Pharmacokinetics of piperacillin in hospitalized patients

Piperacillin is an extended-spectrum penicillin active against Pseudomonas. It has been documented to be effective in the treatment of complicated urinary tract infections and urosepsis. Much of the pharmacokinetic information available is obtained from normal subjects. The purpose of this study is to evaluate piperacillin pharmacokinetics in hospitalized patients. Ten clinically stable hospitalized urology patients were given 4 grams of piperacillin intravenously in a single dose. Serial blood samples were then obtained and serum piperacillin concentrations were determined by high performance liquid chromatography. The following pharmacokinetic parameters (mean +/- SD) were determined: half-life = 1.09 +/- 0.31 h, elimination rate constant = 0.69 +/- 0.22 h-1, volume of distribution = 0.36 +/- 0.13 l/kg, total body clearance = 0.230 +/- 0.054 l/h/kg. These parameters are comparable to those obtained in normal subjects except for the volume of distribution which is slightly higher than that reported in healthy volunteers. Pharmacokinetic information obtained in healthy subjects may, therefore, be applied to the clinically stable hospitalized urology patient. However, changes in pharmacokinetic characteristics may be found in the critically ill patient with compromise in hemodynamics and significant third spacing of fluid.