XYLOCAINE PRESERVATIVE FREE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for XYLOCAINE PRESERVATIVE FREE (XYLOCAINE PRESERVATIVE FREE).
Lidocaine stabilizes the neuronal membrane by inhibiting sodium ion influx, thereby blocking impulse initiation and conduction. It binds to voltage-gated sodium channels in the inactivated state, preventing depolarization and propagation of action potentials.
| Metabolism | Primarily hepatic via CYP1A2 (major) and CYP3A4 (minor) to monoethylglycinexylidide (MEGX) and glycinexylidide (GX), which are less active. Further hydrolysis and conjugation produce metabolites excreted renally. |
| Excretion | Renal excretion of metabolites (90-95% as metabolites, <5% unchanged); biliary/fecal excretion minimal (<1%). |
| Half-life | Terminal elimination half-life approximately 1.5-2 hours in adults; prolonged in hepatic impairment (up to 3-4 hours) and congestive heart failure. |
| Protein binding | 65-75% primarily to alpha-1-acid glycoprotein (AAG) and albumin; binding is concentration-dependent and saturable. |
| Volume of Distribution | 1.0-1.7 L/kg; rapid distribution into highly perfused organs (brain, heart, lungs) followed by redistribution to skeletal muscle and adipose tissue. |
| Bioavailability | Oral: <20% (extensive first-pass metabolism); epidural: nearly 100%; topical: minimal systemic absorption (depends on site and condition of skin). |
| Onset of Action | IV: <1 minute; epidural: 5-15 minutes; peripheral nerve block: 4-17 minutes; topical: 2-5 minutes. |
| Duration of Action | IV: 10-20 minutes; epidural: 30-90 minutes (with epinephrine: 60-180 minutes); peripheral nerve block: 60-200 minutes; topical: 30-60 minutes. |
Adult dose: 1-30 mL of 1% or 2% solution (10-600 mg) via subcutaneous infiltration, peripheral nerve block, or epidural; max 4.5 mg/kg (300 mg without epinephrine, 7 mg/kg [500 mg] with epinephrine) per 2-hour period.
| Dosage form | INJECTABLE |
| Renal impairment | No specific GFR-based dose adjustment required; lidocaine pharmacokinetics minimally affected by renal impairment. |
| Liver impairment | Child-Pugh Class A: No adjustment. Class B: Reduce dose by 50% and monitor. Class C: Contraindicated or use minimal dose with extreme caution due to reduced metabolism. |
| Pediatric use | Infiltration: 0.25-0.5% solution, max 4.5 mg/kg. Nerve block: 0.5-1.5% solution, max 4.5 mg/kg. Epidural: 1-2% solution, 1-2 mg/kg. Repeat no sooner than 2 hours. |
| Geriatric use | Reduce initial dose by 20-40% (e.g., max 3 mg/kg plain) due to decreased clearance; titrate to effect; monitor for CNS and cardiac toxicity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for XYLOCAINE PRESERVATIVE FREE (XYLOCAINE PRESERVATIVE FREE).
| Breastfeeding | Lidocaine is excreted into breast milk in small amounts; M/P ratio approximately 0.4. Infant dose is less than 5% of maternal weight-adjusted dose. Compatible with breastfeeding with caution; observe infant for drowsiness. |
| Teratogenic Risk | Lidocaine crosses the placenta. First trimester: no increased risk of major malformations reported in human studies. Second and third trimesters: can cause fetal bradycardia and central nervous system depression if high maternal serum levels occur; use lowest effective dose. |
■ FDA Black Box Warning
None for Xylocaine Preservative Free (lidocaine HCl injection). However, lidocaine with epinephrine carries a boxed warning regarding potential for cardiovascular toxicity and inadvertent intravascular injection.
| Serious Effects |
Hypersensitivity to lidocaine, amide-type anesthetics, or any component of the formulation; patients with Stokes-Adams syndrome, Wolff-Parkinson-White syndrome, or severe degrees of sinoatrial, atrioventricular, or intraventricular block without a pacemaker; concomitant use with class I antiarrhythmic drugs (e.g., mexiletine, tocainide).
| Precautions | Risk of dose-related CNS and cardiovascular toxicity; monitor for signs of toxicity. Use with caution in patients with hepatic impairment, heart failure, bradycardia, or severe hypovolemia. Avoid intravascular injection; aspiration before injection recommended. May cause methemoglobinemia, especially with concurrent use of oxidizing agents. |
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| Fetal Monitoring |
| Monitor maternal vital signs (heart rate, blood pressure), ECG for arrhythmias or toxicity; fetal heart rate monitoring during prolonged use; assess for signs of local anesthetic systemic toxicity (LAST). |
| Fertility Effects | No evidence of impaired fertility in animal studies; no human data on reproductive function. |