with weight-based calculation.

Elderly & Hepatic/Renal Impairment:

• Use lower end of dosage range.
• Monitor closely due to prolonged elimination half-life.

Route of Administration:

• Intravenous, subcutaneous, intramuscular, topical, transdermal, mucosal, and regional routes (e.g., spinal, epidural, nerve block).

Lidocaine Hydrochloride is a class 1b antiarrhythmic and amide-type local anesthetic. It blocks voltage-gated sodium channels (Na⁺ channels) in neuronal membranes, thereby inhibiting nerve impulse conduction and producing local anesthesia. In the heart, it shortens the action potential duration and refractory period in ventricular myocardial cells, helping to suppress automaticity and reduce ectopic pacemaker activity, making it effective in treating ventricular arrhythmias.

• Absorption: Rapid from injection sites or mucous membranes; bioavailability depends on route.
• Distribution: Widely distributed; crosses blood-brain and placental barriers; protein binding ~60–80%.
• Metabolism: Hepatic via CYP1A2 and CYP3A4 to active and inactive metabolites.
• Excretion: Renal (~90% as metabolites); less than 10% unchanged.
• Onset of Action:
• Topical: 1–5 minutes
• IV: 45–90 seconds
• Infiltration: 2–5 minutes
• Duration of Action:
• IV: 10–20 minutes
• Local anesthesia: 30–60 minutes
• Half-life: 1.5 to 2 hours (may increase in hepatic dysfunction)

• Pregnancy: FDA Category B
  No evidence of teratogenicity in animal studies. Use during pregnancy only if clearly needed and benefits outweigh risks.
• Lactation:
  Excreted in small amounts in breast milk. Generally considered safe during breastfeeding when used at therapeutic doses. Monitor infant for signs of toxicity (e.g., irritability, poor feeding).

• Primary: Local Anesthetic (Amide type)
• Secondary: Class 1b Antiarrhythmic Agent

• Known hypersensitivity to lidocaine or other amide-type anesthetics
• Severe sinoatrial, atrioventricular, or intraventricular block (in absence of pacemaker)
• Severe hepatic dysfunction (relative)
• Porphyria (local anesthesia may trigger attacks)

• Caution in patients with:
• Hepatic or renal impairment
• Heart block or severe bradycardia
• History of seizures
• Risk of methemoglobinemia with excessive topical use
• Systemic toxicity (CNS or cardiovascular) can occur with overdose or inadvertent intravascular administration
• Monitor cardiac rhythm during IV infusion
• Avoid high-dose use in infants and small children
• Perform resuscitation readiness during parenteral administration

Common:

• CNS: Dizziness, lightheadedness, drowsiness
• Dermatologic: Local erythema, burning or stinging sensation (topical use)
• Cardiovascular: Hypotension, bradycardia (IV use)

Serious/Rare:

• Seizures
• Respiratory depression
• Cardiac arrest
• Methemoglobinemia (especially in infants)
• Allergic reactions (e.g., rash, pruritus, anaphylaxis)

• Major:
• Beta-blockers, cimetidine: May increase lidocaine plasma levels via reduced hepatic metabolism.
• Amiodarone: Increased risk of QT prolongation or bradycardia.
• Other antiarrhythmics: Additive cardiac depressant effects.
• Phenytoin: May reduce or potentiate lidocaine effects.
• CYP Enzymes:
• Primarily metabolized by CYP1A2 and CYP3A4
• CYP3A4 inhibitors (e.g., ketoconazole) increase levels
• CYP inducers (e.g., rifampin) may decrease effectiveness
• Alcohol: CNS depressant effects may be additive

• FDA warning update (Topical Forms): Avoid excessive or prolonged use in infants due to methemoglobinemia risk.
• New labeling clarifies that IV formulations are not interchangeable with topical forms due to dosing risks.
• WHO essential medicines list: Lidocaine is included as a core local anesthetic and antiarrhythmic.

• Temperature: Store between 20°C to 25°C (68°F to 77°F)
• Protection: Keep away from excessive heat and light
• Handling Precautions: Do not freeze; protect from contamination
• Injection Forms: Inspect visually for particulate matter before use
• Topical Gels/Creams: Close cap tightly and store as directed (generally at room temperature)