A survey of extended-interval aminoglycoside dosing practices in United States adult cystic fibrosis programs

INTRODUCTION: The Cystic Fibrosis Foundation recently deemed the use of extended-interval dosing (EID) of aminoglycosides acceptable for the treatment of cystic fibrosis (CF) pulmonary exacerbations. However, current practice across United States adult CF programs and affiliate programs is unknown. The objectives of this research are to characterize the practice trends, dosing strategies, therapeutic drug-monitoring practices, and adverse effect monitoring of the EID of aminoglycosides in the treatment of pulmonary exacerbations across United States adult CF programs. METHODS: A 34-question online survey instrument was distributed on behalf of the author by the United States Cystic Fibrosis Foundation to all United States adult CF programs and affiliate programs. RESULTS: Of the 68 participating adult CF programs (44.4% survey response rate), 64 (94.1%) reported using EID of aminoglycosides (as once-daily or twice-daily dosing). More than 95% of programs reported frequently or always using this dosing method. Tobramycin dosed 10 mg/kg/d every 24 h, infused over 3 0 -6 0 min, was the most commonly cited regimen. Monitoring of aminoglycoside serum concentrations was reported by all programs, with a tobramycin peak of 25-30 mg/L and trough of < 1 mg/L targeted most frequently. Nephrotoxicity was commonly monitored through serum creatinine measurements, while ototoxicity was monitored by audiometry in approximately one-half of programs. CONCLUSIONS: This study indicates that the use of EID of aminoglycosides across United States adult CF programs has increased considerably since the publication of the CF pulmonary exacerbation guidelines and now appears to be the most common method for dosing aminoglycosides in adults with CF.