Clinical trial with a beta-receptor antagonist (propranolol) in parkinsonism.

Pronethalol (Alderlin), an adrenergic beta-blocking agent introduced in 1963, was successfully tested in the management of various cardiac arrythmias, phaeochromocytoma, angina pectoris, and hypertension. Herring (1964) administered the drug to 10 patients with Parkinsonism, in view of the well known 'tremor-potentiating effect' of adrenaline, and observed a diminution of tremor following an intravenous dose of 50 mg. Due to the subsequent detection of carcinogenic changes in mice, although not in rats, Alderlin was withdrawn and replaced by the chemically similar, but non-toxic preparation propranolol, which was the drug employed in the present trial. Propranolol (Inderal), 1-isopropylamino-3-(1naphthyloxy)-2-propanol-hydrochloride, is an adrenergic, beta-receptor antagonist, having 10-20 times the therapeutic ratio of Alderlin. It is available as 10 mg. scored tablets and in 5 mg. ampoules for intravenous injection and possesses the following structural formula: