LIDOPEN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LIDOPEN (LIDOPEN).
Lidocaine is a sodium channel blocker, stabilizing neuronal membranes by inhibiting the influx of sodium ions, thereby preventing the propagation of action potentials and producing local anesthesia.
| Metabolism | Primarily metabolized in the liver by CYP1A2 and CYP3A4 to monoethylglycinexylidide (MEGX) and glycinexylidide (GX), which are pharmacologically active. |
| Excretion | Renal (10% unchanged; 80% as metabolites), biliary/fecal (10%) |
| Half-life | 1.5–2 hours (terminal); prolonged in hepatic impairment |
| Protein binding | 70–80% bound to alpha-1-acid glycoprotein (AAG) and albumin |
| Volume of Distribution | 0.7–1.5 L/kg; suggests extensive tissue distribution |
| Bioavailability | Oral: 35% (high first-pass metabolism); Intramuscular: 100% |
| Onset of Action | Intravenous: 30–60 seconds; Intramuscular: 5–15 minutes; Oral: 30–45 minutes |
| Duration of Action | Intravenous: 10–20 minutes; Intramuscular: 30–90 minutes; Oral: 1–2 hours |
Lidocaine 2% topical gel: Apply 1-2 grams (approximately 5-10 cm ribbon) to affected area every 4-6 hours as needed, not to exceed 5 grams per day. For infiltration anesthesia: 1% solution, 0.5-5 mL injected locally; maximum 4.5 mg/kg.
| Dosage form | INJECTABLE |
| Renal impairment | No specific dose adjustment required for topical or local administration. For systemic use: GFR 30-50 mL/min: reduce dose by 25%; GFR 10-29 mL/min: reduce dose by 50%; GFR <10 mL/min: avoid or use with caution due to metabolite accumulation. |
| Liver impairment | Child-Pugh Class A: no adjustment; Class B: reduce dose by 50%; Class C: avoid use or reduce dose by 75% and monitor for toxicity. |
| Pediatric use | Topical gel: Apply 0.5-1 g per 10-20 cm² area, not to exceed 3 mg/kg per application. Infiltration anesthesia: 0.5-1% solution, 1-2 mg/kg maximum dose; for neonatal: 0.5-1 mg/kg. |
| Geriatric use | Initiate at lower end of dosing range due to increased risk of systemic absorption and toxicity. Maximum topical dose: 3 g/day; local infiltration: use lowest effective volume and concentration. Monitor for CNS and cardiac effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for LIDOPEN (LIDOPEN).
| Breastfeeding | Lidocaine is excreted into breast milk in low concentrations, with a milk-to-plasma (M/P) ratio of approximately 0.4. The relative infant dose is estimated to be less than 10% of the maternal weight-adjusted dose, generally considered compatible with breastfeeding. However, monitor the infant for signs of lidocaine toxicity such as drowsiness, poor feeding, or respiratory depression. |
| Teratogenic Risk | LIDOPEN (lidocaine) is classified as FDA Pregnancy Category B. In the first trimester, no increased risk of major malformations has been observed in human studies, although animal studies have shown no fetal harm. During the second and third trimesters, lidocaine crosses the placenta and can cause fetal bradycardia, central nervous system depression, and acid-base disturbances, particularly with high doses or rapid intravenous administration. Use with caution, especially near term. |
■ FDA Black Box Warning
Risk of severe adverse reactions including cardiac arrest, respiratory depression, and seizures from accidental intravascular injection or systemic toxicity. Emergency resuscitative equipment must be immediately available.
| Serious Effects |
Hypersensitivity to lidocaine or amide anesthetics, severe heart block (without pacemaker), and untreated bacteremia (for spinal anesthesia).
| Precautions | Monitor for signs of CNS toxicity (dizziness, tinnitus, seizures) and cardiovascular toxicity (bradycardia, hypotension, arrhythmias). Use with caution in patients with hepatic impairment, heart block, or hypovolemia. |
| Food/Dietary | No clinically significant food interactions. However, avoid concurrent intake of oxidizing substances (e.g., nitrates) due to potential methemoglobinemia. |
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| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and ECG for arrhythmias or toxicity. In obstetrical use, monitor fetal heart rate continuously for signs of bradycardia or distress. Assess maternal neurological status for symptoms of lidocaine toxicity (e.g., perioral numbness, tinnitus, seizures). |
| Fertility Effects | Animal studies have not shown adverse effects on fertility. In humans, there are no known significant effects on male or female fertility from lidocaine use. However, any impact from underlying conditions or concurrent medications should be considered. |
| Clinical Pearls | Lidocaine/prilocaine (EMLA) requires at least 1 hour application for effective dermal analgesia; maximum application 4 hours. Do not apply to broken skin or mucous membranes except as directed. Risk of methemoglobinemia in infants <3 months or concurrent oxidizing agents. Use in labor analgesia: apply to perineum 15-20 minutes before delivery. For venipuncture, apply to dorsum of hand or antecubital fossa; occlude with dressing to enhance absorption. |
| Patient Advice | Apply thick layer to clean, dry skin and cover with plastic wrap for at least 1 hour before procedure. · Do not use on large areas of broken skin, eyes, or inside the mouth unless specifically instructed. · Remove cream after maximum 4 hours; prolonged use increases risk of side effects like numbness or tingling. · Avoid driving or operating machinery if numbness persists in hands/feet after procedure. · Inform doctor if you have breathing problems, glucose-6-phosphate dehydrogenase deficiency, or are taking medications like sulfonamides. |