Comparative Pharmacology
Head-to-head clinical analysis: EMLA versus NOVOCAIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: EMLA versus NOVOCAIN.
EMLA vs NOVOCAIN
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.
Procaine, an ester-type local anesthetic, reversibly binds to the intracellular portion of voltage-gated sodium channels, inhibiting sodium influx and blocking nerve impulse conduction.
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.
Local infiltration: 0.5% solution, up to 20 mL (100 mg) per dose; nerve block: 1-2% solution, 5-10 mL (50-200 mg); maximum single dose: 7 mg/kg or 350 mg (without epinephrine).
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.
Plasma half-life: approximately 30–60 seconds due to rapid hydrolysis by pseudocholinesterases; clinical effects short-lived.
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 excretion of para-aminobenzoic acid (PABA) and diethylaminoethanol as major metabolites; <2% excreted unchanged in urine. Biliary/fecal: minimal.
Category C
Category C
Local Anesthetic
Local Anesthetic