Interstitial concentration of antibiotics and their significance for an adequate dosage

The pharmacokinetic characteristics of the parenteral cephalosporins, cephalothin, cefazolin, cephradine, cefamandole, cefuroxime and cefotaxime (HR-756) were compared applying six different pharmacokinetic points of view. In interpreting antibiotic concentrations measured in soft tissue interstitial fluid (STIF), special attention was paid to the following parameters: cross-point; serum to STIF (AUC) ratio before and after cross-point; STIF half-life time (T 1/2); half-life time area under the curve (AUC) correlated to total STIF area as a percentage and total STIF area under the curve (AUC) measured in micrograms per four hours. The test substances were given to dogs as a single-dose intravenous bolus injection of 20 microgram/kg bodyweight. The investigations resulted in a different order of precedence according to the pharmacokinetic viewpoint applied. Pharmacokinetic parameters are discussed on the basis of the results of this study indicating a more rational antibiotic treatment regimen which is very important in the perioperative prophylaxis of wound infection.