Effects of prenalterol administered orally in patients with congestive heart failure

A single-blind study of prenalterol 20-200 mg daily in a slow-release tablet preparation and a placebo was performed in 15 patients with moderate to severe congestive heart failure (NYHA II-IV) to evaluate the haemodynamic and clinical effects of oral prenalterol. Non-invasive parameters in the measurement of cardiac output, stroke volume, pre-ejection period index (PEPI), PEP/LVET ratio, ejection fraction and mean Vcf were significantly improved, indicating beneficial effects of prenalterol on cardiac contractility. Systolic blood pressure, heart rate and rate-pressure product were slightly increased at rest but were considerably lower during exercise. Arrhythmogenecity was not seen in the patients studied. Subjective improvement was noted in the majority of patients as evidenced by a decreased frequency of dyspnoea, fatigue and angina. Unwanted effects, such as palpitations and transmitted arm pulsations, were transient and disappeared with dose adjustment, while the inotropic effect of the medication was maintained. The clinical response appeared to be sustained for up to 2 weeks of treatment, indicating non-development of tachyphylaxis.