Despite evidence that circumcision is intensely painful for newborns, many physicians are reluctant to administer analgesic medications. In addition to the immediate discomfort of the procedure, the neonate may be unsettled for several hours. Alterations in sleeping, feeding and crying patterns have been associated with the untreated pain of circumcision. In addition, circumcised infants have more pain during routine vaccination at four to six months of age than uncircumcised infants, suggesting that response to the perception of pain in the future may be altered. Taddio and colleagues assessed the effectiveness of a 5 percent lidocaine-prilocaine cream for analgesia during neonatal circumcision.

A total of 68 full-term neonates were enrolled in the double-blind, randomized controlled study. Thirty-eight infants received lidocaine-prilocaine cream for analgesia, and 30 infants received a placebo cream. One gram of lidocaine-prilocaine cream or placebo cream was applied to the penis under an occlusive dressing for 60 to 80 minutes before the procedure. Behavior and physiologic responses during the procedure were observed and measured. Blood samples were taken to measure serum levels of methemoglobin, plasma lidocaine, prilocaine and a metabolite of prilocaine.

Neonates in the lidocaine-prilocaine group demonstrated fewer facial grimaces during the procedure. They cried half as much, and their heartbeat increases were 10 beats per minute less on average. Serum levels of methemoglo-bin concentrations were similar for both groups. Lidocaine and prilocaine were detected in the plasma of most infants in the treatment group, but the levels were low and disappeared after 18 hours. Side effects were limited. Pallor at the application site was noted in 32 percent of the neonates in the lidocaine-prilo-caine group, compared with 13 percent in the placebo group. One neonate in the lidocaine-prilocaine group had mild edema, and one had a local infection that was successfully treated with a topical antibiotic.

The authors conclude that neonates in the lidocaine-prilocaine group experienced pain during circumcision, although it was diminished. The relatively simple method of analgesia described in this study may increase the use of pain medications in infants who undergo circumcision.