Effect of inhaled amiloride on water-induced bronchoconstriction in asthmatic children

To determine whether the inhaled diuretic, amiloride, can modify bronchoconstriction induced by ultrasonically nebulized distilled water (UNDW) in asthmatic children, a double-blind, randomized, placebo-controlled study was done. The UNDW inhalation challenge was performed in 12 asthmatic children (nine boys and three girls; mean age +/- SEM, 11.2 +/- 0.75 yr), who had at least a 20% fall in FEV1 after UNDW inhalation. On separate days, these subjects underwent UNDW inhalation challenge after inhalation of amiloride (0.3 mg/m2 body surface area) or placebo (0.9% saline). Neither bronchodilation nor bronchoconstriction after amiloride inhalation was observed. The mean value and SEM of the UNDW PD20 after placebo inhalation was 4.55 +/- 0.80 ml. After inhalation of amiloride, PD20 increased to 7.93 +/- 0.75 ml (p < 0.01). We concluded that inhaled amiloride exerted a protective effect against UNDW-induced bronchoconstriction in asthmatic children.