Abstract
Objectives: Correct use of inhaler devices is critical in
ensuring the optimal lung bioavailability of the inhaled drug. The study
aimed to assess inhaler technique used in patients with using
metered-dose inhalers (MDI) by correlating with urinary salbutamol
excretion post inhalation and its correlation with disease control.
Methods : Thirty patients with obstructive pulmonary diseases
attending outpatients’ services inhaled two doses of salbutamol 100 µg
and urine samples were collected after 30 min. Inhaler technique scores
were assessed using a standardized 8-point checklist. The 30-minute
concentration of urinary salbutamol is then correlated with inhaler
technique scores and control status of the disease.
Key findings : The mean age of the subjects was 60.8 (SD ±
9.338). The mean (SD) 30 min urinary salbutamol concentration was
3.6±1.6 µg/ml. The mean concentration of salbutamol was found to be 2.3
µg/ml (n=1), 2.3 µg/ml (n=5), 3.1 µg/ml (n=7), 3.9 µg/ml (n=8), 4.7
µg/ml (n=5), 5.3 µg/ml (n=3), and 5.0 µg/ml (n=1) among patients
performing 1, 2, 3, 4, 5, 6, 7, 8 steps correctly, respectively. There
was a statistically significant correlation (p=0.028) witnessed between
the mean 30 min urinary salbutamol concentration and total correct
steps. The frequency of exacerbation, use of antibiotics, and oral
corticosteroids (OCS) were more in patients with poor inhaler technique
scores, although statistical significance was achieved only for
frequency of antibiotics use (p=0.032).
Conclusions : The 30 min salbutamol urinary concentration
evaluation may help to identify patients who were underdosed due to poor
handling of inhaler devices. Being a complex procedure, it can at least
be initiated in patients reporting frequent exacerbations,
hospitalization, and those who need multiple drugs for disease control.
Keywords : obstructive pulmonary disease; optimal inhaler
technique; metered inhaler device; urinary salbutamol concentration;
disease control.