Plasma concentrations of lidocaine and prilocaine and analgesic effect after dermal application of EMLA cream 5% for surgical removal of mollusca in children.

Abstract

The plasma concentrations of lidocaine and prilocaine after dermal application of EMLA cream 5% were determined in two clinical studies. The cream (10-16 g) was applied to a total surface area of 100-160 cm2. Each area was covered by a Tegaderm dressing (3M) in order to obtain occlusion. An application time of 2 hours was used. Two age groups of ten children were studied: 2-3 years and 6-8 years. In both groups venous blood samples were drawn prior to application and at 2, 3, 4 and 5 hours. In addition, in one of the studies, the cream was used during the surgical removal of mollusca in order to study the analgesic effect of the cream. The absorption of the local anaesthetics as indicated by plasma concentrations was far below toxic levels. The highest individual concentration of lidocaine was 315 ng/ml and of prilocaine 215 ng/ml. The analgesic effect was sufficient--eight out of ten patients experienced no or slight pain. Transient local reactions (paleness, redness) were frequently observed. In one patient with eczema present at the application site prior to the application, a reaction persisted for one week. Dermal analgesia provided by EMLA is a safe and effective method for alleviation of pain from removal of mollusca and the plasma concentrations are innocuous.