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Single-dose, placebo-controlled comparative study of ibuprofen and acetaminophen antipyresis in children
J T Wilson1, R D Brown, G L Kearns
1Department of Pharmacology, Louisiana State University Medical Center, Shreveport 71130.
Insights
Ibuprofen dosage impacts fever reduction in children. Higher doses and initial temperature significantly influence antipyretic efficacy, revealing nonlinear pharmacodynamics in fever management.
Area of Science:
- Pediatric Pharmacology
- Pharmacodynamics
- Clinical Trials
Background:
- Fever management in children is crucial.
- Understanding antipyretic drug efficacy and influencing factors is essential for optimal treatment.
- Previous studies may not have fully appreciated the impact of initial temperature on drug response.
Purpose of the Study:
- To evaluate ibuprofen as an antipyretic in children aged 3 months to 12 years.
- To compare different ibuprofen dosages (5 vs 10 mg/kg) and its efficacy against acetaminophen.
- To identify confounding variables, particularly initial temperature and age, affecting antipyretic response.
Main Methods:
- A randomized controlled trial involving 178 children with varying initial temperatures.
- Dosage comparison (5 mg/kg vs 10 mg/kg ibuprofen) and placebo control.
- Utilized area under the curve for temperature change to quantify net drug effect.
- Analyzed correlation between initial temperature, age, and antipyretic efficacy.
Main Results:
- Ibuprofen 10 mg/kg demonstrated greater efficacy than 5 mg/kg in febrile children.
- Ibuprofen 5 mg/kg showed minimal effect in younger children with lower initial fevers.
- A significant linear correlation was observed between initial temperature and antipyretic efficacy.
- Initial temperature was identified as the most critical variable, with a twofold increase in efficacy for temperatures below 38.8°C.
Conclusions:
- Initial temperature is the paramount variable in antipyretic study design.
- The magnitude of response to antipyretics is significantly influenced by baseline temperature, a finding termed nonlinear pharmacodynamics.
- Age also exerts a confounding effect on antipyretic response, necessitating further investigation into complex interactions.
Abstract:
Ibuprofen was evaluated as an antipyretic agent in 178 children (aged 3 months to 12 years) to compare dosage (5 vs 10 mg/kg), establish absolute efficacy (with a placebo control group), determine relative efficacy (ibuprofen vs acetaminophen), evaluate maximum efficacy, and identify potential confounding variables. Ibuprofen 5 mg/kg was minimally effective in children less than 6 years of age who had an initial temperature of at least 38.8 degrees C (101.9 degrees F). Ibuprofen 10 mg/kg was more effective for febrile children. The area under the curve for temperature (or change in temperature) captured the net effect of each drug and provided the best estimate for efficacy comparison during a defined period. A linear correlation between initial temperature and measures of efficacy was observed. A twofold increase in efficacy was observed for children with an initial temperature less than 38.8 degrees C. A similar effect was noted for each treatment group. Age was also found to have confounding effects on antipyretic response. A complex interaction between antipyretic response, initial temperature, and age raises questions about the pharmacodynamics of the antipyretic response. We conclude that the most important variable in antipyretic study design is initial temperature. The influence of initial temperature on the magnitude of the response to an antipyretic drug is a previously unappreciated finding with potential impact on pharmacodynamic investigations of antipyretic medications. We describe this finding as nonlinear pharmacodynamics.