Fifteen patients with atrioventricular heart block and Adams-Stokes syndrome were treated with oral sustained-action isoproterenol tablets, 30 mg. every 4 to 6 hours. One or more of the following beneficial effects was observed in 13 patients: restoration and maintenance of normal sinus rhythm, increase in the rate of the basic idioventricular pacemaker, stimulation of the faster of two competing idioventricular centers, and stabilization of the idioventricular pacemaker so that ventricular slowing or asystole failed to recur. Side-effects, which were few, consisted of tachycardia, palpitation, or tremor in 4 cases and resulted in discontinuance of the drug in only 2 cases. Oral medication was less apt to produce annoying tachycardia or angina in susceptible individuals than was sublingual isoproterenol.
Dack S, Robbin SR. Treatment of Heart Block and Adams-Stokes Syndrome with Sustained-Action Isoproterenol. JAMA. 1961;176(6):505-512. doi:10.1001/jama.1961.03040190027008