LIDOCAINE HYDROCHLORIDE
Clinical safety rating: safe
Beta-blockers may increase the risk of lidocaine toxicity Can cause CNS toxicity (seizures) and cardiovascular collapse.
Lidocaine hydrochloride is a sodium channel blocker that inhibits voltage-gated sodium channels in neuronal and cardiac cell membranes, stabilizing the membrane and preventing depolarization, thereby blocking nerve impulses and exerting local anesthetic and antiarrhythmic effects.
| Metabolism | Lidocaine undergoes rapid hepatic metabolism primarily via cytochrome P450 enzymes, predominantly CYP3A4, and to a lesser extent CYP1A2. Major metabolites include monoethylglycinexylidide (MEGX) and glycinexylidide (GX), which are pharmacologically active. Less than 10% is excreted unchanged in the urine. |
| Excretion | Primarily hepatic metabolism (90% CYP3A4, also CYP1A2) to inactive metabolites (monoethylglycinexylidide, glycinexylidide); <10% excreted unchanged in urine. Renal elimination accounts for the majority of metabolite clearance. |
| Half-life | Terminal elimination half-life is 1.5–2 hours in adults. In patients with heart failure, hepatic cirrhosis, or those on CYP-inhibitors, half-life may be prolonged to ≥3 hours; in neonates, up to 3–6 hours. |
| Protein binding | 60–80% bound primarily to alpha-1-acid glycoprotein (AAG) and, to a lesser extent, albumin. Binding is saturable and increases in conditions with elevated AAG (e.g., inflammation, myocardial infarction). |
| Volume of Distribution | 1–1.5 L/kg in adults; higher in infants (2–3 L/kg). Distribution is rapid and extensive, reflecting high perfusion to well-perfused tissues (brain, heart, liver, kidneys). |
| Bioavailability | Oral: <35% (extensive first-pass metabolism) – not used orally for systemic effects. IM: 100% (complete absorption). Epidural: near 100%. Topical (intact skin): negligible (<1%); mucosal: 10–20% depending on site. |
| Onset of Action | IV: 45–90 seconds; IM: 5–15 minutes; Subcutaneous/local infiltration: <2 minutes; Epidural: 5–15 minutes; Topical (mucous membrane): 2–5 minutes. |
| Duration of Action | IV: 10–20 minutes (antiarrhythmic effect); IM: 30–90 minutes; Local infiltration: 0.5–1 hour (without epinephrine), 2–6 hours (with epinephrine); Epidural: 30–90 minutes; Topical: 15–45 minutes. |
IV: 1-1.5 mg/kg bolus, then 1-4 mg/min continuous infusion. Max: 3 mg/kg (300 mg) loading dose. For ventricular arrhythmias.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment recommended for GFR >10 mL/min. For GFR <10 mL/min, reduce maintenance infusion by 25-50% or use alternative agent due to risk of metabolite accumulation. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: avoid use or reduce dose by 75% with close monitoring. |
| Pediatric use | IV: Loading dose 1 mg/kg, may repeat once. Maintenance infusion: 20-50 mcg/kg/min. Max total dose: 3-5 mg/kg for infiltration anesthesia. |
| Geriatric use | Consider reduced initial bolus (0.5-1 mg/kg) and lower maintenance infusion rates (1-2 mg/min) due to decreased hepatic clearance and increased risk of toxicity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Beta-blockers may increase the risk of lidocaine toxicity Can cause CNS toxicity (seizures) and cardiovascular collapse.
| FDA category | Animal |
| Breastfeeding | Lidocaine is excreted into breast milk in small amounts (M/P ratio approximately 0.5-1.0). Typical maternal doses result in low infant exposure (less than 4% of the weight-adjusted maternal dose). Considered compatible with breastfeeding; monitor infant for signs of local anesthetic toxicity (irritability, drowsiness, poor feeding). |
| Teratogenic Risk |
■ FDA Black Box Warning
WARNING: LIFE-THREATENING AND FATAL ADVERSE EVENTS HAVE BEEN REPORTED WITH THE USE OF LIDOCAINE HYDROCHLORIDE, INCLUDING CARDIAC ARREST, SEIZURES, AND RESPIRATORY DEPRESSION. INTRAVASCULAR INJECTION OF LOCAL ANESTHETICS CAN CAUSE CARDIAC TOXICITY. RESUSCITATIVE EQUIPMENT AND MEDICATIONS FOR THE MANAGEMENT OF TOXIC REACTIONS MUST BE IMMEDIATELY AVAILABLE.
| Common Effects | ventricular arrhythmias |
| Serious Effects |
["Hypersensitivity to lidocaine, amide-type anesthetics, or any component of the formulation.","Severe shock or severe preexisting heart block (without pacemaker).","Adams-Stokes syndrome.","Wolff-Parkinson-White syndrome (for antiarrhythmic use).","Intra-articular injection in patients with joint infection or significant joint pathology."]
| Precautions | ["May cause cardiac toxicity, including bradycardia, hypotension, and cardiac arrest, especially with high doses or rapid IV administration.","Central nervous system toxicity can lead to seizures, confusion, and respiratory depression.","Use with caution in patients with hepatic impairment (reduced clearance), severe renal disease, or heart failure.","Risk of methemoglobinemia with high doses or concurrent use of oxidizing agents.","Not recommended for routine use in pregnancy; only if benefit outweighs risk to fetus.","May cause local irritation or allergic reactions; discontinue if signs of hypersensitivity occur."] |
Loading safety data…
| FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. Lidocaine crosses the placenta; fetal plasma concentrations are approximately 50-60% of maternal levels. No increased risk of major congenital anomalies reported with standard doses. Second and third trimester: use with caution due to potential fetal bradycardia and acidosis, especially with high doses or repeated administration. First trimester: low risk, but avoid unnecessary use. |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and ECG for arrhythmias or toxicity (CNS depression, seizures). Monitor fetal heart rate for bradycardia, especially with higher doses or repeated administration. Assess for signs of fetal acidosis if prolonged use. Observe neonate for respiratory depression if used near delivery. |
| Fertility Effects | No known adverse effects on fertility in humans. Animal studies show no impairment of fertility at subtoxic doses. Lidocaine is not associated with altered sperm parameters or ovulation. |