To determine the effect of dialysate osmolarity on peritoneal dialysis drug transfer, peritoneal dialysis clearances of theophylline, phenobarbital, and tobramycin were determined in 10 rabbits using dialysate containing 1.5 and 4.25% glucose. Urea and creatinine clearances were also obtained for comparison. Under similar dialysis conditions, the peritoneal clearances of the three drugs remained unchanged for the two types of dialysate. In contrast, the peritoneal clearances of urea and creatinine were significantly higher with the use of 4.25 % glucose dialysate (p < 0.001). Thus, peritoneal dialysis clearances of theophylline, phenobarbital and tobramycin are not significantly affected by hypertonicity-induced ultrafiltration during acute peritioneal dialysis.