Effects of renal failure and dialysis on cefazolin pharmacokinetics

Serum and urinary levels of cefazolin, were determined after a 500 mg parenteral dose in eight azotemic volunteers. The mean peak serum concentration was 1.5 to 5 times the levels obtained in nonazotemic patients. The serum half life of cefazolin was increased significantly. In patients on dialysis, the mean serum half life of cefazolin was 4.05 h during (or after) hemodialysis, and 32.1 h during (or after) peritoneal dialysis. There was a significant decrease in cefazolin removal when dialysis flow or membrane surface area of the dialyzer were decreased. It was also shown that one circuit through the dialysis unit caused measurable decrease in cefazolin concentration. These data and previously published suggest: (i) the maintenance dose of cefazolin can be decreased in azotemic patients; (ii) patients on hemodialysis will require an additional half dose after dialysis because of efficient removal during hemodialysis; and (ii) patients on peritoneal dialysis do not require an extra dose.