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

Abstract

A recently developed tobramycin preparation for inhalation (TOBI®, Pathogenesis Corp., Seattle, WA) is widely used in CF patients. It is often used in conjunction with intravenous tobramycin. Renal and ototoxicity associated with the use of tobramycin require that serum drug concentrations be monitored during therapy. We report on two patients with falsely elevated, toxic serum tobramycin concentrations while receiving concurrent intravenous and inhaled tobramycin. These cases point out the need for guidelines governing the use and monitoring of simultaneous inhaled and intravenous tobramycin therapy.