RESUMO
BACKGROUND: We have previously shown that in patients with asthma a single dose of an inhaled glucocorticosteroid (ICS) acutely potentiates inhaled albuterol-induced airway vascular smooth muscle relaxation through a nongenomic action. An effect on airway smooth muscle was not seen, presumably because the patients had normal lung function. The purpose of the present study was to conduct a similar study in patients with asthma with airflow obstruction to determine if an ICS could acutely also potentiate albuterol-induced airway smooth muscle relaxation in them. METHODS: In 15 adult patients with asthma (mean ± SE baseline FEV1, 62% ± 3%), the response to inhaled albuterol (180 µg) was assessed by determining the change in FEV1 (ΔFEV1) for airway smooth muscle and in airway blood flow (ΔQaw) for airway vascular smooth muscle measured 15 min after drug inhalation. Using a double-blind design, the patients inhaled a single dose of the ICS mometasone (400 µg) or placebo simultaneously with or 30 min before albuterol inhalation. RESULTS: After simultaneous drug administration, mean ΔFEV1 was 0.20 ± 0.05 L (10%) after placebo and 0.32 ± 0.04 L (19%) after mometasone (P < .05); mean ΔQaw was -2% after placebo and 30% after mometasone (P < .005). When mometasone or placebo was administered 30 min before albuterol, there was a lesser and insignificant difference in ΔFEV1 between the two treatments, whereas the difference in ΔQaw remained significant. CONCLUSIONS: This pilot study showed that in adult patients with asthma with airflow obstruction, a single standard dose of an ICS can acutely increase the FEV1 response to a standard dose of inhaled albuterol administered simultaneously. The associated potentiation of albuterol-induced vasodilation in the airway was of greater magnitude and retained when the ICS was administered 30 min before albuterol. The clinical significance of this observation will have to be established by a study involving a larger patient cohort. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01210170; URL: www.clinicaltrials.gov.
