| Abstract: | The plasma propranolol levels associated with the abolition of chronic, stable ventricular ectopic beats have been studied. Racemic propranolol (DL) suppressed the ectopic foci at plasma levels of 40-85 ng/ml in eight patients, but levels of 70-200 ng/ml were unsuccessful in four patients. Dextro-(D) propranolol levels of 180-310 ng/ml were ineffective in four patients who had previously responded at levels of 60-75 ng/ml of racemic propranolol. The significance of the sympathetic nervous system in the genesis of ectopic beats is discussed. It is concluded that propranolol is clinically effective by virtue of its beta-adrenergic blocking activity. |
