LIDOSITE TOPICAL SYSTEM KIT
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LIDOSITE TOPICAL SYSTEM KIT (LIDOSITE TOPICAL SYSTEM KIT).
Lidocaine is an amide-type local anesthetic that stabilizes neuronal membranes by blocking voltage-gated sodium channels, thereby inhibiting the initiation and conduction of nerve impulses.
| Metabolism | Lidocaine is primarily metabolized in the liver via oxidative N-dealkylation by CYP1A2 and CYP3A4 to monoethylglycinexylidide (MEGX) and glycinexylidide (GX), both active metabolites. Further metabolism involves hydrolysis and conjugation. |
| Excretion | Renal (80-90% as metabolites, <10% unchanged), biliary/fecal (minor, <5%) |
| Half-life | 1.5-2 hours (terminal); prolonged in hepatic dysfunction or heart failure |
| Protein binding | 65-75% (primarily to alpha-1-acid glycoprotein and albumin) |
| Volume of Distribution | 1.1-1.6 L/kg (extensive tissue distribution, e.g., brain, heart, liver) |
| Bioavailability | Topical: variable, ~3-10% systemically absorbed depending on site and condition; systemic routes not applicable |
| Onset of Action | Topical: 3-5 minutes for local anesthesia |
| Duration of Action | Topical: 30-60 minutes; prolonged with epinephrine or in inflamed tissue |
| Molecular Weight | 234.34 |
Apply up to 3 patches topically once daily for up to 12 hours per day. Maximum 3 patches (210 mg lidocaine) per day.
| Dosage form | PATCH |
| Renal impairment | No dose adjustment required for GFR ≥30 mL/min. For GFR <30 mL/min, use with caution and monitor for lidocaine toxicity due to reduced clearance. |
| Liver impairment | Child-Pugh A: No adjustment. Child-Pugh B: Reduce dose (e.g., apply 1-2 patches, maximum 12 hours). Child-Pugh C: Contraindicated or use with extreme caution, consider alternative therapy. |
| Pediatric use | Not recommended for use in pediatric patients (safety and efficacy not established). For off-label use in children ≥2 years, apply 1 patch (5% lidocaine) for 12 hours, maximum 3 patches. Weight-based not applicable. |
| Geriatric use | No specific dose adjustment required but monitor for adverse effects due to age-related changes in skin integrity and renal function. Use lowest effective number of patches and limit to 12-hour application. |
| 1st trimester | Topical lidocaine is generally avoided in the first trimester unless clearly needed. Limited data; systemic absorption is minimal but risks are unknown. Use only if potential benefit justifies risk. |
| 2nd trimester | Topical lidocaine may be used if clearly indicated. Sparse data but systemic absorption is low. No known teratogenic effects in animal studies. |
| 3rd trimester | Topical lidocaine is considered safe in the third trimester. Low systemic absorption. However, avoid excessive use or application to broken skin. No known fetal harm. |
Clinical note
Comprehensive clinical and safety monograph for LIDOSITE TOPICAL SYSTEM KIT (LIDOSITE TOPICAL SYSTEM KIT).
| Placental transfer | Minimal placental transfer due to low systemic absorption after topical application. Lidocaine crosses the placenta after IV or epidural administration, but topical use results in negligible maternal plasma levels. |
| Breastfeeding |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to lidocaine or any componentSevere hepatic impairment (due to risk of toxicity from absorbed lidocaine)Application to large areas of broken or inflamed skin (increased systemic absorption)Concurrent use with Class I antiarrhythmics (e.g., tocainide, mexiletine) due to additive toxicity
| Precautions | May cause methemoglobinemia, especially in patients with glucose-6-phosphate dehydrogenase deficiency, anemia, or those taking oxidizing agents., Use with caution in patients with severe hepatic impairment or impaired cardiovascular function., Do not apply to open wounds, broken skin, or mucous membranes., Avoid contact with eyes., Potential for systemic toxicity if applied to large areas, over prolonged periods, or with compromised circulation. |
| Food/Dietary | No known food interactions with topical lidocaine/tetracaine. |
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| Topical lidocaine is minimally absorbed systemically; breastfeeding is considered safe. However, avoid application to the breast or nipple area to prevent infant ingestion. Monitor for infant irritability or sedation if used extensively. |
| Lactation Rating | L2 (Safe; probably compatible) |
| Teratogenic Risk | Lidocaine crosses the placenta. First trimester: Limited human data, no increased risk of major malformations in epidemiologic studies. Second and third trimesters: Use may cause fetal bradycardia, central nervous system depression, or acidosis if high maternal serum levels occur. Avoid use during active labor due to potential neonatal respiratory depression. |
| Fetal Monitoring | Monitor maternal heart rate, blood pressure, and respiratory status. Assess for signs of systemic toxicity (perioral numbness, metallic taste, dizziness, seizures). Fetal monitoring: If used during labor, continuous fetal heart rate monitoring for bradycardia or non-reassuring patterns. |
| Fertility Effects | No known adverse effects on fertility in humans. Lidocaine does not interfere with spermatogenesis or oocyte maturation. |
| Clinical Pearls | Lidosite Topical System Kit combines lidocaine and tetracaine for dermal anesthesia. Apply to intact skin; avoid broken skin. Max application area: 400 cm². Remove after 4 hours to prevent systemic toxicity. Monitor for methemoglobinemia in patients with G6PD deficiency, those on sulfonamides, or infants. Do not apply near eyes or mucous membranes. |
| Patient Advice | Apply only to intact, clean, dry skin. · Cover the area with the included dressing; do not occlude for more than 4 hours. · Do not apply to large areas (max 400 cm²) or for longer than recommended. · Avoid heat sources (e.g., heating pads, sunbathing) over the application site. · Seek immediate medical attention if you experience dizziness, difficulty breathing, or bluish skin. · Keep out of reach of children. |