Denopamine, a selective beta1-receptor agonist and a new coronary vasodilator.

Up until now, it has been suggested that nitrate and/or calcium channel blockers were effective against variant angina pectoris. On the other hand, it is known that about 20% of variant angina pectoris was refractory to both nitrate and calcium channel blockers. In Japan, it has been reported that denopamine, which is an oral beta1-adrenoceptor selective agonist developed by the Japanese pharmaceutical industry (Tanabe Seiyaku), is effective in those refractory cases. To date, in Japan nine cases have been recognized of patients with vasospastic angina pectoris whose symptoms were relieved by taking denopamine, including one case in which the author has had personal experience. Eight of these nine cases were refractory, and were not relieved by combined therapy using both nitrate and a calcium channel blocker. It was also documented that denopamine was effective in cases where attacks were not relieved by prazosin or magnesium, which have been documented as effective in other refractory cases. In a study of canine coronary arteries, localization of beta-adrenoceptor subtypes was documented, with the beta1-adrenoceptor predominantly found in the conduit coronary artery. In recent years it has been emphasized that the principal role of sympathetic nerves was not associated with the constrictive action of alpha-adrenoceptors, but with the coronary dilative action of beta-adrenoceptors. It would therefore be worthwhile to determine whether denopamine is able to relieve vasospastic angina pectoris in many more cases.