Combined hemodynamic and scintigraphic assessment of piroximone (MDL 19,205) and comparison with dobutamine and...

The acute hemodynamic responses to intravenous infusion of piroximone (MDL 19,205), a nonglycoside, noncatecholamine agent with positive inotropic activity in vitro, were compared with those of intravenous dobutamine and sodium nitroprusside, respectively, in 2 groups of patients with New York Heart Association class III or IV symptoms. Each drug was titrated to optimal dosage (dobutamine, 12.5 +/- 3.9 micrograms/kg/min; nitroprusside, 2.5 +/- 0.6 micrograms/kg/min; piroximone 1.4 +/- 0.6 mg/kg) and simultaneous hemodynamic and scintigraphic values were measured. In group 1, the increase in cardiac index was slightly greater with piroximone than with dobutamine (from 1.6 +/- 0.5 to 2.7 +/- 0.6 vs 2.4 +/- 0.6 liters/min/m2, p less than 0.025) and only piroximone significantly decreased left ventricular (LV) filling pressure (from 29 +/- 7 to 22 +/- 8 mm Hg, p less than 0.05). Both agents increased heart rate and systolic blood pressure. In group 2, cardiac index increased similarly with nitroprusside and piroximone (1.5 +/- 0.6 to 2.6 +/- 0.8 and 1.6 +/- 0.5 to 2.6 +/- 0.5 liters/min/m2, difference not significant), whereas LV filling pressure decreased slightly less with piroximone (29 +/- 7 to 24 +/- 10 vs 30 +/- 7 to 20 +/- 11 mm Hg, difference not significant). Only nitroprusside reduced mean arterial pressure (88 +/- 13 to 72 +/- 12 mm Hg, p less than 0.001 between drugs). In group 1, systolic blood pressure to end-systolic volume ratio increased in 9 of 10 patients taking both piroximone and dobutamine, whereas in group 2, this ratio increased in 7 of 8 patients taking piroximone and declined in 7 of 8 taking nitroprusside.(ABSTRACT TRUNCATED AT 250 WORDS)