Population pharmacokinetic analysis of the active product of dipyrone

Objective: Pharmacokinetics of 4-methyl-amino-antipyrine (MAA), the active metabolite of the nonsteroidal anti-inflammatory agent dipyrone, whose time course correlates to the therapeutic effect of the drug, are studied. Study design and setting: 153 patients hospitalized in the Department of Medicine at the Hadassah University Hospital, Jerusalem, Israel. Intervention: Patients receiving dipyrone for the treatment of fever or pain were asked to participate in the study. Pharmacokinetics and statistical analysis: Using the population approach based on a formerly developed experimental model, the relationships between pharmacokinetic parameters and demographic and physiological covariates are explored. Results: The results of the analysis show considerable variability in pharmacokinetics across the study population, and a significant decrease in clearance with age. Conclusion:Apopulation pharmacokinetic analysis of MAA, the active product of dipyrone, reveals that age is a significant predictor of MAA disposition. Covariates that measure hepatic and renal function do not appear to be good predictors of the rate of MAA disposition.