A pharmacokinetic evaluation of the effect of plasma exchange on tobramycin disposition

The effect of plasma exchange on the disposition of tobramycin was studied in three procedures done on two patients. Serum tobramycin levels were obtained when the subjects were off plasma exchange to calculate individualized tobramycin pharmacokinetic parameters. The amount of drug removed was measured and serum levels were obtained during plasma exchange. The effect of the procedure was evaluated by calculating the percentage of total body stores removed and comparing drug elimination half-life data on and off plasma exchange. The procedures resulted in the removal of 6.1%, 5.9% and 4.3% of total body stores of tobramycin. Plasma exchange provides an additional route of elimination for tobramycin which should be considered when dosing the drug in patients undergoing this procedure.