Effects of ibopamine on heart performance: a radionuclide ventriculography study in patients with idiopathic dilatative cardiomyopathy.

The effects of ibopamine (SB-7505, Ib), a new orally active 3,4-diisobutyryl ester of N-methyldopamine, were studied in 8 patients aged between 34-56 years with idiopathic dilatative cardiomyopathy (II-III New York Heart Association Class) diagnosed by means of right and left heart catheterization and selective coronary angiography. Equilibrium radionuclide ventriculography (RVG) was performed in baseline conditions and 1, 2, and 3 h after the administration of a single oral dose of 200-300 mg of Ib. After 2 h Ib increased cardiac output (CO) (+16%, p less than 0.05), stroke volume (SV) (+12%, p less than 0.05) and ejection fraction (EF) (+10%, p less than 0.01). Patients were then randomly treated with placebo or Ib 100 mg t.i.d. according to a double-blind cross-over design for two periods of 15 days each. At the end of each period a RVG was repeated in baseline conditions and 1, 2, and 3 h thereafter. The mean values of the four determinations where higher after Ib than after placebo (CO: +10.1%, p less than 0.01; SV: +14.1%, p less than 0.01; EF: +10.8%, p less than 0.05). Patients subsequently started a long-term treatment with Ib 100 mg t.i.d.; after 6 months patients underwent RVG 3 h after the last dose of Ib: compared with the values recorded at the same time after the short-term treatment. CO further increased by 17% (NS), SV by 22% (p less than 0.05) and EF by 24% (p less than 0.05). The treatment was well tolerated.(ABSTRACT TRUNCATED AT 250 WORDS)