Variability in derived parameters of furosemide pharmacokinetics

The pharmacokinetics of furosemide in normal man reported from a number of investigators show great discrepancies. We have evaluated the effect on derived pharmacokinetic parameters of furosemide of using different weighting factors or fewer data points to fit the same set of data to an exponential equation, or using noncompartmental analysis. Terminal half-lives of furosemide differed vastly, as did the volume of distribution, but to a lesser extent. The plasma clearance was rather consistent with the different methods used. Thus the discrepancies of the pharmacokinetics of furosemide may, in large part, be due to different methods of analysis of the data. The terminal half-life was most subject to errors of method and the plasma clearance the least.