XYLOCAINE DENTAL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for XYLOCAINE DENTAL (XYLOCAINE DENTAL).
Lidocaine is an amide-type local anesthetic that stabilizes the neuronal membrane by inhibiting sodium ion influx, thereby blocking the initiation and conduction of nerve impulses.
| Metabolism | Primarily hepatic via CYP1A2 and CYP3A4; major metabolite is monoethylglycinexylidide (MEGX), followed by glycinexylidide (GX). |
| Excretion | Renal excretion of unchanged drug and metabolites accounts for >95% of the dose. Approximately 70% is excreted as the metabolite 4-hydroxy-2,6-xylidine; less than 10% is unchanged lidocaine. Biliary/fecal excretion is minimal (<5%). |
| Half-life | 1.5–2 hours in adults with normal hepatic function. Prolonged to 2–3 hours in patients with hepatic impairment or congestive heart failure; may exceed 5 hours in severe hepatic disease. |
| Protein binding | Approximately 60–80% bound to alpha-1-acid glycoprotein (AAG). Binding is concentration-dependent and saturable. |
| Volume of Distribution | 1.1–1.7 L/kg in adults. Higher Vd (>2 L/kg) in patients with cardiac failure or hepatic disease due to reduced clearance. |
| Bioavailability | Oral bioavailability is approximately 35% due to extensive first-pass hepatic metabolism. Not administered orally clinically; intravenous bioavailability is 100%. |
| Onset of Action | Infiltration: 2–5 minutes. Nerve block: 5–10 minutes. Onset is faster with epinephrine-containing formulations due to vasoconstriction. |
| Duration of Action | Infiltration without epinephrine: 30–60 minutes. With epinephrine (1:100,000): 60–120 minutes for soft tissue anesthesia; 90–180 minutes for pulpal anesthesia. Duration is shorter in highly vascular areas. |
| Molecular Weight | 234.34 |
Xylocaine Dental (lidocaine HCl 2% with epinephrine 1:100,000 or 1:50,000): For infiltration/inferior alveolar nerve block, maximum dose 3.4 mg/kg (4.5 mg/kg with epinephrine 1:100,000) not to exceed 300 mg; usual adult dose: 1–5 mL (20–100 mg) administered via oral submucosal injection.
| Dosage form | INJECTABLE |
| Renal impairment | No adjustment required for standard dosing; however, caution in severe renal impairment (eGFR <30 mL/min) due to potential accumulation of metabolites (MEGX, GX); use reduced doses and monitor for toxicity. |
| Liver impairment | In Child-Pugh class B or C, reduce dose by 50% due to decreased clearance; avoid in severe hepatic impairment unless benefits outweigh risks; monitor for signs of CNS toxicity. |
| Pediatric use | Weight-based dosing: maximum 4.5 mg/kg with epinephrine 1:100,000 (absolute max 300 mg). Example: For 20 kg child, max dose = 90 mg (4.5 mL of 2% solution). Dose volume adjusted to achieve adequate anesthesia. |
| Geriatric use | Elderly patients may have reduced hepatic clearance; use lowest effective dose and limit total dose to 200 mg (10 mL of 2% solution) with epinephrine; monitor for prolonged effect and cardiovascular changes. |
| 1st trimester | Lidocaine is not teratogenic in animal studies; however, use only if clearly needed. Avoid use during first trimester if possible due to theoretical risk of fetal bradycardia. |
| 2nd trimester | Use with caution; monitor fetal heart rate if used in large doses. Lidocaine is generally considered safe in dental procedures. |
| 3rd trimester | Avoid use near term or during labor due to risk of fetal bradycardia and neonatal CNS depression. Use only if benefits outweigh risks. |
Clinical note
Comprehensive clinical and safety monograph for XYLOCAINE DENTAL (XYLOCAINE DENTAL).
| Placental transfer | Lidocaine readily crosses the placenta with fetal/maternal ratio of approximately 0.5-0.7. Equilibrium is reached within 30-60 minutes after maternal administration. |
| Breastfeeding | Lidocaine is excreted into breast milk in small amounts, unlikely to cause adverse effects in infants. However, monitor infant for signs of toxicity (e.g., drowsiness, poor feeding) if high doses are used. The American Academy of Pediatrics considers lidocaine compatible with breastfeeding. |
■ FDA Black Box Warning
Not applicable (no FDA black box warning for Xylocaine Dental).
| Serious Effects |
Hypersensitivity to lidocaine or any amide local anestheticSevere sinoatrial, atrioventricular, or intraventricular block without pacemakerMyasthenia gravis (use with caution; may exacerbate weakness)
| Precautions | Risk of systemic toxicity if injected intravascularly or overdosed, Use with caution in patients with hepatic impairment, severe renal impairment, or cardiac disease, Avoid use in patients with myasthenia gravis or pseudocholinesterase deficiency, Methemoglobinemia risk with high doses or concurrent use of oxidizing agents |
| Food/Dietary | No specific food interactions. Avoid consuming hot foods/beverages until anesthesia resolves to prevent oral mucosal burns. Do not eat or drink until sensation returns to prevent inadvertent injury. |
Loading safety data…
| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | Lidocaine (Xylocaine) crosses the placenta. First trimester: No evidence of major malformations from human data, but risk cannot be excluded. Second/third trimesters: Use as dental anesthetic is considered low risk; no increased teratogenicity reported. Continuous infusion or high doses may cause fetal bradycardia or acidosis. |
| Fetal Monitoring | Standard maternal vital signs; fetal heart rate monitoring if used peripartum or with large doses. No specific fetal surveillance required for routine dental anesthesia. |
| Fertility Effects | No evidence of impaired fertility in animal studies or human reports. |
| Clinical Pearls | Xylocaine Dental (lidocaine) is an amide local anesthetic. For maxillary infiltration, use 1.8 mL per site; for mandibular block, 3.6 mL. Onset 2-5 min, duration 60-120 min. Do not exceed 4.5 mg/kg (with epinephrine) or 7 mg/kg max dose. Avoid in patients with severe liver disease or hypersensitivity to amide anesthetics. Inadvertent intravascular injection can cause seizures or cardiac arrest; always aspirate before injection. Use with caution in patients on class III antiarrhythmics (e.g., amiodarone) due to additive cardiotoxicity. |
| Patient Advice | Do not eat or drink until normal sensation returns after dental procedure to prevent biting your tongue or cheek. · The numbness will last 1-2 hours; avoid hot foods or beverages to prevent burns. · Report any signs of allergic reaction: rash, swelling, difficulty breathing. · Inform your dentist if you have liver disease, heart problems, or are taking heart rhythm medications. · Do not drive or operate machinery if you feel dizzy or lightheaded after the injection. |