Double-blind, placebo-controlled study of the efficacy of flosequinan in patients with chronic heart failure

Objectives. The aim of this study was to assess the efficacy of flosequinan in chronic heart failure. Background. Flosequinan is a new vasodilator drug that acts by interfering with the inositol-triphosphate/protein kinase C pathway, an important mechanism of vasoconstriction. The drug dilates both peripheral arteries and veins, is orally active and has a long duration of action that permits once-daily dosing. Previous studies have shown that flosequinan produces sustained hemodynamic benefits in heart failure, but large scale studies evaluating its clinical efficacy have not been reported. Methods. One hundred ninety-three patients with chronic heart failure (New York Heart Association functional class II or III and left ventricular ejection fraction <40%) receiving digoxin and diuretic drugs were randomly assigned (double-blind) to the addition of flosequinan (100 mg once daily, n = 93) or placebo (n = 100) for 3 months. The clinical status and exercise tolerance of each patient was evaluated at the start of the study and every 2 to 4 weeks during the trial while background therapy remained constant. Results. After 12 weeks, maximal treadmill exercise time increased by 96 s in the flosequinan group but by only 47 s in the placebo group (p = 0.022 for the difference between groups). Maximal oxygen consumption increased by 1.7 ml/kg per in the flosequinan group (n = 17) but by only 0.6 ml/kg per min in the placebo group (n = 23), p = 0.05 between the groups. Symptomatically, 55% of patients receiving flosequinan but only 36% of patients receiving placebo benefited from treatment (p = 0.018). In addition, fewer patients treate with flosequinan had sufficiently severe worsening of heart failure to require a change in medication or withdrawal from the study (p = 0.07). By intention to treat, seven patients in the flosequinan group and two patients in the placebo group died. Conclusions. These findings indicate that flosequinan is an effective drug for patients with chronic heart failure who remain symptomatic despite treatment with digoxin and diuretic drugs. The effect of the drug on survival remains to be determined.