A pilot study to investigate the pulmonary effects of digoxin in patients with asthma

A number of studies have shown that increased salt intake is associated with worsening asthma. The aim of this study was to investigate the respiratory effects of digoxin (a potent inhibitor of Na+K+ATPase) in patients with asthma.

Eight asthmatic patients were given digoxin (0.5 mg/daily) or matching placebo for 8 days. Treatments were assigned using a randomised double blind, crossover design. Bronchial hyperresponsiveness to methacholine, forced expiratory volume is one second (FEV1, serum potassium (K), urinary sodium and K, heart rate, blood pressure and the QTc interval of the ECG were measured on each treatment.

When compared to placebo, digoxin significantly decreased FEV1 (p<0.03); the QTc interval (p<0.05), and increased serum K (p<0.02). There was a tendency for digoxin to increase bronchial hyperresponsiveness.

In this small study digoxin resulted in a decline in spirometry. Further studies in a larger group of patients should be performed to assess this potentially adverse effect of digoxin.