Aminoglycosides in cystic fibrosis: a descriptive study of current practice in Australia.

AIM: To determine the diversity of clinical practice with respect to aminoglycosides in cystic fibrosis (CF) units within Australia.
METHOD: In April 1999, a questionnaire on the use of aminoglycosides was sent to 30 CF units across Australia. Information was collected about drug selection, dosing, monitoring and toxicity with intravenous administration.
RESULTS: Completed surveys were received from 26 of the 30 units (response rate = 86%) and all units with > 40 patients. Tobramycin was the drug of choice in all but two centres where there was equivalent use of gentamicin and tobramycin. The survey demonstrated a trend in recent years to reduce the number of doses per day with 54% of centres prescribing once daily, 23% twice daily and 23% thrice daily regimens. Initial dosing was generally based on mg/kg per day (mean 8.8, range 7.5-10 mg/kg per day). Dosing by infusion occurred in 11 of 14 units using once-daily dosing and there was equivalent use of bolus and infusion methods for multiple-daily regimens. Drug monitoring depended on dosing regimen. Units using multiple daily regimens monitored using trough +/- peak levels, whereas 50% of units using once-daily dosing used two postdose levels to alter dose. Actual toxicity, in particular nephrotoxicity, ototoxicity and vestibular toxicity was reported by 19, 27 and 12% of units, respectively.
CONCLUSION: The prescribing, dosing and monitoring of aminoglycosides in CF across Australia varies greatly. This is likely to be due to a lack of definitive evidence as to the optimum use in this patient group.