Xylocaine (lidocaine hydrochloride) is a premier amide-type local anesthetic agent widely utilized in medical practice for its rapid onset, reliable depth, and controlled duration of action. As a cornerstone of procedural sedation and pain management, it provides effective sensory blockade for a diverse range of clinical interventions, from minor office-based procedures to more complex surgical operations. Its well-established pharmacokinetic profile and extensive safety record make it a first-line choice for healthcare professionals seeking predictable and efficient anesthesia.

Features

• Active Pharmaceutical Ingredient: Lidocaine Hydrochloride
• Available Formulations: Injectable solutions (multiple concentrations: 0.5%, 1%, 2%), Jelly (2%), Ointment (5%), Cream (various), Spray (10%)
• Mechanism of Action: Reversible blockade of voltage-gated sodium channels in neuronal membranes, preventing the initiation and conduction of nerve impulses.
• Onset of Action: Rapid, typically within 2-5 minutes for infiltration anesthesia.
• Duration of Action: Intermediate; approximately 30-60 minutes for infiltration when used without epinephrine. Duration is significantly prolonged with vasoconstrictors like epinephrine.
• Metabolism: Primarily hepatic via cytochrome P450 enzymes (CYP1A2 and CYP3A4) to active (monoethylglycinexylidide) and inactive metabolites.
• Excretion: Renal elimination of metabolites.
• pH-Adjusted Formulations: Certain preparations are buffered to reduce injection-associated stinging.

Benefits

• Provides rapid and predictable onset of anesthesia, minimizing patient wait time and improving procedural workflow efficiency.
• Offers a favorable safety margin with a well-documented and manageable side effect profile when administered correctly and within recommended dosages.
• Demonstrates versatile application across numerous clinical specialties, including dentistry, dermatology, cardiology (as an antiarrhythmic), anesthesiology, and emergency medicine.
• The availability of multiple concentrations and formulations (injectable, topical) allows for tailored anesthesia strategies based on procedural depth, area, and patient-specific factors.
• When combined with a vasoconstrictor like epinephrine, it provides enhanced hemostasis at the surgical site and extends the duration of analgesic effect.
• Serves as a foundational agent for more advanced regional anesthetic techniques, such as nerve blocks and epidural anesthesia, when used at appropriate concentrations.

Common use

Xylocaine is indicated for the production of local anesthesia by infiltration injection, nerve block, and topical application. Its uses are extensive and include:

• Infiltration Anesthesia: Numbing a specific area for minor surgical procedures, laceration repair, and suturing.
• Nerve Blocks: Regional anesthesia for procedures on the fingers, toes, digits, and larger areas like the forearm or lower leg (e.g., Bier block, digital nerve block).
• Topical Anesthesia: Mucous membrane anesthesia for endoscopic procedures (laryngoscopy, bronchoscopy, urethroscopy), catheter insertion, and treatment of painful conditions in the oropharynx. Dermatological procedures such as laser therapy, skin biopsy, and superficial lesion removal.
• Dental Procedures: Infiltration and block anesthesia for restorative work, extractions, and periodontal surgery.
• Cardiac Applications: Intravenous administration for the acute management of ventricular arrhythmias (e.g., ventricular tachycardia, fibrillation).
• Obstetric Anesthesia: As a component of epidural anesthesia for labor and delivery (using specific, preservative-free formulations).

Dosage and direction

Dosage varies significantly based on the anesthetic procedure, the tissue vascularity, the area to be anesthetized, individual patient tolerance, and the specific formulation used. The smallest dose and lowest concentration that provides effective anesthesia should always be employed.

• Maximum Recommended Dose:

  • For healthy adults: 4.5 mg/kg (not to exceed 300 mg) of plain lidocaine.
  • With Epinephrine (1:100,000 to 1:200,000): 7 mg/kg (not to exceed 500 mg).
  • These are general guidelines; always consult official prescribing information for specific formulations.

• Administration Direction:

  1. Aspirate: Before injecting, always aspirate the syringe to ensure the needle tip is not intravascular.
  2. Inject Slowly: Administer the solution slowly while monitoring the patient for any signs of adverse reaction.
  3. Topical Use: Apply the recommended quantity (e.g., 2-5 mL of jelly) to the desired mucous membrane surface using appropriate applicators. Do not apply to large areas of broken or inflamed skin. Specific dosing for cardiac antiarrhythmic use is distinct and based on mg/kg loading and infusion protocols.

Precautions

• Standard Monitoring: Resuscitative equipment, oxygen, and other emergency drugs must be immediately available during any administration.
• Hepatic Impairment: Use with extreme caution and at reduced doses in patients with severe liver disease or reduced hepatic blood flow, as metabolism is impaired, increasing the risk of systemic toxicity.
• Renal Impairment: Use caution; accumulation of metabolites may occur, though their toxic potential is low.
• Elderly and Debilitated Patients: Often require reduced doses due to possible altered pharmacokinetics, coexisting medical conditions, and decreased lean body mass.
• Malignant Hyperthermia: Although not a known triggering agent, use with caution in susceptible patients.
• Methemoglobinemia: Risk is higher with certain metabolites and prilocaine; be aware of symptoms (cyanosis unresponsive to oxygen) especially in susceptible patients (e.g., those with G6PD deficiency).
• Topical Use on Mucous Membranes: Rapid systemic absorption can occur; apply the minimum amount necessary.

Contraindications

• Known hypersensitivity to lidocaine, other amide-type local anesthetics, or any component of the formulation.
• Administration of lidocaine with vasoconstrictors (e.g., epinephrine) is contraindicated for use in areas supplied by end-arteries (e.g., digits, nose, ears, penis) due to the risk of vasoconstriction-induced ischemia and necrosis. (Note: This is a classic teaching, though practice may vary with digital blocks using very dilute epinephrine in specific settings).
• The presence of severe shock or heart block (2nd or 3rd degree) without a functioning pacemaker.
• Intravenous regional anesthesia (Bier Block) is contraindicated in patients with hypertension, peripheral vascular disease, and sickle cell disease.
• Specific formulations (e.g., those containing preservatives) are contraindicated for epidural or spinal anesthesia.

Possible side effect

Adverse reactions are generally dose-related and result from high plasma levels.

• Central Nervous System: Nervousness, dizziness, blurred vision, tremors, drowsiness, convulsions, unconsciousness, respiratory depression and arrest. excitability may be the first sign of toxicity.
• Cardiovascular System: Bradycardia, hypotension, arrhythmias, cardiovascular collapse, and cardiac arrest.
• Allergic Reactions: Though rare (more common with ester-type anesthetics), urticaria, angioedema, bronchospasm, and anaphylaxis can occur.
• Local Reactions: Pain at the injection site, persistent sensory deficit, and rarely, tissue irritation or damage.
• Other: Tinnitus, metallic taste, nausea, vomiting, and thermoregulatory dysfunction.

Drug interaction

• Other Local Anesthetics: Concomitant use may have additive toxic effects.
• Antiarrhythmics: (e.g., amiodarone, beta-blockers, procainamide) may potentiate myocardial depression.
• CYP450 Inhibitors: Drugs that inhibit CYP1A2 (e.g., fluvoxamine) or CYP3A4 (e.g., ketoconazole, erythromycin, verapamil) may decrease lidocaine metabolism, increasing the risk of toxicity.
• CYP450 Inducers: Drugs like phenobarbital or rifampin may increase metabolism, potentially reducing efficacy.
• Vasoconstrictors: The addition of epinephrine to lidocaine can interact with tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs), potentially leading to severe, prolonged hypertension.
• Succinylcholine: May enhance the neuromuscular blocking effect.

Missed dose

The concept of a “missed dose” is not applicable to Xylocaine, as it is administered as a single procedure-based dose and not on a chronic, scheduled regimen. Anesthesia is provided on an as-needed basis for a specific intervention.

Overdose

Overdose results in systemic toxicity, primarily affecting the central nervous and cardiovascular systems.

• Symptoms:
  • CNS: Initial excitation (restlessness, tremor, convulsions) followed by profound CNS depression (drowsiness, coma, respiratory arrest).
  • CVS: Hypotension, bradycardia, conduction delays, cardiovascular collapse, and asystole.
• Management:
  1. Stop Administration.
  2. Airway Management: Secure and maintain a patent airway. Administer 100% oxygen. Assist ventilation as needed.
  3. Seizure Control: Administer a benzodiazepine (e.g., diazepam, midazolam) IV. Barbiturates or propofol may be used if benzodiazepines are ineffective. Avoid phenytoin.
  4. Cardiovascular Support: Treat hypotension and bradycardia with IV fluids and vasopressors (e.g., epinephrine, norepinephrine). Atropine may be used for bradycardia.
  5. ACLS Protocols: Initiate advanced cardiac life support if cardiac arrest occurs.
  6. Intravenous Lipid Emulsion (ILE) Therapy: ILE (20% lipid emulsion) is a recognized antidote for severe local anesthetic systemic toxicity (LAST). Administer a 1.5 mL/kg bolus followed by a continuous infusion of 0.25 mL/kg/min.

Storage

• Store at controlled room temperature, 20°-25°C (68°-77°F). Avoid excessive heat (above 40°C/104°F) and freezing.
• Protect from light. Store in the original container.
• Keep all medications out of the reach of children and pets.
• Do not use if the solution is discolored or contains particulate matter.

Disclaimer

This information is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any new treatment. Never disregard professional medical advice or delay in seeking it because of something you have read here. The author and publisher are not responsible for any errors or omissions or for any consequences from application of the information in this document.

Reviews

• “As an emergency physician, Xylocaine is my go-to for rapid and reliable local anesthesia. Its predictable onset and efficacy are crucial for efficient wound management. The buffered formulation has significantly reduced patient discomfort during injection.” – Dr. A. Chen, MD
• “In our dental practice, we rely on lidocaine 2% with epinephrine for virtually all procedures. It provides excellent hemostasis and profound anesthesia that lasts for the duration of most treatments. A true workhorse agent.” – Dr. M. Rodriguez, DDS
• “For topical procedures in dermatology, the 2% jelly is indispensable. It allows for painless catheterization and minor interventions on mucous membranes. We carefully calculate the total dose to avoid systemic absorption, especially in pediatric patients.” – RN S. Petrov, Dermatology Clinic
• “While an excellent drug, it demands respect. I have managed one case of LAST from a inadvertent intravascular injection during a nerve block. It was a stark reminder of the importance of aspiration, slow injection, and constant vigilance. Thankfully, the patient recovered fully with prompt lipid therapy.” – Dr. P. Iyer, Anesthesiologist