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. |
| Molecular Weight | 234.34 |
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 | Lidocaine crosses the placenta and has not been associated with congenital malformations in humans, but due to potential for fetal bradycardia, use only if clearly needed. |
| 2nd trimester | Generally considered safe in the second trimester; monitor for maternal toxicity which could affect the fetus. Use lowest effective dose. |
| 3rd trimester | Use with caution; lidocaine may cause adverse effects on fetal heart rate and uterine tone. Avoid excessive doses and use only when necessary. |
Clinical note
Comprehensive clinical and safety monograph for XYLOCAINE PRESERVATIVE FREE (XYLOCAINE PRESERVATIVE FREE).
| Placental transfer | Lidocaine rapidly crosses the placenta via passive diffusion. Fetal concentrations are approximately 50% of maternal plasma levels. Higher transfer occurs with higher maternal doses or prolonged use. |
| Breastfeeding | Lidocaine is excreted into breast milk in small amounts (estimated 1-4% of maternal dose). It is unlikely to cause adverse effects in breastfeeding infants when used at recommended doses. However, caution is advised with continuous infusion or high doses. |
■ 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 |
Known hypersensitivity to lidocaine or amide-type local anestheticsHistory of severe adverse reaction to lidocaineSepticemia in lumbar puncture setting
| 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. |
| Food/Dietary | No known food interactions. |
Loading safety data…
| Lactation Rating | L2 |
| 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. |
| 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. |
| Clinical Pearls | 1. XYLOCAINE PRESERVATIVE FREE (lidocaine HCl) is an amide local anesthetic without preservatives (e.g., methylparaben), eliminating risk of allergic reactions in patients with paraben sensitivity. 2. Maximum recommended dose: 4.5 mg/kg (not exceeding 300 mg) for local infiltration; doses adjusted for pediatric, elderly, and debilitated patients. 3. Use with caution in patients with bradycardia, AV block, or severe hepatic disease due to reduced lidocaine clearance. 4. Always aspirate before injection to avoid intravascular administration, which can cause seizures or cardiac arrest. 5. Onset in 1–2 minutes for infiltration, duration 30–60 minutes with epinephrine prolonging to 2–6 hours. |
| Patient Advice | Temporary numbness or loss of sensation at the injection site is expected and may last several hours. · Avoid rubbing or scratching the numb area to prevent accidental injury. · Do not drive or operate machinery after administration until normal sensation returns. · Report any signs of allergic reaction: rash, itching, swelling, difficulty breathing. · Inform your doctor if you have liver disease, heart block, or epilepsy. · Keep out of reach of children. |