Do large volume spacer devices reduce the systemic effects of high dose inhaled corticosteroids?

When used in high doses, inhaled corticosteroids may cause suppression of the hypothalamo-pituitary-adrenal axis. The influence of the mode of drug inhalation on the degree of this suppression is not clear. Hypothalamo-pituitary-adrenal function was assessed by measurement of 0900 h serum cortisol concentrations, a short tetracosactrin test, and 24 hour urine free cortisol excretion in 48 adults with asthma taking 1500-2500 micrograms beclomethasone dipropionate daily via a metered dose aerosol. Twelve patients had hypothalamo-pituitary-adrenal suppression, as judged by subnormal results from at least two of the three tests or (in one patient) by an abnormal insulin stress test response. These patients then changed to inhaling the same dose of beclomethasone dipropionate through a 750 ml spacer device (Volumatic). The endocrine tests were repeated from nine days to eight weeks later in 10 patients. Comparison with initial values showed that adding the spacing device caused an increase in the median 0900 h cortisol concentration from 126 nmol/l to 398 nmol/l, in the post-tetracosactrin cortisol concentration from 402 nmol/l to 613 nmol/l and in 24 hour urine free cortisol excretion from 54 nmol to 84 nmol. The rise in serum cortisol concentration in response to tetracosactrin did not change. Evidence of persisting hypothalamo-pituitary-adrenal axis suppression was present in only four of the 10 patients; the most pronounced improvements in function tended to occur in those who had never required long term oral corticosteroids. The results from this uncontrolled study suggest that asthmatic patients taking high dose beclomethasone dipropionate may minimise adverse effects by using a large volume spacer device.