Antipyretic Efficacy of an Initial 30-mg/kg Loading Dose of Acetaminophen Versus a 15-mg/kg Maintenance Dose

OBJECTIVE: To compare the antipyretic efficacy of an initial 30-mg/kg acetaminophen loading dose versus a 15-mg/kg maintenance dose. METHODS: A double-blind, parallel-group, randomized clinical trial was conducted. A total of 121 febrile (rectal temperature between 39 degrees C and 40 degrees C) but otherwise healthy outpatients who were 4 months to 9 years of age and weighed 4 to 26 kg were assigned randomly to 1 of the dose groups: 15 mg/kg (n = 62) and 30 mg/kg (n = 59). RESULTS: In an "intention to treat" analysis, the time to obtain a temperature lower than 38.5 degrees C was significantly shorter in the 30-mg/kg than in the 15-mg/kg group (110 +/- 94 minutes vs 139 +/- 113 minutes). The maximum temperature decrease was significantly higher in the 30-mg/kg than in the 15-mg/kg group (2.3 +/- 0.7 degrees C vs 1.7 +/- 0.6 degrees C). Duration of rectal temperature below 38.5 degrees C was significantly longer in the 30-mg/kg than in the 15-mg/kg group (250 +/- 92 minutes vs 185 +/- 121 minutes, respectively). Adverse events were reported in 6 children in the 30-mg/kg group compared with 5 in the 15-mg/kg group (hyperthermia, hypothermia, vomiting). The difference was not statistically significant. CONCLUSION: An initial 30-mg/kg acetaminophen loading dose seemed to be more effective in reducing fever than a 15-mg/kg maintenance dose. No difference was observed regarding clinical tolerance. These data suggest that acetaminophen treatment of fever may be more efficient in an initial loading dose.