Brands, Medical Use, Clinical Data
- Adrenergic beta-receptor agonists
- Cardiotonic Agents
Brands / Synonyms
Used to elicit acute cardiovascular responses, similar to those produced by exercise, in order to aid in diagnosing the presence or absence of coronary artery disease (CAD) in patients who cannot exercise adequately.
Mechanism of Action
Arbutamine is a synthetic catecholamine with positive chronotropic and inotropic properties. The chronotropic (increase in heart rate) and inotropic (increase in force of contraction) effects of arbutamine serve to mimic exercise by increasing cardiac work (producing stress) and provoke myocardial ischemia in patients with compromised coronary arteries. The increase in heart rate caused by arbutamine is thought to limit regional subendocardial perfusion, thereby limiting tissue oxygenation. In functional assays, arbutamine is more selective for beta-adrenergic receptors than for alpha-adrenergic receptors. The beta-agonist activity of arbutamine provides cardiac stress by increasing heart rate, cardiac contractility, and systolic blood pressure. The degree of hypotension that occurs for a given chronotropic activity is less with arbutamine than, for example, with isoproterenol because alpha receptor activity is retained.
Biotrnasformation / Drug Metabolism
Primarily metabolized to methoxyarbutamine. Another possible metabolite is ketoarbutamine. The metabolites of arbutamine appear to have less pharmacological activity and a longer half-life and than the parental drug.
Beta-adrenergic blocking agents: concurrent use may blunt the response to arbutamine. Beta-adrenergic blocking agents should be withdrawn at least 48 hours before conducting an arbutamine-mediated stress test. Antiarrhythmic agents, class I (such as flecainide, lidocaine, or quinidine): concurrent use with arbutamine may have a proarrhythmic effect. Antidepressants (tricyclic), atropine or other anticholinergic agents, or digitalis glycosides: concurrent use with arbutamine may produce additive inotropic and/or chronotropic effects.