Falsely elevated serum tobramycin concentrations in cystic fibrosis patients treated with concurrent intravenous and inhaled tobramycin

A recently developed tobramycin preparation for inhalation (TOBI(R), Pathog enesis Corp., Seattle, WA) is widely used in GF patients. It is often used in conjunction with intravenous tobramycin. Renal and ototoxicity associate d with the use of tobramycin require that serum drug concentrations be moni tored during therapy. We report on two patients with falsely elevated, toxi c serum tobramycin concentrations while receiving concurrent intravenous an d inhaled tobramycin. These cases point out the need for guidelines governi ng the use and monitoring of simultaneous inhaled and intravenous tobramyci n therapy. (C) 2000 Wiley-Liss, Inc.