Nebulization of corticosteroids to asthmatic children: large variation in dose inhaled

Despite problems associated with assessing the clinical effect and side effects of nebulized corticosteroids, little is known of the amount of drug that is inhaled by children with asthma or how this is affected by different drug formulations. The aim of this study was to test the hypothesis that children with asthma inhale the same proportion of the prescribed dose of nebulized fluticasone, beclomethasone dipropionate (BDP) and flunisolide.

The amount of nebulized drug that would have been inhaled by asthmatic children was captured on filters between the patient and nebulizer, and the amount contained in particles likely to reach the lung (i.e. <5 μm) is determined.

The children studied would have inhaled 13% of the prescribed dose of fluticasone propionate, 21% of BDP and 25% of flunisolide. However, the percentage of the dose inhaled that was contained in particles <5 μm, and therefore more likely to reach the lungs, was only 5% of the prescribed dose of fluticasone propionate, 8% for BDP and 16% for flunisolide. The inter-subject variation coefficient of the dose inhaled was much greater for suspensions of fluticasone propionate (34%) and BDP (45%) than for suspensions of flunisolide solution (9%).

Our results demonstrate that the prescribed dose may bear little resemblance to the dose delivered from a nebulizer and that the dose inhaled is significantly affected by the drug formulation prescribed.