Usage
Lidocaine with adrenaline is prescribed for local and regional anesthesia. It is indicated for use in adults and children (above a certain age depending on concentration) for various procedures requiring local numbing or pain relief, such as minor surgical procedures, dental work, pain relief during labor, and treatment of certain types of chronic pain. This drug is categorized as a local anesthetic, more specifically, an amide-type local anesthetic combined with a vasoconstrictor. Lidocaine blocks sodium channels, inhibiting nerve impulse transmission, while adrenaline (epinephrine), a vasoconstrictor, prolongs the anesthetic effect by reducing blood flow at the injection site.
Alternate Names
Lidocaine with Epinephrine, Xylocaine with Adrenaline (brand name).
How It Works
Pharmacodynamics: Lidocaine primarily acts by blocking voltage-gated sodium channels in nerve fibers, preventing depolarization and thus blocking nerve impulse transmission. Adrenaline constricts blood vessels at the injection site, leading to decreased systemic absorption of lidocaine, prolonged anesthetic duration, and reduced bleeding.
Pharmacokinetics: Lidocaine is rapidly absorbed after injection and metabolized primarily in the liver by CYP enzymes, with a small contribution from CYP3A4. Adrenaline is rapidly metabolized by COMT and MAO enzymes in the liver and other tissues. Both drugs and their metabolites are eliminated primarily via renal excretion.
Mechanism of Action: Lidocaine binds to the intracellular portion of voltage-gated sodium channels, stabilizing them in an inactive state. This prevents the influx of sodium ions required for nerve depolarization, effectively blocking nerve impulse propagation. Adrenaline acts on alpha- and beta-adrenergic receptors, causing vasoconstriction and various systemic effects like increased heart rate and blood pressure.
Elimination Pathways: Lidocaine is metabolized in the liver and excreted primarily through the kidneys. Adrenaline is metabolized by catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO) and excreted mainly via the kidneys as metabolites.
Dosage
Standard Dosage
Adults:
The dosage of lidocaine with adrenaline varies according to the procedure and patient. The maximum single dose of lidocaine with adrenaline is generally 500 mg. Commonly used doses for local infiltration range from 1% to 2% solutions, with a typical volume of 1-5 ml (20-100 mg lidocaine) per injection. Higher doses may be necessary for certain procedures but should not exceed the recommended maximum.
Children:
Dosing in children is weight-based and lower than adult doses. Consult a pediatric dosage guide for specific recommendations based on the child’s age and weight. For children over 3 years of age, consider 5 mg/kg/injection as a starting point.
Special Cases:
- Elderly Patients: Reduced doses are recommended due to age-related decrease in liver and kidney function.
- Patients with Renal Impairment: Dose adjustment may be required, although topical lidocaine demonstrates limited absorption.
- Patients with Hepatic Dysfunction: Dose reduction is advised as lidocaine is primarily metabolized in the liver.
- Patients with Comorbid Conditions: Caution is warranted in patients with cardiovascular disease, hypertension, hyperthyroidism, diabetes, epilepsy, respiratory dysfunction, and other relevant conditions.
Clinical Use Cases:
Dosing recommendations are highly variable and depend heavily on the specific clinical situation, patient condition, and anesthetic technique. Always consult relevant literature and guidelines.
Dosage Adjustments:
Dose modification is necessary based on patient-specific factors, including renal/hepatic dysfunction, age, and any concurrent medications. Close monitoring is essential, especially for continuous infusions or repeated injections.
Side Effects
Common Side Effects:
Reactions at the injection site (burning, itching, redness, swelling), nausea, vomiting.
Rare but Serious Side Effects:
Allergic reactions (anaphylaxis, angioedema), CNS toxicity (seizures, respiratory depression, loss of consciousness), cardiovascular effects (hypotension, bradycardia, arrhythmias).
Long-Term Effects:
Peripheral nerve damage (rare).
Adverse Drug Reactions (ADR):
Severe allergic reactions, seizures, cardiac arrhythmias.
Contraindications
Hypersensitivity to lidocaine or adrenaline, severe cardiovascular disease, certain arrhythmias, narrow-angle glaucoma, injection into areas with end arteries (fingers, toes).
Drug Interactions
Other local anesthetics, adrenaline-containing drugs, halothane, antiarrhythmics (e.g., amiodarone), beta-blockers (especially non-cardioselective), CYP3A4 inhibitors (e.g., cimetidine, erythromycin), tricyclic antidepressants, MAO inhibitors.
Pregnancy and Breastfeeding
Lidocaine crosses the placenta, and while generally considered safe for use during pregnancy, it should be used cautiously, especially during the first trimester. Adrenaline may reduce uterine blood flow. Both drugs are excreted in breast milk but at low concentrations and are generally considered safe for use during breastfeeding. It is unknown whether adrenaline enters breast milk.
Drug Profile Summary
- Mechanism of Action: Lidocaine blocks sodium channels, inhibiting nerve impulse transmission. Adrenaline causes vasoconstriction, prolonging the anesthetic effect.
- Side Effects: Common: Local reactions, nausea, vomiting. Serious: Allergic reactions, CNS toxicity, cardiovascular effects.
- Contraindications: Hypersensitivity, severe cardiovascular disease, narrow-angle glaucoma, injection into areas with end arteries.
- Drug Interactions: Other anesthetics, adrenaline-containing drugs, halothane, antiarrhythmics, beta-blockers, CYP3A4 inhibitors, tricyclic antidepressants, MAO inhibitors.
- Pregnancy & Breastfeeding: Generally safe, use with caution, especially in the first trimester. Excreted in breast milk at low concentrations.
- Dosage: Variable depending on procedure and patient; maximum single dose is generally 500 mg with adrenaline.
- Monitoring Parameters: Respiratory rate, heart rate, blood pressure, oxygen saturation, level of consciousness.
Popular Combinations
Lidocaine is often combined with adrenaline for local anesthesia. Adrenaline prolongs the anesthetic effect and reduces bleeding.
Precautions
Aspirate before injection to avoid intravascular administration. Monitor for signs of toxicity. Use caution in patients with pre-existing medical conditions. Advise patients to avoid driving or operating machinery if they experience drowsiness or dizziness.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Adrenaline + Lidocaine?
A: The dosage varies based on the procedure, patient factors, and concentration. The maximum single dose with adrenaline is usually 500 mg. Consult relevant guidelines.
Q2: What are the common side effects?
A: Common side effects include localized reactions (burning, itching, redness), nausea, and vomiting.
Q3: What are the serious side effects I should watch for?
A: Serious side effects include allergic reactions, CNS toxicity (seizures, respiratory depression), and cardiovascular effects (hypotension, bradycardia).
Q4: Can I use Lidocaine + Adrenaline during pregnancy?
A: While generally considered safe, use with caution, especially during the first trimester. Consult with an obstetrician.
Q5: Is it safe to breastfeed while using Lidocaine + Adrenaline?
A: It is generally considered safe, as both drugs are excreted in breast milk at low concentrations. It is unknown whether adrenaline enters breast milk.
Q6: What are the contraindications?
A: Contraindications include hypersensitivity, severe cardiovascular disease, narrow-angle glaucoma, and injection into areas with end arteries.
Q7: What are the major drug interactions?
A: Major drug interactions include those with other anesthetics, adrenaline-containing drugs, halothane, antiarrhythmics, and beta-blockers.
Q8: What precautions should I take when administering Lidocaine + Adrenaline?
A: Aspirate before injection, monitor vital signs, use cautiously in patients with comorbidities, and advise patients against activities requiring alertness if drowsiness or dizziness occur.
A: Lidocaine is metabolized primarily in the liver by CYP enzymes and eliminated via renal excretion. Adrenaline is metabolized by COMT and MAO enzymes and excreted via the kidneys as metabolites.
Q10: What is the mechanism by which Adrenaline prolongs Lidocaine’s anesthetic effects?
A: Adrenaline causes vasoconstriction at the injection site, reducing systemic absorption of lidocaine, resulting in a longer duration of action.
