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, non-pyrogenic solution intended for injection, primarily used for producing local or regional anesthesia. Each mL of this solution contains 20 mg of lidocaine hydrochloride, making it suitable for procedures that require deeper or longer-lasting anesthesia. The 50 mL plastic vial format is designed for multiple uses in hospital and clinical settings.

• Generic Name: Lidocaine Hydrochloride
• Concentration: 2% (20 mg/mL)
• Form: Injectable solution
• Volume: 50 mL per vial
• Common Uses: Local infiltration, nerve blocks, epidural anesthesia, intravenous regional anesthesia

Lidocaine belongs to the amide class of local anesthetics. Its role is to block nerve signal conduction by inhibiting sodium ion movement through voltage-gated channels in neuronal membranes. This effect temporarily numbs the area to which it is applied or injected. The 2% concentration is especially effective in situations that demand a stronger block or more extended analgesia compared to 1% solutions.

Due to its potency and systemic absorption potential, lidocaine should only be administered by trained professionals who are familiar with dosage limits, resuscitation protocols, and monitoring techniques. The 50 mL size is typically used in environments where multiple doses are required, such as operating rooms, pain management centers, or dental surgical units.

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

LIDOCAINE HYDROCHLORIDE U.S.P. 2% should only be administered by trained healthcare professionals in a clinical setting. It is used for local or regional anesthesia via injection. This 2% formulation (20 mg/mL) is particularly effective for procedures requiring prolonged or deeper anesthesia.

• Routes of Administration: Local infiltration, peripheral nerve block, epidural anesthesia, and intravenous regional anesthesia (with caution).
• Preparation: Use aseptic technique. Inspect the vial for discoloration or particulates before use. Discard if contamination is suspected.
• Injection Technique: Aspirate before injection to prevent intravascular administration. Inject slowly to minimize systemic absorption.
• Use in Dental or Surgical Settings: Commonly used for nerve blocks or tissue infiltration during minor surgeries or dental procedures.
• Repeat Use: The 50 mL multi-dose vial allows for repeat dosing, but always monitor total cumulative dose to avoid systemic toxicity.

The dosing and technique vary depending on the site of injection, type of block, patient weight, and clinical condition. Continuous monitoring of cardiac and neurological status is essential during administration. Emergency equipment (e.g., oxygen, resuscitation cart, lipid emulsion therapy) must be readily available in case of systemic toxicity or allergic reaction.

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

Lidocaine functions by reversibly blocking voltage-gated sodium channels on the neuronal cell membrane. This action prevents depolarization and inhibits the conduction of nerve impulses, thereby producing a localized anesthetic effect.

• Target: Voltage-gated sodium channels in peripheral neurons.
• Primary Effect: Prevents sodium ion influx → inhibits action potential propagation → loss of sensory input.
• Onset of Action: Typically 2–5 minutes after injection depending on the site.
• Duration of Effect: Generally 60–120 minutes; prolonged if combined with vasoconstrictors such as epinephrine.

The anesthetic effect is localized to the area of administration and does not affect consciousness. Lidocaine's action is concentration-dependent: higher concentrations like 2% provide a more intense and longer-lasting block compared to 1%. Its rapid onset makes it particularly useful in emergency settings or short-duration surgical procedures.

However, systemic absorption (especially after intravascular injection) may affect cardiac sodium channels, leading to conduction disturbances. Lidocaine also has a mild antiarrhythmic effect (Class Ib), which is why it is occasionally used in managing ventricular arrhythmias.

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

Although lidocaine is primarily administered locally, systemic absorption may occur, especially with high doses or inadvertent intravenous injection. Lidocaine is metabolized in the liver by cytochrome P450 enzymes (primarily CYP3A4), making it susceptible to interactions with other drugs that induce or inhibit these enzymes.

• CYP3A4 Inhibitors (e.g., erythromycin, ketoconazole): May increase lidocaine plasma concentration, leading to toxicity.
• CYP Inducers (e.g., rifampin, phenytoin): Can reduce the therapeutic efficacy by accelerating metabolism.
• Beta-Blockers (e.g., propranolol): May reduce hepatic blood flow and slow lidocaine clearance, especially in elderly patients.
• Other Antiarrhythmics (e.g., amiodarone): Can cause additive effects on cardiac conduction and should be used with caution.
• Local Anesthetics: Avoid combining multiple local anesthetics without adjusting cumulative dosage to avoid systemic overload.

To minimize interaction risks, assess the patient’s current medication profile, especially if repeated or high-volume lidocaine injections are planned. Monitor patients for signs of central nervous system or cardiovascular side effects when lidocaine is used alongside interacting drugs.

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

Lidocaine dosage must be tailored to each patient based on body weight, the intended procedure, and the patient’s general condition. The goal is to use the lowest effective dose while avoiding toxicity.

• Adult Maximum Dose (without epinephrine): 4.5 mg/kg (up to 300 mg = 15 mL of 2% solution)
• Adult Maximum Dose (with epinephrine): 7 mg/kg (up to 500 mg = 25 mL of 2% solution)
• Children: Typically 1–4 mg/kg (based on weight and clinical scenario)

Example approximate volumes for common procedures:

• Local infiltration: 2–5 mL
• Nerve block: 5–20 mL
• Epidural anesthesia: 10–20 mL

Always aspirate before injection to prevent intravascular administration. Dosage should be adjusted for elderly patients, those with hepatic impairment, or those receiving other CNS depressants. Never exceed the total maximum dose, especially when using multiple injections from a 50 mL vial.

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

Lidocaine is generally well tolerated when administered correctly. However, systemic absorption, overdose, or inadvertent intravascular injection can lead to adverse reactions. These effects can range from mild to life-threatening, especially when the drug enters systemic circulation in high concentrations.

• Common Side Effects:
• Localized redness or swelling at the injection site
• Mild dizziness or lightheadedness
• Numbness extending beyond the target area
• Nervous System Reactions:
• Restlessness, confusion, tremors
• Tinnitus (ringing in the ears)
• Seizures (especially in overdose situations)
• Drowsiness or unconsciousness with high systemic levels
• Cardiovascular Reactions:
• Hypotension (low blood pressure)
• Bradycardia (slow heart rate)
• Arrhythmias or cardiac arrest in severe toxicity
• Allergic Reactions:
• Rash or urticaria (hives)
• Bronchospasm or difficulty breathing
• Anaphylaxis (rare but serious)

Early symptoms of lidocaine toxicity include perioral numbness, metallic taste, tinnitus, and agitation. If any of these appear, stop administration immediately and initiate appropriate treatment. In emergencies, lipid emulsion therapy may be indicated to counteract systemic toxicity.

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

Lidocaine 2% is contraindicated in specific patient populations or clinical situations. It is crucial to screen patients thoroughly before administration to avoid serious complications.

• Known Hypersensitivity: Do not use in patients allergic to lidocaine or other amide-type local anesthetics.
• Severe Hepatic Impairment: Impaired metabolism increases the risk of accumulation and toxicity.
• Heart Block (without pacemaker): Lidocaine may worsen conduction abnormalities.
• Severe Hypovolemia or Shock: Reduced perfusion may potentiate CNS and cardiovascular toxicity.
• Porphyria: Use with caution, as local anesthetics can trigger acute episodes.

Additionally, lidocaine should be used with caution in elderly patients, those with renal impairment, and patients taking medications that alter sodium channel activity. During labor and delivery, monitor fetal heart rate if epidural administration is considered.

Lidocaine should never be injected intravascularly unless used intentionally as an antiarrhythmic under cardiac monitoring. Always aspirate before injection to confirm extravascular placement.

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

Proper storage of LIDOCAINE HYDROCHLORIDE U.S.P. 2% ensures product efficacy and patient safety. As a sterile injectable solution, the 50 mL plastic vial should be maintained under recommended conditions.

• Temperature: Store between 15°C to 30°C (59°F to 86°F).
• Protection from Light: Keep vials in their original carton to protect from light. Avoid prolonged exposure to direct sunlight.
• Freezing: Do not freeze. Freezing may cause crystallization or compromise sterility.
• Multi-Dose Use: Once opened, use within the recommended time (usually within 24 hours) under sterile conditions to avoid contamination.
• Visual Inspection: Do not use the solution if it appears cloudy, discolored, or contains particles.

Always store in a secure environment, away from unauthorized access, especially in clinical or home settings. Check expiration date before use, and dispose of any unused solution according to local pharmaceutical disposal regulations.