LIDOCAINE HYDROCHLORIDE U.S.P. 2% _ Injection/Solution for

What is LIDOCAINE HYDROCHLORIDE U.S.P. 2% _

LIDOCAINE HYDROCHLORIDE U.S.P. 2% is a sterile injectable solution formulated for local or regional anesthesia. It contains 20 mg of lidocaine hydrochloride per mL (a 2% concentration) and is supplied in a 20 mL plastic vial. This formulation is typically used in minor surgical procedures, dental anesthesia, and as a nerve block agent for pain management or diagnostic procedures.

• Generic Name: Lidocaine Hydrochloride
• Concentration: 20 mg/mL (2%)
• Form: Injectable solution
• Volume: 20 mL plastic vial
• Use: Local or regional anesthesia, nerve blocks, infiltration, minor procedures

Lidocaine is classified as an amide-type local anesthetic. It works by reversibly blocking voltage-gated sodium channels in neuronal membranes. This action prevents the generation and conduction of nerve impulses, thereby causing a temporary loss of sensation in the targeted area.

The 2% solution provides a higher concentration, making it suitable for use in procedures requiring more profound or prolonged anesthesia compared to 1% formulations. It is especially effective in dental blocks, epidurals, and procedures involving deeper tissue layers.

It is essential that LIDOCAINE HYDROCHLORIDE U.S.P. 2% is administered only by trained medical professionals, as improper use can lead to systemic toxicity or adverse effects. The product should be used with caution in patients with known sensitivity to amide anesthetics, those with hepatic dysfunction, or cardiac conduction abnormalities.

This preparation should be clear and colorless when drawn from the vial. If discoloration, turbidity, or particulate matter is observed, the vial should not be used. Always follow proper aseptic techniques during administration and monitor the patient throughout the procedure.

How to use LIDOCAINE HYDROCHLORIDE U.S.P. 2% _

LIDOCAINE HYDROCHLORIDE U.S.P. 2% should be administered by healthcare professionals trained in local and regional anesthesia techniques. The 2% concentration delivers 20 mg of lidocaine per mL, making it potent and effective for deeper or longer procedures.

• Route of Administration: Local infiltration, peripheral nerve block, epidural, or intravenous regional anesthesia (with caution)
• Preparation: Use aseptic technique. Inspect the vial for clarity and expiration date. Do not use if the solution is discolored or contains particulates.
• Dose Calculation: Calculate the dose based on patient weight and intended procedure. Use the minimum dose required to achieve anesthesia.
• Technique: Slowly inject after aspiration to avoid accidental intravascular administration. Monitor patient during and after administration.
• Repeat Dosing: Additional dosing may be needed for longer procedures but should not exceed maximum safe dosage.

Due to the higher concentration (2%), this formulation is generally used when a more intense or longer-lasting block is required. It is often selected for dental blocks, major infiltration procedures, or epidural anesthesia when epinephrine is added to prolong duration. Always monitor for signs of systemic toxicity, especially when administering large volumes or injecting into vascular areas.

Mode of Action LIDOCAINE HYDROCHLORIDE U.S.P. 2% _

Lidocaine exerts its anesthetic action by blocking voltage-gated sodium channels in the neuronal cell membranes. This prevents the initiation and conduction of nerve impulses, resulting in localized loss of sensation.

• Target: Neuronal voltage-gated sodium channels
• Effect: Inhibits sodium ion influx → membrane stabilization → blocked nerve impulse transmission
• Onset: Rapid (1–5 minutes), depending on injection site
• Duration: 1–3 hours, may be prolonged with epinephrine

The 2% formulation provides a higher concentration of active drug, ensuring a more profound nerve blockade, especially useful in areas requiring deeper anesthesia. The onset and duration depend on the tissue vascularity and whether vasoconstrictors are co-administered.

At therapeutic concentrations, the drug affects only the nerve fibers in the localized region. However, excessive dosing or intravascular injection can lead to systemic effects on the central nervous and cardiovascular systems, manifesting as sedation, seizures, or cardiac depression. Thus, proper administration and monitoring are critical.

LIDOCAINE HYDROCHLORIDE U.S.P. 2% _ Interactions LIDOCAINE HYDROCHLORIDE U.S.P. 2% _

Lidocaine may interact with other medications, altering its metabolism or enhancing its effects, especially when administered systemically or in high doses. Understanding these interactions helps minimize adverse outcomes.

• CYP450 Inhibitors (e.g., Cimetidine): Can reduce lidocaine metabolism, increasing plasma levels and risk of toxicity.
• Beta-Blockers: May decrease hepatic blood flow, slowing lidocaine clearance.
• Antiarrhythmic Drugs (e.g., Amiodarone, Mexiletine): Can cause additive cardiac effects and increased risk of bradycardia or hypotension.
• Other Local Anesthetics: Concurrent use may increase total anesthetic load, raising toxicity risk.
• Phenytoin & Barbiturates: May induce or inhibit lidocaine metabolism depending on chronic use and dosage.

Before administering lidocaine, always obtain a comprehensive medication history and assess liver and cardiac function, especially if large doses are required. Caution is advised in elderly patients or those on multiple medications that affect hepatic enzymes.

Dosage of LIDOCAINE HYDROCHLORIDE U.S.P. 2% _

Dosage must be tailored to the patient’s age, weight, clinical condition, and the nature of the procedure. The 2% solution contains 20 mg/mL, which must be carefully calculated to avoid exceeding toxic plasma concentrations.

• Maximum Adult Dose (without epinephrine): 4.5 mg/kg (up to 300 mg = 15 mL of 2% solution)
• Maximum Adult Dose (with epinephrine): 7 mg/kg (up to 500 mg = 25 mL of 2% solution)
• Pediatric Dose: Typically 1–4 mg/kg, individualized per child

Examples of typical volume use for procedures:

• Minor infiltration: 1–5 mL
• Dental block: 1–3 mL
• Peripheral nerve block: 5–20 mL
• Epidural: Up to 20 mL with careful monitoring

Always aspirate before injection and inject slowly. Use the lowest effective dose to achieve anesthesia and reduce the risk of systemic toxicity. Repeat injections should be carefully spaced and monitored.

Possible side effects of LIDOCAINE HYDROCHLORIDE U.S.P. 2% _

While lidocaine is generally safe when used correctly, it may cause localized or systemic side effects. The 2% solution, due to its higher potency, requires extra caution to avoid exceeding toxic thresholds.

• Local Effects:
  • Injection site pain or burning
  • Swelling, redness, or bruising
  • Transient numbness or tingling
• CNS Effects:
  • Drowsiness, dizziness, confusion
  • Restlessness, muscle twitching
  • In severe cases: seizures or loss of consciousness
• Cardiovascular Effects:
  • Bradycardia, hypotension
  • Arrhythmias
  • In rare situations: cardiac arrest

Rarely, hypersensitivity reactions such as rash, pruritus, or anaphylaxis may occur. Immediate cessation and treatment are required if systemic symptoms appear. Lidocaine systemic toxicity (LAST) is a medical emergency and may require lipid emulsion therapy and supportive care.

LIDOCAINE HYDROCHLORIDE U.S.P. 2% _ Contraindications LIDOCAINE HYDROCHLORIDE U.S.P. 2% _

Lidocaine 2% injection is contraindicated in several clinical conditions where the risks outweigh the benefits or where administration could cause harm.

• Hypersensitivity: To lidocaine or other amide-type anesthetics
• Severe Heart Block: Especially without a pacemaker, due to risk of complete conduction block
• Severe Liver Disease: Impaired metabolism increases risk of systemic toxicity
• Infection at Injection Site: May cause spread of infection or inadequate anesthesia
• Porphyria: Lidocaine may trigger acute attacks

Use caution in patients with respiratory depression, low cardiac output, or those taking medications affecting cardiac conduction or liver enzyme metabolism. Always assess risk before using lidocaine in high-risk populations.

Storage of LIDOCAINE HYDROCHLORIDE U.S.P. 2% _

Proper storage maintains the safety, efficacy, and sterility of the lidocaine 2% solution. Follow these guidelines for optimal handling:

• Temperature: Store at 20°C to 25°C (68°F to 77°F)
• Protection: Keep away from light; store in original packaging
• Do Not Freeze: Freezing can damage the integrity of the solution
• Inspect Before Use: Ensure solution is clear, colorless, and free from particulates
• Multi-Dose Use: If reused, follow facility guidelines on contamination control and discard after 24 hours

Always follow institutional policies for disposal of unused solution and sharps. Keep out of reach of children and store securely in a clinical environment to prevent unauthorized access or misuse.