Dose-related haemodynamic effects and pharmacokinetics of oral nicorandil in patients evaluated for chest pain.

We studied the acute haemodynamic dose response of nicorandil, a combined nitrate and potassium channel opener, in patients evaluated for chest pain. Single dose oral nicorandil (5, 10, 20, or 30 mg) or placebo was given to 42 right-heart catheterized patients using a randomized block design. Persistent, significant (P < 0.05) haemodynamic changes occurred primarily after 30 mg. Arterial systolic pressure fell significantly after all doses and remained reduced (maximum, 31 mmHg) up to 6 h after 30 mg; heart rate increased significantly up to 1 h. Individual haemodynamic sensitivity varied and three patients (1, 10 mg; 2, 30 mg) developed transient symptomatic hypotension associated with bradycardia. Pulmonary artery systolic pressure (diastolic was unchanged) declined significantly (maximum, 5 mmHg) up to 6 h after 30 mg whereas pulmonary capillary wedge (baseline normal) and mean right atrial pressures decreased transiently. Cardiac index (baseline normal) declined slightly (significantly after 30 mg); however, stroke volume index and stroke work index were significantly and persistently reduced after all doses. Total systemic vascular resistance declined slightly after 30 mg. Individual plasma nicorandil concentrations were variable and systemic bioavailability was reduced compared with values reported in healthy subjects. Nicorandil demonstrated cardiac unloading actions. Variable plasma concentrations, haemodynamic effects, and patient sensitivity warrant low initial doses with individual dose titration, especially if cardiac filling pressures are low.