Haemodynamic effects of a new vasodilator drug, felodipine, in healthy subjects.

The haemodynamic effects of a new vasodilating drug, felodipine, were studied in eight, healthy, male subjects, aged 22-31 years. The drug was given as an oral solution in the dose of 0.15 mg/kg. Thirty-five minutes later further dose of 0.15 mg/kg was administered. Felodipine induced a pronounced decrease in diastolic blood pressure (maximal effect 15 +/- 4 mm Hg) and in the systemic vascular resistance. Cardiac output increased (maximum by 4.2 +/- 0.31/min), due to an increase both in the stroke volume and the heart rate. The maximal increase in the stroke volume (measured from echo cardiograms) and the heart rate were 33 +/- 5 ml and 23 +/- 3 beats/min, respectively. Felodipine caused a significant decrease in the pre-ejection period (23 +/- 3 ms) and an increase in the left ventricular ejection time (29 +/- 3 ms). The quotient PEP/LVET fell from 0.36 +/- 0.01 to 0.28 +/- 0.01. Significant activity of felodipine could be recorded at a plasma level of about 15 nmol/l. When the maximal haemodynamic effects were recorded the plasma level was about 40 nmol/l. After a cumulative dose of 0.30 mg/kg, there was a twofold variation in the maximal plasma level (from 31 to 61 nmol/l). The results of the present investigation are in agreement with previous haemodynamic studies in animals. It would appear that felodipine is a potent arteriolar vasodilator and it might well be of considerable value in the management of patients with hypertension or congestive cardiac failure.