Effect of Felodipine on Arterial Blood Flow and Venous Function at Rest in Patients with Mild Essential Hypertension

Felodipine is a second-generation dihydropyridine calcium antagonist used to treat mild to moderate arterial hypertension. The authors used venous occlusion plethysmography to study the effect of this drug on lower limb arterial inflow and venous outflow in 10 at rest patients with mild essential hypertension. They also sought correlations between changes in district blood flow and blood pressure. Plethysmography was carried out at 8 AM and 4, 8, and 24 hours later at baseline (after washout), on the first day of treatment with a single daily administration of 10 mg felodipine ER, and after 7 and 30 days of treatment. The drug was given after the 8 AM evaluation. The authors determined rest flow, maximal venous incremental volume (MVIV) at 40 mmHg and 60 mmHg, and gradient of venous volume between 60 and 40 mmHg divided by the pressure difference (DV/DP) as index of venous distensibility. On the days of plethysmographic evaluation, arterial blood pressure and heart rate were measured continuously over 24 hours by the ABPM (Ambulatory Blood Pressure Monitoring). The results were analyzed by ANOVA. Rest flow, MVIV, and DV/DP were stable at the baseline evaluation. On days 1, 7, and 30 of treatment the rest flow after 4 and 8 hours was significantly greater than at 8 AM but had always returned to normal after 24 hours. No other plethysmographic parame ters changed significantly; in particular venous outflow remained unchanged. Mean arterial, systolic, and diastolic blood pressure were significantly reduced, compared with baseline, following treatment on the first day and after 7 and 30 days' treatment. There was no effect on heart rate. The authors conclude that felodipine is useful for the treatment of mild essential hypertension, since it reduces arterial resistance without altering venous capacitance or distensibility.