Clinical pharmacology of the new beta-adrenergic blocking drugs. Part 5. Pindolol (LB-46) therapy for supraventricular arrhythmia: a viable alternative to propranolol in patients with bronchospasm

Abstract

Pindolol (LB-46) is a new beta-adrenoceptor blocking agent with intrinsic sympathomimetic activity. In order to evaluate the efficacy of pindolol in the treatment of patients with supraventricular arrhythmias and propranolol-induced bronchospasm, 18 patients with paroxysmal supraventricular tachycardia, atrial fibrillation, atrial flutter, multifocal atrial tachycardia or junctional tachycardia, were treated with placebo followed by pindolol in intravenous and then oral form. Following a no-response placebo period (in all patients), intravenous pindolol converted six out of seven patients with paroxysmal supraventricular tachycardia to normal sinus rhythm. In six patients with atrial fibrillation, three reverted to normal sinus rhythm, and three remained in atrial fibrillation but with a slower ventricular response (less than 100 beats/minute). Of two patients with atrial flutter, one converted to normal sinus rhythm, while the other patient failed to respond. Both patients with junctional tachycardia and one with multifocal atrial tachycardia converted to normal sinus rhythm. Long-term oral pindolol therapy sustained these responses in most patients, as documented by serial Holter ECG studies. There was no deterioration in indices of airway resistance ($\text{FEV}{}_{\mathrm{1·0}}\text{VC}$) in patients treated with pindolol (both intravenously and orally), in contrast to a marked deterioration in $\text{FEV}{}_{\mathrm{1·0}}\text{VC}$ in the same patients treated with propranolol. Pindolol appears to be a reasonable substitute for propranolol in patients with bronchospastic illness who require beta-blockade for control of supraventricular arrhythmias.