Gentamicin concentrations in urine, cortex and medulla in an acutely obstructed kidney animal model

Gentamicin was administered intraperitoneally, three times in 12 h to Hartley type guinea-pigs which had undergone complete unilateral ureteral obstruction with normal contralateral ureteral function for either 24 hours, 7 days or 21 days. Two hours after the last drug dose urine samples were collected from urinary bladder and obstructed ureter. Healthy and obstructed kidneys were then surgically removed from all sacrificed animals. Gentamicin concentration in urine of healthy kidney was 112-266 microg/ml, and in obstructed kidney 18-53 microg/ml, with a tendency of linear decrease over a 3-week obstruction period. The gentamicin concentration in obstructed renal cortex never exceeded one-third of the gentamicin concentration in unobstructed renal cortex. The maximum gentamicin concentration in obstructed renal medulla was 75% of the gentamicin concentration in unobstructed renal medulla.