LIDOCAINE VISCOUS
Clinical safety rating: safe
Beta-blockers may increase the risk of lidocaine toxicity Can cause CNS toxicity (seizures) and cardiovascular collapse.
Lidocaine is an amide-type local anesthetic that blocks voltage-gated sodium channels (Nav1.7, Nav1.8) in neuronal membranes, inhibiting depolarization and propagation of action potentials, thereby producing local anesthesia. It also has antiarrhythmic properties (class IB) by blocking sodium channels in cardiac myocytes.
| Metabolism | Hepatic metabolism primarily via CYP1A2 and CYP3A4 to monoethylglycinexylidide (MEGX) and glycinexylidide (GX); 90% undergoes dealkylation; less than 10% excreted unchanged in urine. |
| Excretion | Renal excretion of unchanged drug and metabolites accounts for >90% of elimination; <10% biliary/fecal. Metabolites include monoethylglycinexylidide (MEGX) and glycinexylidide (GX). |
| Half-life | Terminal elimination half-life is 1.5–2 hours (up to 3 hours in hepatic impairment). Clinically, redistribution half-life (~6 min) determines duration of action after short infusions. |
| Protein binding | 70–80% bound to alpha-1-acid glycoprotein (AAG) and albumin. Binding saturable and variable in disease states. |
| Volume of Distribution | Vd ~0.7–1.5 L/kg. Rapid distribution to highly perfused tissues (brain, heart), followed by slower equilibration with muscle and fat. |
| Bioavailability | Oral/topical: ~35% (due to extensive first-pass hepatic metabolism). Rectal: higher but variable (up to 50%). |
| Onset of Action | Oral/topical: 1–5 minutes for local anesthesia. |
| Duration of Action | 30–60 minutes for topical anesthesia. Prolonged in inflamed tissue or with co-administered vasoconstrictors. Systemic toxicity may persist longer. |
| Molecular Weight | 234.34 |
15 mL (300 mg) orally every 3 hours as needed for pain; maximum 8 doses per 24 hours.
| Dosage form | SOLUTION |
| Renal impairment | eGFR ≥15 mL/min: No adjustment. eGFR <15 mL/min: Use with caution; reduce dose or increase interval; avoid prolonged use. |
| Liver impairment | Child-Pugh A or B: Reduce total daily dose by 50%. Child-Pugh C: Contraindicated due to risk of systemic toxicity. |
| Pediatric use | Weight-based: 1-2 mg/kg per dose (max 4.5 mg/kg total per day) orally, applied topically to oral mucosa; not for systemic use in neonates. |
| Geriatric use | Initiate at low end of adult dosing (e.g., 15 mL every 6-8 hours), monitor for CNS side effects and arrhythmias; consider reduced clearance. |
| 1st trimester | Avoid unless clearly needed; fetal bradycardia risk and potential central nervous system depression. |
| 2nd trimester | Use with caution; minimal systemic absorption if applied topically but risk of maternal toxicity with excessive use. |
| 3rd trimester | Use with caution; potential for fetal bradycardia and neonatal CNS depression if high doses absorbed. |
Clinical note
Beta-blockers may increase the risk of lidocaine toxicity Can cause CNS toxicity (seizures) and cardiovascular collapse.
| FDA category | Animal |
| Placental transfer | Rapidly crosses placenta; fetal levels can be ~50-80% of maternal levels after IV administration; lower with topical use. |
| Breastfeeding |
■ FDA Black Box Warning
Not available (no FDA boxed warning for lidocaine viscous). However, lidocaine solutions >2% or inappropriately high doses can cause systemic toxicity, including cardiac arrest and death.
| Common Effects | ventricular arrhythmias |
| Serious Effects |
Hypersensitivity to lidocaine or amide-type anestheticsStokes-Adams syndromeWolff-Parkinson-White syndrome
| Precautions | Do not exceed recommended dose; excessive dosing can lead to systemic toxicity, including CNS excitation/depression and cardiac arrhythmias., Use with caution in patients with hepatic impairment, congestive heart failure, or severe bradycardia., Avoid use in patients with septicemia or severe trauma to mucosa., May cause methemoglobinemia when used with other oxidizing agents (e.g., benzocaine). |
| Food/Dietary |
Loading safety data…
| Minimal excretion into breast milk; use lowest effective dose for shortest duration; monitor infant for sedation or irritability. |
| Lactation Rating | L2 (Probably Compatible) or 'Safe' |
| Teratogenic Risk | Lidocaine crosses the placenta. First trimester: No well-documented teratogenicity in humans; animal studies show no fetal harm at clinically relevant doses. Second/third trimester: Risk of fetal bradycardia, central nervous system depression, and acidosis with high maternal doses or inadvertent intravascular administration. Avoid paracervical block for obstetric anesthesia due to potential fetal acidosis. |
| Fetal Monitoring | Maternal: Monitor for signs of systemic toxicity (perioral numbness, tinnitus, metallic taste, seizures, arrhythmias). Fetal: Continuous fetal heart rate monitoring during labor if used for analgesia; assess fetal heart rate variability for bradycardia. |
| Fertility Effects | No known adverse effects on fertility in humans. Animal studies show no impairment of fertility at clinical doses. |
| Avoid eating or drinking until oral sensation returns (usually 30-60 minutes after use) to prevent choking or biting injury. No known drug-food interactions. |
| Clinical Pearls | Lidocaine viscous 2% is primarily used for topical anesthesia of the oropharyngeal mucosa. Onset is within 1-2 minutes and duration lasts 30-60 minutes. Maximum recommended dose is 4.5 mg/kg (300 mg for adults) to avoid systemic toxicity. Use with caution in patients with hepatic impairment, heart block, or those receiving Class I antiarrhythmics. Do not apply to broken skin or open wounds to avoid rapid absorption. |
| Patient Advice | Use only as directed; do not exceed the prescribed dose or frequency. · Swish the solution in your mouth for 15 seconds then spit it out; do not swallow. · Numbness of the tongue or mouth is expected; avoid chewing gum or eating until sensation returns to prevent injury. · Do not use for more than 5 days unless instructed by your doctor. · Seek immediate medical attention if you experience dizziness, blurred vision, seizures, or difficulty breathing. · Keep out of reach of children; accidental ingestion can cause serious side effects. · Store at room temperature away from moisture and heat. |