Comparative Pharmacology
Head-to-head clinical analysis: EMLA versus TETRACAINE HYDROCHLORIDE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: EMLA versus TETRACAINE HYDROCHLORIDE.
EMLA vs TETRACAINE HYDROCHLORIDE
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.
Tetracaine hydrochloride is a local anesthetic of the ester type that reversibly blocks nerve conduction by decreasing sodium ion permeability across the neuronal membrane, thereby stabilizing the membrane and preventing the initiation and transmission 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.
Topical: 0.5-2% solution or ointment applied to affected area up to 4 times daily as needed. Maximum single dose: 20 mL of 2% solution (400 mg). Spinal anesthesia: 0.5% solution, 2-3 mL (10-15 mg) injected intrathecally.
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 elimination half-life is approximately 1.5–3 minutes in plasma due to rapid hydrolysis; clinical effect duration is dose-dependent (15–30 minutes for topical anesthesia).
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.
Primarily metabolized by plasma pseudocholinesterase; renal excretion of metabolites accounts for >95% of elimination, with <2% excreted unchanged in urine. Biliary/fecal elimination is negligible.
Category C
Category C
Local Anesthetic
Local Anesthetic