XYLOCAINE W/ EPINEPHRINE
Clinical safety rating: safe
Beta-blockers may antagonize cardiac effects and cause severe hypertension Can cause angina and arrhythmias in patients with heart disease.
Lidocaine blocks voltage-gated sodium channels, inhibiting neuronal depolarization and conduction. Epinephrine causes vasoconstriction via alpha-1 adrenergic receptor agonism, reducing systemic absorption and prolonging local anesthetic action.
| Metabolism | Lidocaine is primarily metabolized in the liver via CYP1A2 and CYP3A4 to monoethylglycinexylidide (MEGX) and glycinexylidide (GX). Epinephrine is metabolized by monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). |
| Excretion | Renal: lidocaine and metabolites (primarily 4-hydroxyxylidine and glycinexylidide) ~90% as metabolites, <10% unchanged. Biliary/fecal: minor (approximately 3-5%). |
| Half-life | Lidocaine terminal half-life: ~1.5-2 hours (initial); ~2-4 hours (terminal) after IV. Prolonged in hepatic dysfunction (up to 5-7 hours) and congestive heart failure (up to 10 hours). |
| Protein binding | Lidocaine: 60-80% bound primarily to alpha-1-acid glycoprotein (AAG), with minor binding to albumin. Binding is saturable and concentration-dependent; increased in inflammatory states. |
| Volume of Distribution | Lidocaine Vd: 0.7-1.5 L/kg (average ~1.1 L/kg). Rapid distribution to highly perfused tissues (brain, heart, liver) followed by slower redistribution to adipose and muscle. Increased Vd in heart failure (up to 2 L/kg). |
| Bioavailability | IM: 100% (complete); Oral: approximately 35% (extensive first-pass metabolism); Topical: variable (<10% systemic absorption, concentration-dependent); Intranasal: approximately 50-80%; Rectal: approximately 50-60%. |
| Onset of Action | Subcutaneous infiltration: 2-5 minutes; Epidural: 5-15 minutes; Peripheral nerve block: 5-15 minutes; Topical: 2-5 minutes. |
| Duration of Action | Subcutaneous infiltration: 0.5-2 hours (with epinephrine: 2-6 hours); Epidural: 1-3 hours (with epinephrine: 2-4 hours); Peripheral nerve block: 1-3 hours (with epinephrine: 2-6 hours); Topical: 30-60 minutes. Epinephrine prolongs duration by vasoconstriction. |
| Molecular Weight | 234.34 |
Adults: 1-5 mL of 1% or 2% solution (maximum 7 mg/kg lidocaine without epinephrine; 7 mg/kg with epinephrine; not to exceed 500 mg total) by infiltration or nerve block, not to be repeated within 2 hours.
| Dosage form | INJECTABLE |
| Renal impairment | No specific GFR-based dose adjustment required; use with caution in severe renal impairment (GFR <15 mL/min) due to risk of accumulation of metabolites. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: contraindicated due to reduced clearance and increased risk of toxicity. |
| Pediatric use | Weight-based: 0.5-2 mg/kg lidocaine (max 4.5 mg/kg with epinephrine) via infiltration or nerve block; maximum dose per administration: 5 mg/kg with epinephrine, not to exceed 3 mg/kg on repeated doses. |
| Geriatric use | Elderly patients may require lower doses due to age-related decreased hepatic metabolism and increased risk of cardiovascular toxicity; start at lower end of dosing range (e.g., 1-3 mL of 1% solution) and titrate cautiously. |
| 1st trimester | Lidocaine crosses the placenta; use only if clearly needed. No known teratogenic effects in humans. |
| 2nd trimester | Lidocaine crosses the placenta; use only if clearly needed. No known teratogenic effects in humans. |
| 3rd trimester | Lidocaine crosses the placenta; use with caution near term due to potential fetal bradycardia or CNS depression. |
Clinical note
Beta-blockers may antagonize cardiac effects and cause severe hypertension Can cause angina and arrhythmias in patients with heart disease.
| FDA category | Animal |
| Placental transfer | Lidocaine rapidly crosses the placenta via passive diffusion; fetal/maternal ratio approximately 0.5-0.7. |
| Breastfeeding |
■ FDA Black Box Warning
Not for intravenous injection. Accidental IV administration can cause cardiac arrest, respiratory arrest, and death.
| Common Effects | cardiac arrest |
| Serious Effects |
Hypersensitivity to lidocaine, epinephrine, or amide-type anestheticsSevere hypertension or untreated hyperthyroidism (due to epinephrine)Concurrent use of MAO inhibitors or tricyclic antidepressants (risk of hypertensive crisis)Severe ventricular outflow obstruction (e.g., aortic stenosis) with epinephrine
| Precautions | Do not use in patients with hypersensitivity to amide anesthetics or epinephrine, Caution in patients with cardiovascular disease, hepatic impairment, or severe hypertension, Avoid intravascular injection; aspiration recommended before injection, Monitor for signs of systemic toxicity (CNS depression, cardiovascular collapse), May increase risk of methemoglobinemia in susceptible patients |
| Food/Dietary |
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| Lidocaine and epinephrine are excreted into breast milk in small amounts. The dose received by the infant is typically negligible. Observe infant for signs of local anesthetic toxicity. |
| Lactation Rating | L2 - Safer |
| Teratogenic Risk | Lidocaine: Not teratogenic in animal studies; use in pregnancy not associated with major congenital malformations. Epinephrine: Potential for reduced uterine blood flow if used in high doses or inadvertently intravascular. FDA Category B (lidocaine), Category C (epinephrine). |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and signs of systemic toxicity. Fetal heart rate monitoring recommended if large doses or inadvertent intravascular injection suspected. |
| Fertility Effects | No known adverse effects on fertility in humans. Lidocaine and epinephrine do not impair reproductive function in standard use. |
| No food interactions are known. Avoid alcohol consumption after injection as it may increase the risk of bleeding or vasodilation. |
| Clinical Pearls | Use with caution in vascular areas (fingers, toes, ears, nose) due to risk of ischemia from epinephrine-induced vasoconstriction. Limit epinephrine dose to 0.04 mg (40 mcg) per injection in these areas. Solutions with epinephrine are contraindicated in patients with thyrotoxicosis or severe hypertension. Always aspirate before injection to avoid intravascular administration. |
| Patient Advice | Temporary numbness and loss of sensation are expected and will resolve as the medication wears off. · Avoid eating or drinking until numbness has completely resolved to prevent accidental biting or burning. · Report any signs of allergic reaction such as rash, swelling, difficulty breathing, or rapid heart rate. · Inform your healthcare provider if you have high blood pressure, thyroid problems, or heart disease. |