Author(s): Gary N Gross
A 45 yr old woman who was incapacitated by severe exercise induced asthma is presented. Phentolamine, a drug with α adrenergic blocking properties significantly reduced after exercise bronchospasm, which had been uncontrolled by treatment with xanthines, antihistamines, ephedrine, steroids, isoproterenol and cromolyn sodium. Using a double blind protocol, blocking of exercise induced bronchospasm was demonstrated by both acute inhalation of phentolamine, 5 mg, and longterm oral administration of phentolamine, 300 mg/day. Two right heart catheterizations, one performed after placebo for 6 days, the other after orally administered phentolamine for over a mth, showed little difference in her cardiovascular response to exercise, thus suggesting a direct effect of phentolamine on bronchial smooth muscle.