Comparative Pharmacology
Head-to-head clinical analysis: EMLA versus NESACAINE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: EMLA versus NESACAINE.
EMLA vs NESACAINE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
EMLA is a eutectic mixture of lidocaine 2.5% and prilocaine 2.5%. Lidocaine and prilocaine are amide-type local anesthetics that block sodium ion channels in neuronal membranes, inhibiting the initiation and conduction of nerve impulses, thereby producing local analgesia.
Nesacaine (chloroprocaine) is an ester-type local anesthetic that blocks voltage-gated sodium channels in neuronal membranes, inhibiting the initiation and conduction of nerve impulses.
Apply a thick layer of cream (approximately 2.5 g per 20 cm²) to intact skin under an occlusive dressing for at least 1 hour for minor procedures; for dermal procedures on larger areas, apply up to 60 minutes before procedure, maximum single application area of 600 cm² in adults.
Injectable local anesthetic: 1% or 2% solution, maximum dose 7 mg/kg (not to exceed 500 mg) with epinephrine, 4.5 mg/kg (not to exceed 300 mg) without epinephrine. Administer by infiltration or nerve block; may repeat at 30-minute intervals.
None Documented
None Documented
After topical application, the terminal elimination half-life of lidocaine is approximately 1.5-2 hours; prilocaine half-life is approximately 1.5 hours. In neonates, half-life may be prolonged due to immature hepatic function. Clinical context: Steady state is achieved within 12-24 hours with repeated application.
Terminal half-life: 40-60 minutes (rapidly metabolized by plasma pseudocholinesterase); clinical context: prolonged with hepatic dysfunction or atypical pseudocholinesterase
Lidocaine and prilocaine are metabolized in the liver; lidocaine metabolites (primarily 4-hydroxyxylidine) and prilocaine metabolites (primarily o-toluidine) are excreted renally. Less than 5% of unchanged lidocaine and prilocaine are excreted unchanged in urine. Fecal excretion is negligible.
Renal: 90-95% as unchanged drug and metabolites (predominantly 4-hydroxypropycaine); biliary/fecal: <5%
Category C
Category C
Local Anesthetic
Local Anesthetic