Effect of tolazoline hydrochloride on sputum viscosity in cystic fibrosis

Comparisons have been made between the effects of autonomic dysfunction and the pathophysiological changes in the exocrine secretions from patients with cystic fibrosis (Roberts, 1959). Cotton (1966) found that administration of tolazoline hydrochloride (an alpha-adrenergic blocker) to patients with cor pulmonale in the terminal stages of cystic fibrosis was associated with an improvement in the results of their lung function tests. This effect might have been due to an alteration of the abnormal viscosity of the bronchial mucus mediated via the autonomic nervous system, thus permitting easier expectoration. Measurement, by means of a Ferranti-Shirely cone and plate viscometer, of several different aspects of sputum viscosity is described. Tolazoline hydrochloride, administered to five patients with cystic fibrosis, was shown not to differ significantly from a placebo in its effect on sputum viscosity and dynamic lung volumes. We could not relate the improved lung function seen in Cotton's series to an autonomic effect of the drug on the physical properties of bronchial mucus in this condition.