Background: The exact amount of drug deposited in the respiratory and gastrointestinal tract in children with airway obstruction, when delivered from a metered-dose inhaler (MDI) via a spacer with mask, and its distribution in children with airway obstruction, are unknown.
Methods: We studied 15 children, using salbutamol labeled with technetium 99m. Each patient was imaged with a gamma-camera immediately after one puff of labeled salbutamol was administered via a spacer with mask. Drug deposition was then analyzed to measure the distribution of the labeled spray in the oropharynx, the lungs, the stomach, and the spacer with mask (Aerochamber) itself.
Results: Fifteen infants and children (mean age, 21 months (range, 3 months to 5 years); mean weight, 9.3 kg (range, 3.2 to 15 kg)) were studied. Mean aerosol deposition was 1.97% +/- 1.4% in the lungs, 1.28% +/- 0.77% in the oropharynx, and 1.11% +/- 2.4% in the stomach. The remainder was trapped in the spacer. Lung imaging after inhalation from an MDI via a spacer showed widespread deposition of the drug in central and peripheral intrapulmonary airways. In two adult volunteers the deposition after one puff of the same radiolabeled drug, inhaled from an MDI via a spacer with a mouthpiece, was 19% in the lungs and 2% in the stomach.
Conclusions: Infants and toddlers with obstructive lung disease can be reliably and safely treated with inhaled medication administered with an MDI via a spacer with mask. The doses of a drug given from an MDI to infants and toddlers when a spacer with mask is used are not yet well defined but should be higher than the currently recommended doses, perhaps as much as an adult dose.