HIGH-DOSE NITRATES IN THE IMMEDIATE MANAGEMENT OF UNSTABLE ANGINA - OPTIMAL DOSAGE, ROUTE OF ADMINISTRATION, AND THERAPEUTIC GOALS

Nitrates are commonly used for rapid relief of ischemia in the initial management of unstable angina, However, their optimal dosage, route o f administration, and therapeutic goals have not been fully establishe d, This study was conducted to determine the optimal dosage and mode o f administration (intravenous bolus versus sublingual spray) of nitrat es and the therapeutic goals of their use in the immediate management of unstable angina, In a single center prospective trial, 72 consecuti ve patients with unstable angina accompanied by typical ST-segment dep ression on electrocardiogram were randomly assigned to receive isosorb ide dinitrate either as repeated intravenous boluses or as sublingual sprays while being delivered to the hospital by a mobile intensive car e unit, Optimal nitrate dosage was tailored to pain relief while monit oring mean blood pressure reduction to an optimal range (5% to 20%) wi thout dosage restriction. The mean nitrate dosage needed for ischemia control during the first hour of treatment was 7.8 +/- 3.8 mg, Optimal blood pressure reduction was achieved by significantly more intraveno usly treated patients than sublingually treated patients (68% v 41%, P = .037), Intrave nously treated patients also experienced a more pron ounced therapeutic effect, as assessed by reduction in chest pain scor e (67% v 39%, P = .0004) and decrease in ST-segment depressions (57% v 27%, P = .004). These results show that higher doses of nitrates than previously recommended are required for ischemia control during the i nitial management of unstable angina, The use of repeated intravenous boluses is safe and more easily controlled and, therefore, more effica cious than sublingual sprays in inducing the maximal anti ischemic eff ect while avoiding significant hypotension. Copyright (C) 1998 by W.B. Saunders Company.