Pharmacokinetics of Once-Daily Ip Gentamicin in Capd Patients

Abstract

Objective This study aimed to investigate the pharmacokinetic characteristics of once-daily intraperitoneal (IP) gentamicin in continuous ambulatory peritoneal dialysis (CAPD) patients. Design Prospective, nonrandomized, open study. Setting CAPD outpatient clinic in a teaching hospital. Patients Ten volunteer CAPD patients without peritonitis. Interventions Each patient received a single IP dose of 0.6 mg/kg of gentamicin. Blood and dialysate samples were collected at 0,0.5,1, 2, 3,6 (end of first dwell), and 24 hours after the administration of IP gentamicin. Any urine produced over the 24hour study period was also collected. The dialysate concentration/time data were fitted to a monoexponential curve for all patients. Results The bioavailability was 56±11% over a six hour dwell. The mean serum elimination half-life (t1/2) was 35.8 hours. The volume of distribution was 0.23±0.08 L/kg. Equilibration of gentamicin across the peritoneal membrane was rapid, with a t½ equilibration of 4.5 hours. The peritoneal clearance was 5.74±1.5 mL/min. Patients with residual renal function had significantly higher systemic gentamicin clearances (7.36±1.46 mL/min) than those of anuric patients (4.76±1.08 mL/min, p < 0.024). Conclusion Currently recommended doses of oncedaily IP gentamicin for the treatment of peritonitis may not produce the desired therapeutic serum and dialysate concentrations over 24 hours for effective treatment of peritonitis.