Dermal effects and pharmacokinetic evaluation of the lidocaine/prilocaine cream in healthy Chinese volunteers.

Background: EMLA cream is a local anesthetic. The pharmacokinetics and dermal effects of a topical anesthetic formulation has not been evaluated in healthy Chinese volunteers.

Materials and methods: The Pharmacokinetics of the lidocaine/prilocaine test (T) or reference (R, EMLA) cream were evaluated in a fasting, single-dose, two-period crossover bioequivalent study conducted in 40 healthy Chinese volunteers. Meanwhile, the dermal effects including blanching, erythema, temperature sensation, edema, and skin rash were also evaluated during the study.

Results: After applied 15 g of the cream for 4 h to a 100 cm² area under plastic occlusive film on the skin of the thigh of healthy volunteers, the results of the pharmacokinetic study showed that the active components absorbed in skin from topical products was relatively low compared with most system absorption drugs. After the removal of the residual anesthetic cream, there was a vascular biphasic response with initial transient blanching which reaches a peak at 4.5 h and later more persisting period erythema. The change of temperature sensory sensitivity reached the peak value at 4.5-6 h.There was no statistically significant difference of the changes after application the lidocaine/prilocaine T or R cream in subjects. In general, the lidocaine/prilocaine T or R cream was well tolerated.

Conclusion: The method described a model for investigations of pharmacokinetics and pharmacodynamics of topical lidocaine/prilocaine cream. Except the plasma drug level indicator, these pharmacodynamics data should also be evaluated in the anesthetic transdermal pharmacokinetics study.

Clinical trial registration: CTR20211544; registered in http://www.chinadrugtrials.org.cn/ at September 2021.