Abstract

BACKGROUND: In a previous single dosing study in asthmatic school children fluticasone propionate produced significantly greater suppression of overnight urinary cortisol excretion than budesonide at high doses of 800 micrograms/day or greater. The aim of this study was to assess whether conventional lower doses of both drugs cause adrenal suppression when given at steady state twice daily by large volume spacer on a microgram equivalent basis in asthmatic school children. METHODS: Eight school children of mean age 12.1 years with stable asthma of mild to moderate severity (forced expiratory volume in one second (FEV1) 78.6% predicted, mid forced expiratory flow rate (FEF25-75) 72.5% predicted), on 400 micrograms/day or less of inhaled corticosteroid, were studied in a single blind (investigator blind), placebo controlled, crossover design comparing inhaled budesonide and fluticasone propionate 100 micrograms bid and 200 micrograms bid. Each dose was given at 08.00 hours and 20.00 hours for four days by metered dose inhaler via their respective large volume spacers with mouth rinsing. Measurements were made of overnight urinary cortisol and creatinine excretion after the eighth dose. RESULTS: Neither drug produced significant suppression of overnight urinary cortisol or cortisol/creatinine excretion compared with pooled placebo and there were no differences between the drugs. Only one subject with each drug at 200 micrograms twice daily had abnormally low urinary cortisol excretion of < 10 nmol/12 hours. Ratios for the fold difference between active treatment versus placebo for urinary cortisol excretion were (as means and 95% confidence intervals for difference): budesonide 100 micrograms b.i.d 1.03 (95% CI 0.46 to 1.61), budesonide 200 micrograms b.i.d 1.04 (95% CI 0.62 to 1.46); fluticasone 100 micrograms b.i.d 1.11 (0.45 to 1.77), fluticasone 200 micrograms b.i.d 1.12 (0.78 to 1.47). Likewise, there were no significant differences in overnight urinary cortisol/creatinine excretion. CONCLUSIONS: With repeated twice daily administration at steady state across a dose range of 200-400 micrograms/day no evidence of significant adrenal suppression was found using the sensitive marker of overnight urinary cortisol excretion for either fluticasone propionate or budesonide given via a large volume spacer. These results emphasise the good safety profile in children of these inhaled steroids at conventional dose levels, which have proven antiasthmatic efficacy.