Practical pharmacokinetic techniques for drug consultation and evaluation. IV: Gentamicin blood level versus time profiles of various dosage regimens recommended for renal impairment.

The gentamicin blood level vs. time profiles of various dosage regimens recommended for renal impairment were reassessed by applying pharmacokinetic techniques to the patient data in the clinical literature. Eight dosage regimen modifications were tested in eight prototype cases of renal impairment (serum creatinine range of 0.9-12.0 mg/100 ml and creatinine clearance range of 5-100 ml/min/1.73 m-2) using simulated blood level vs. time profiles generated from the known pharmacokinetic parameters for gentamicin. Employing a one-hour intravenous infusion at dosages and dosing intervals recommended by the various blood level vs. time profiles. Methods recommending shorter dosing intervals (every 24 hours and less) generally resulted in a greater percent duration of the dosing interval above the selected "effective response concentration" (ERC) of a 4mug/ml blood level and a markedly shorter duration of sub-ERC blood levels. Methods based on creatinine clearance as an index of renal function generally achieved greater percent duration of the dosing interval above the ERC and lesser duration of blood levels below this value than methods based on serum creatinine.