Estimation of the dose of fluticasone propionate inhaled by infants after bronchiolitis: Effect on urinary cortisol excretion.

Abstract

Information on the dose of steroid infants inhale from spacer devices and its potential effect on adrenal suppression is limited. We sought to determine the total dose of fluticasone propionate (FP) inhaled from a spacer device (Babyhaler) with face mask attachment by infants recovering from acute bronchiolitis and the effect of inhaled FP on the infants' overnight urinary cortisol/creatinine ratios (UCCRs). Infants studied were recovering from acute bronchiolitis. In study 1, 22 infants inhaled 150 microg of FP through the Babyhaler. The likely inhaled dose was estimated by trapping it on a filter held within the face mask. In study 2, 40 infants had UCCRs measured before and during 3 months of treatment with either FP (150 microg twice daily, n = 20) or placebo (n = 20). In study 1 the mean +/- SD dose of captured FP was 12.8 +/- 6.9 microg (ie, 2.1 +/- 1.2 microg/kg). In study 2 the pretreatment UCCR medians (interquartile ranges) were as follows: FP, 22.8 (23.0) nmol/mmol; placebo, 24.0 (28.3) nmol/mmol. Within-group UCCR changes (median and interquartile range DeltaUCCR) were significantly different in the FP group (-8.9 and -20.6 nmol/mmol at 6 weeks and -12.6 and -25.9 nmol/mmol at 12 weeks, respectively; P =.0008) but not in the placebo group ( -5.8 and -10.7 nmol/mmol at 6 weeks and +0.3 and -17.9 nmol/mmol at 12 weeks, respectively; P =.45). Intergroup changes were insignificant in the follow-up period (6 weeks, P =.52; 12 weeks, P =.19). After bronchiolitis, infants are likely to inhale approximately 8 % of the nominal steroid dose from the Babyhaler. UCCRs can be used to monitor the bioavailability of inhaled steroids in young infants.