Gentamicin Pharmacokinetics during hemodialysis

Seventeen Subjects on thrice-weekly intermittent hemodialysis were treated with a dose of 40mg gentamicin (GM) (0.6-lmg/kg) given intravenously after each dialysis. Blood samples were withdrawn at 10 minutes after injection, and then before and after each dialysis, and for the calculation of dialyzer clearance blood samples were drawn from dialyzer inlet and outlet tubing after blood flow and transmembranepressure were set at 150-200m1/minutes and 100mmHg. GM concentration was meaured by radioimm-unoassay. 1) Serum levels of GM after the dose and before the next dialysis were 7.2±2.5, 2.4±1.2μg/ml (mean±S. D.) for 43 hours interdialysis period group and 8.0±2.7, 2.2±1.2pg/ml for 67 hours interdialysis period group. 2) Rates of clearance of GM with dialyzers showed wide range of variation from 38 to 138m1/minute depending on the kind of dialyzer tested. Extraction ratio and clearance ratio to creatinine were also varied from 0.33 to 0.61 and from 0.54 to 1.15, respectively. 3) As the GM injection repeated, the predialysis blood levels rose slowly from 0.8±0.6μg/ml after the first dose to 2.1±1.0μg/ml after 5th dose (p