Pharmacokinetics of cefaclor and cephalexin: dosage nomograms for impaired renal function.
The pharmacokinetics of cefaclor and cephalexin were characterized in patients with creatinine clearances ranging from 0 to 147 ml/min. Each of 24 fasted subjects received a single 500-mg oral dose of cefaclor, and 13 of these subjects later received 500 mg of cephalexin. Serum and urine levels of the antibiotics were measured by bioassay. The serum half-lives were highly correlated with corrected creatinine clearance (cefaclor r = 0.92, cephalexin r = 0.94). Linear regression estimates of the half-life of cefaclor were 2.3 h in the anephric patient and 40 min in the patient with a corrected creatinine clearance of 100 ml/min. For cephalexin, corresponding half-lives were 15.4 h and 58 min. We present a dosage nomogram for calculating the appropriate adjustments to the loading dose based on patient weight and maintenence dose based on corrected creatinine clearance.
D000328:Adult; D000368:Aged; D002506:Cephalexin / Q000008:administration & dosage / Q000378:metabolism*; D002511:Cephalosporins / Q000008:administration & dosage / Q000378:metabolism*; D004334:Drug Administration Schedule; D006207:Half-Life; D006801:Humans; D007674:Kidney Diseases / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008875:Middle Aged
D002511:Cephalosporins; D002506:Cephalexin