Tobramycin Absorption from the Peritoneal Cavity

Previous studies have found serum tobramycin concentrations greater than 8 mg1L among patients undergoing treatment for peritonitis using hourly dialysate exchanges containing 10 mg1L of tobramycin. In this study, tobramycin absorption from the peritoneal cavity was evaluated among patients treated with exchanges of 180 min. intraperitoneal duration. Six patients in each group were studied. Mass transfer coefficients [MTC (mLI min.)] were calculated for noninfected (C) and peritonitis (P) periods. The mean MTC for C was 6.5 ± 2.1 (SD) mLlmin., and for P, 18.5 ± 8.2 (SD) mLlmin. (p < 0.01). Peritonitis increased the rate of uptake from the peritoneal cavity. In these acute studies, the total dose of tobramycin delivered was small, so that serum concentrations remained less than 0.2 mglL among controls and 0.5 mglL among patients with peritonitis. Prolonged exposure to tobramycin, in association with more rapid absorption from the peritoneal cavity, may lead to serum concentrations greater than 8 mgjL.