LIDOCAINE HYDROCHLORIDE W/ EPINEPHRINE
Clinical safety rating: safe
Beta-blockers may increase the risk of lidocaine toxicity Can cause CNS toxicity (seizures) and cardiovascular collapse.
Lidocaine is a sodium channel blocker that inhibits voltage-gated sodium channels, preventing depolarization and conduction of nerve impulses. Epinephrine is an alpha- and beta-adrenergic agonist that causes vasoconstriction, reducing systemic absorption of lidocaine and prolonging local anesthetic effect.
| Metabolism | Lidocaine: primarily hepatic via CYP1A2 and CYP3A4; major metabolite monoethylglycinexylidide (MEGX) and glycinexylidide (GX). Epinephrine: metabolized by catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). |
| Excretion | Renal: unchanged drug <10%, major metabolites (MEGX and GX) ~70% renal; biliary: <10% fecal; total clearance ~10-20 mL/min/kg. Renal impairment prolongs elimination of metabolites. |
| Half-life | Terminal half-life 1.5-2 hours (single dose), prolonged to 2-3 hours with continuous infusion; in heart failure or hepatic cirrhosis, half-life may exceed 5 hours. |
| Protein binding | ~65-75% bound primarily to alpha-1-acid glycoprotein (AAG); binding is concentration-dependent and increases with AAG levels (e.g., inflammation, stress). |
| Volume of Distribution | Vd ~1.0-1.5 L/kg; decreased in heart failure (0.5-0.8 L/kg) and increased in hepatic disease (up to 2.0 L/kg). |
| Bioavailability | IM: 100% (intravascular absorption); oral: <15% due to extensive first-pass hepatic metabolism; epidural: ~100% (systemic absorption). |
| Onset of Action | IV: 45-90 seconds; IM: 10-15 minutes; epidural: 5-15 minutes; subcutaneous infiltration: immediate. |
| Duration of Action | IV: 10-20 minutes (single dose); IM: 60-90 minutes; epidural: 60-120 minutes; with epinephrine, duration extended by ~50% due to vasoconstriction. |
| Molecular Weight | 234.34 |
Local anesthesia: 1-5 mL of 1% or 2% solution with epinephrine 1:100,000 or 1:200,000; maximum dose 7 mg/kg lidocaine (500 mg without epinephrine, 7 mg/kg with epinephrine) per procedure. Intravenous: 1-1.5 mg/kg bolus for ventricular arrhythmias, followed by continuous infusion 1-4 mg/min.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for lidocaine; however, active metabolite MEGX may accumulate in severe renal impairment (GFR <15 mL/min), consider monitoring for toxicity. No specific GFR-based dose modifications. |
| Liver impairment | Child-Pugh Class A: No adjustment. Child-Pugh Class B: Reduce dose by 50% or prolong dosing interval. Child-Pugh Class C: Reduce dose by 50-75% or use alternative. Lidocaine clearance is significantly decreased in severe hepatic impairment. |
| Pediatric use | Local anesthesia: Max 4.5 mg/kg lidocaine with epinephrine (1:100,000), not to exceed single dose. Intravenous for arrhythmias: Loading dose 1 mg/kg, repeat 0.5-1 mg/kg if needed, then continuous infusion 20-50 mcg/kg/min. |
| Geriatric use | Lower initial doses recommended due to reduced hepatic blood flow and clearance. For local anesthesia, use lowest effective dose. For intravenous, start with lower end of dosing range (e.g., 0.5-1 mg/kg bolus) and monitor for toxicity. |
| 1st trimester | Lidocaine with epinephrine is generally considered safe during the first trimester when used in minimal effective doses. However, caution is advised as high doses or prolonged use may be associated with fetal bradycardia or other adverse effects. |
| 2nd trimester | Similar to T1, use with caution. Epinephrine may reduce uterine blood flow, but low doses used for local anesthesia are typically considered low risk. |
| 3rd trimester | Use with caution, especially near term, as epinephrine can cause uterine vasoconstriction and reduce placental perfusion. Lidocaine itself crosses placenta but is generally safe in clinical doses. |
Clinical note
Beta-blockers may increase the risk of lidocaine toxicity Can cause CNS toxicity (seizures) and cardiovascular collapse.
| FDA category | Animal |
| Placental transfer | Lidocaine crosses the placenta by passive diffusion. The fetal: maternal ratio is approximately 0.5-0.7. Epinephrine has limited placental transfer due to rapid metabolism. |
■ FDA Black Box Warning
Not for use in obstetrical paracervical block (severe fetal bradycardia and death). Do not inject into infected or inflamed tissues. Intravenous administration of lidocaine/epinephrine may cause severe hypertension, stroke, or death due to epinephrine.
| Common Effects | ventricular arrhythmias |
| Serious Effects |
Known hypersensitivity to local anesthetics of the amide type or to epinephrineSevere hypotensionSulfite allergy (if product contains sulfites)Intravenous regional anesthesia (Bier block)Severe hepatic impairment (relative but often absolute for large doses)
| Precautions | Risk of systemic toxicity (CNS and cardiovascular) from accidental intravascular injection; use lowest effective dose. Caution in patients with hepatic impairment, heart block, severe bradycardia, hypotension, hypovolemia, and with concomitant use of CYP1A2 or CYP3A4 inhibitors. Epinephrine may cause hypertension, tachycardia, and arrhythmias; avoid in patients with severe hypertension, hyperthyroidism, or pheochromocytoma. |
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| Breastfeeding | Lidocaine and epinephrine are excreted into breast milk in small amounts. Oral bioavailability is low, so systemic effects in the infant are unlikely. Use caution with high doses or repeated use. The American Academy of Pediatrics considers lidocaine compatible with breastfeeding. |
| Lactation Rating | L2 (Limited data - probably compatible) |
| Teratogenic Risk | FDA Pregnancy Category B. Lidocaine crosses placenta. No confirmed teratogenicity in human studies; epinephrine may reduce uteroplacental blood flow at high doses. First trimester: low risk; second/third trimester: neutral; peripartum: possible fetal bradycardia or acidosis at high doses. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, ECG, and signs of local anesthetic systemic toxicity (LAST). Fetal heart rate monitoring recommended during prolonged or high-dose administration. Assess for uterine hypertonus if epinephrine contraindicated. |
| Fertility Effects | No known adverse effects on fertility in humans. Animal studies show no impairment at clinically relevant doses. Epinephrine may affect uterine blood flow transiently; no evidence of long-term fertility impact. |
| Food/Dietary | No specific food interactions. Avoid excessive caffeine intake as it may enhance epinephrine side effects (tachycardia, anxiety). |
| Clinical Pearls | 1. Limit total lidocaine dose to 7 mg/kg (with epinephrine) to avoid CNS and cardiac toxicity. 2. Use lower doses in elderly, hepatic impairment, or heart failure. 3. Avoid in patients with severe hypertension or hyperthyroidism due to epinephrine. 4. Do not inject intravenously; aspirate before injection to avoid intravascular administration. 5. Monitor for signs of systemic toxicity: perioral numbness, metallic taste, tinnitus, seizures, arrhythmias. |
| Patient Advice | You may experience temporary numbness or tingling at the injection site. · Do not drive or operate machinery until numbness resolves and effects of epinephrine wear off. · Seek emergency care if you experience rapid heart rate, difficulty breathing, or severe headache. · Report any signs of infection like redness, swelling, or pus at the injection site. · Avoid rubbing or massaging the injection area to prevent spreading the medication. |