Efficacy and Safety of Lidocaine–Prilocaine Cream for Pain during Circumcision

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Abstract
Neonatal circumcision is a painful surgical procedure often performed without analgesia. We assessed the efficacy and safety of 5 percent lidocaine–prilocaine cream (Emla) in neonates undergoing circumcision. We carried out a double-blind, randomized, controlled trial in 68 full-term male neonates: 38 were assigned to receive lidocaine–prilocaine cream, and 30 to receive placebo. One gram of lidocaine–prilocaine or placebo cream was applied to the penis under an occlusive dressing for 60 to 80 minutes before circumcision. Behavioral (facial activity and time spent crying) and physiologic (heart rate and blood pressure) responses were recorded during the procedure. Blood samples were obtained at various times after drug application for measurements of methemoglobin and plasma lidocaine, prilocaine, and o -toluidine (a metabolite of prilocaine). A total of 68 and 59 neonates were included in the safety and efficacy analyses, respectively. Demographic characteristics such as gestational age and birth weight did not differ between the lidocaine–prilocaine and placebo groups. During circumcision, the neonates in the lidocaine–prilocaine group had less facial activity (P = 0.01), spent less time crying (P<0.001), and had smaller increases in heart rate (P = 0.007) than the neonates in the placebo group. Facial-activity scores were 12 to 49 percent lower during various steps of the procedure in the lidocaine–prilocaine group. As compared with neonates in the placebo group, infants in the lidocaine–prilocaine group cried less than half as much and had heart-rate increases of 10 beats per minute less. Blood methemoglobin concentrations (expressed as a percentage of the hemoglobin concentration) were similar (1.3 percent) in both groups. Lidocaine and prilocaine were detected in plasma in 23 (61 percent) and 21 (55 percent) of the infants treated with lidocaine–prilocaine cream, respectively. Lidocaine–prilocaine cream is efficacious and safe for the prevention of pain from circumcision in neonates.