Comparison of propranolol and Ro 3-3528 in hyperthyroid tachycardia and dysrhythmias

Abstract

SummaryRo 3-3528, a non-selective 3-adrenoceptor blocking drug which lacks intrinsic activity, produces a doseresponse effect in hyperthyroid tachycardia, and shows no dysrhythmic properties. In hyperthyroid patients,

The ASSESSMENT OF Β‐ADRENOCEPTOR BLOCKING DRUGS IN HYPERTHYROIDISM

“…In the present study, practolol did have a dose-dependent effect on exercise heart rate in hyperthyroid patients. (Turner & Hill, 1968;Turner, 1970;Arbab & Turner, 1971;Phillips et al, 1973). These present observations would suggest that reduction in resting heart rate is not representative of the ,3-blocking activity of these drugs and that, whilst propranolol is obviously more effective than practolol in hyperthyroid patients, this merely reflects the comparable activity of these two drugs in normal subjects, and cannot be held to support the idea that patients with hyperthyroidism are unduly sensitive to the effects of catecholamines.…”

“…This test could be performed easily and, if necessary, frequently, and would avoid the difficulties of carrying out strenuous exercise in the presence of either thyrotoxic myopathy or cardiovascular disease. Further support for the use of such a test to evaluate ,B-adrenoceptor blocking agents in Practolol, and other f-adrenoceptor blocking drugs with intrinsic sympathomimetic activity, have been labelled as inferior to propranolol and other drugs without intrinsic activity in the treatment of hyperthyroidism but only on the basis of their effect on resting heart rate (Turner & Hill, 1968;Turner, 1970;Arbab & Turner, 1971;Phillips et al, 1973). These present observations would suggest that reduction in resting heart rate is not representative of the ,3-blocking activity of these drugs and that, whilst propranolol is obviously more effective than practolol in hyperthyroid patients, this merely reflects the comparable activity of these two drugs in normal subjects, and cannot be held to support the idea that patients with hyperthyroidism are unduly sensitive to the effects of catecholamines.…”

“…The effectiveness and usefulness of other 3-adrenoceptor blocking drug with intrinsic sympawould appear that drugs possessing intrinsic sympathomimetic activity, such as alprenolol, oxprenolol, practolol and pindolol, fail to produce a dose-dependent slowing of hyperthyroid tachycardia (Turner & Hill, 1968;Turner, 1970;Arbab & Turner, 1971), in contrast to drugs lacking intrinsic activity (propranolol, sotalol and Ro 3-3528) (Kofi Ekue, Lowe & Shanks, 1970;Phillips, Turner, Houghton & Ferriman, 1973).…”

Ro 3–4787, A NEW β‐ADRENOCEPTOR BLOCKING AGENT: STUDIES IN NORMAL VOLUNTEERS

“…Hill & Turner (1968) studied the effects of Ro 3-3528 on the heart rate during rest, after administration of isoprenaline and during exercise. Phillips, Turner, Houghton & Ferriman (1973) found that this drug was similar to propranolol in controlling hyperthyroid tachycardia. In animal studies, Ro 34787 differed from the earlier drug in possessing greater potency, a longer duration of action and some degree of intrinsic sympathomimetic activity, being approximately one-quarter as active in this respect as practolol (Parkes & Parks, 1971, personal …”