Pharmacokinetics of EMLA cream 5% application to oral mucosa.

Plasma concentrations of lidocaine and prilocaine were measured following the application of a 5% eutectic mixture of local anesthetics (EMLA) topical anesthetic cream to the oral mucosa of twelve subjects. For each subject, a total of 8 g of EMLA was occluded to 18 cm2 of buccal mucosa for 30 min. Analysis was carried out by high-pressure liquid chromatography, and results showed peak concentrations at 40 min for lidocaine and prilocaine. The maximum concentration measured in any subject was 418 ng/ml for lidocaine and 223 ng/ml for prilocaine, well below known toxic levels. No adverse local effects were observed from a 30-min application of EMLA. A follow-up pilot study assessing the clinical efficacy of EMLA for achieving sufficient analgesia for restorative procedures showed that the cream was successful in 75% of subjects tested.