Tetracaine versus lidocaine-prilocaine for preventing venipuncture induced pain in children

The efficacy of tetracaine cream versus that of lidocaine-prilocaine cream for the prevention of pain in children undergoing venipuncture was studied. Hospital inpatients 1-15 years of age received, on the back of each hand, a 30-minute application of tetracaine 4% cream or a 60-minute application of lidocaine-prilocaine cream (EMLA, Astra) before undergoing scheduled venipuncture. The phlebotomists in this open, randomized trial evaluated the efficacy of the cream at the moment of venipuncture as adequate, inadequate, or inconclusive. Blood samples were taken immediately after venipuncture from 10 patients one to five years of age to measure the serum concentrations of tetracaine and its metabolite, N-butyl-p-aminobenzoic acid. Lidocaine-prilocaine cream was significantly more efficacious in preventing pain than tetracaine 4% cream (97% of the former group [n = 32] had adequate pain relief, compared with 76% of the latter [n = 34]. The only adverse effects observed were mild local erythema in the tetracaine group and local skin blanching in the lidocaine-prilocaine group. No tetracaine could be detected in serum, and the serum concentrations of N-butyl-p-aminobenzoic acid ranged from 0 to 1.8 mg/L. Statistically, lidocaine-prilocaine cream was more efficacious than tetracaine 4% cream, but the difference is of minor clinical significance and is outweighed by the practical advantages of tetracaine 4% cream, namely the shorter application time, vasodilation and lower cost.