Delivery of beclomethasone dipropionate from a spacer device: what dose is available for inhalation?

Abstract

BACKGROUND--It is common for inhaled steroids to be delivered through a large volume spacer device. Comparatively little is known about how this practice affects the dose of drug received by patients compared with drug delivered directly from a metered dose inhaler. METHODS--The amount of beclomethasone dipropionate, contained in particles of various size, available for inhalation from a 750 ml polycarbonate spacer (Volumatic) was determined by impinger measurement and high performance liquid chromatography. Three strengths of metered dose inhalers were studied (50 micrograms, 100 micrograms, and 250 micrograms/actuation). The effect of multiple actuations of beclomethasone dipropionate into a Volumatic spacer, and increasing residence times of drug within the spacer before inhalation, on the amount of drug available to the patient for inhalation was determined. RESULTS--The amount of beclomethasone dipropionate in particles < 5 microns when delivered by a spacer device or directly from a metered dose inhaler was similar. The total amount of beclomethasone dipropionate available for inhalation per actuation decreased by 20 micrograms with the 50 micrograms inhaler, 48 micrograms with the 100 micrograms inhaler, and 161 micrograms with the 250 micrograms inhaler, when given via the spacer compared with delivery directly from a metered dose inhaler. There was a progressive decrease in drug available for inhalation per actuation as the number of actuations into the spacer increased, for all strengths of beclomethasone dipropionate tested. A progressive decrease in drug recovered per actuation was also seen with increasing residence times of drug within the spacer before inhalation. CONCLUSIONS--Use of the spacer device significantly reduced the amount of nonrespirable beclomethasone dipropionate available for inhalation. The amount of beclomethasone dipropionate within respirable particles decreased considerably following multiple actuations into the spacer and with increasing residence times within the spacer before inhalation. When given via a spacer device beclomethasone dipropionate should be inhaled immediately after actuation and multiple actuations into the device should be avoided.