Penile absorption of EMLA cream in piglets: implications for use of EMLA in neonatal circumcision.

Abstract

EMLA (eutectic mixture of lidocaine and prilocaine) cream is currently not recommended for use in infants < 1 month of age because of the potential risk of methemoglobinemia as a result of the o-toluidine metabolite of prilocaine. We studied bioavailability and changes in methemoglobin levels following topical penile exposure to 1 g of EMLA cream for 1 hour in piglets. Lidocaine, prilocaine, and o-toluidine concentrations were measured simultaneously using a high-performance liquid chromatography method. The systemic bioavailability of EMLA was low: 4.0 +/- (SD) 4.7% for lidocaine (range 0-13.6; n = 8) and 7.2 +/- 5.7% for prilocaine (range 0-14.5; n = 8). The ratio between exposure to o-toluidine with EMLA versus intravenous administration (i.e., AUCEMLA/AUCIV; see text) was also low: 4.2 +/- 9.3% (range 0-28.6; n = 9). The mean maximum methemoglobin value after intravenous administration was 1.23 +/- 0.64% (range 0.5-3.0; n = 12) and after penile application 0.99 +/- 0.36% (range 0.5-2.0; n = 12). The methemoglobin value was elevated significantly above baseline after intravenous administration (p = 0.03), but not after penile application of EMLA. These findings suggest that penile administration of 1 g of EMLA may be safe for neonatal circumcision, but further study is required.

• Authors: M Gazarian, A Taddio, J Klein, G Kent, G Koren
• Journal: Biology of the neonate (Biol Neonate) Vol. 68 Issue 5 Pg. 334-41 ( 1995) ISSN: 0006-3126 [Print] Switzerland
• PMID: 8835088 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anesthetics, Local
• Drug Combinations
• Lidocaine, Prilocaine Drug Combination
• Ointments
• Toluidines
• Prilocaine
• Lidocaine
• 2-toluidine

Topics

• Absorption
• Anesthetics, Local (pharmacokinetics)
• Animals
• Animals, Newborn (metabolism)
• Circumcision, Male
• Cross-Over Studies
• Drug Combinations
• Injections, Intravenous
• Lidocaine (pharmacokinetics)
• Lidocaine, Prilocaine Drug Combination
• Male
• Methemoglobinemia (blood)
• Ointments (pharmacokinetics)
• Penis (metabolism)
• Prilocaine (pharmacokinetics)
• Swine
• Toluidines (metabolism)