A comparison of the effects of captopril and flosequinan in patients with severe heart failure.

Angiotensin converting enzyme inhibitors have greatly improved the treatment of patients with chronic heart failure but they are not effective in all patients, and their use may be limited by side effects. There is, therefore, a need to investigate new drugs and to compare their efficacy with angiotensin converting enzyme inhibitors. Flosequinan is a new direct-acting vasodilator that has been shown to be effective in placebo-controlled studies. Patients with chronic heart failure in NYHA classes II or III who remained symptomatic despite at least 80 mg of frusemide daily were recruited from two centers. Following a single-blind placebo run-in period, the patients were randomized double blind to either the addition of captopril or flosequinan for 6 weeks. Following a further 2-week placebo washout period, they were then given the alternative treatment. Symptom-limited treadmill exercise times, scores of perceived exertion, and corridor walk tests were measured at two weekly intervals during the study. Twenty-five patients entered the study, 16 of whom completed without a change in diuretic dose. Five patients were withdrawn while taking captopril and two while taking flosequinan; two were withdrawn during the placebo washout period. For those patients who completed the study, flosequinan increased treadmill exercise tolerance from a mean (SEM) placebo time of 11.5 (1.0) minutes by 2.4 (0.6) (p = 0.0002) and captopril from 12.0 (0.8) minutes by 1.2 (0.6) minutes (p = 0.08). Comparison of the other measures of efficacy revealed no difference between the groups. In this short-term study flosequinan appeared to be equal in efficacy to captopril.