Pharmacotherapeutic group: calcium channel blockers, dihydropyridine derivatives; ATC code: C08CA02.
Mechanism of action
Felodipine is a vascular selective calcium antagonist, which lowers arterial blood pressure by decreasing systemic vascular resistance. Due to the high degree of selectivity for smooth muscle in the arterioles, felodipine in therapeutic doses has no direct effect on cardiac contractility or conduction. Because there is no effect on venous smooth muscle or adrenergic vasomotor control, felodipine is not associated with orthostatic hypotension.
Felodipine possesses a mild natriuretic/diuretic effect and fluid retention does not occur.
Pharmacodynamic effects
Felodipine is effective in all grades of hypertension. It can be used as monotherapy or in combination with other antihypertensive medicinal products, e.g. ß-adrenoceptor blockers, diuretics or ACE-inhibitors, in order to achieve an increased antihypertensive effect. Felodipine reduces both systolic and diastolic blood pressure and can be used in isolated systolic hypertension.
Felodipine has anti-anginal and anti-ischaemic effects due to improved myocardial oxygen supply/demand balance. Coronary vascular resistance is decreased and coronary blood flow and myocardial oxygen supply are increased by felodipine due to dilatation of both epicardial arteries and arterioles. The reduction in systemic blood pressure caused by felodipine leads to decreased left ventricular afterload and myocardial oxygen demand.
Felodipine improves exercise tolerance and reduces anginal attacks in patients with stable effort-induced angina pectoris. Felodipine can be used as monotherapy or in combination with β-adrenoceptor blockers in patients with stable angina pectoris.
Haemodynamic effects
The primary haemodynamic effect of felodipine is a reduction of total peripheral vascular resistance, which leads to a decrease in blood pressure. These effects are dose-dependent. Generally, a reduction in blood pressure is evident two hours after the first oral dose and lasts for at least 24 hours and the trough/peak ratio is usually well above 50%.
Plasma concentrations of felodipine are positively correlated to the decrease in total peripheral resistance and blood pressure.
Cardiac effects
Felodipine in therapeutic doses has no effect on cardiac contractility or atrioventricular conduction or refractoriness.
Antihypertensive treatment with felodipine is associated with significant regression of pre-existing left ventricular hypertrophy.
Renal effects
Felodipine has a natriuretic and diuretic effect due to reduced tubular reabsorption of filtered sodium. Felodipine does not affect daily potassium excretion. The renal vascular resistance is decreased by felodipine. Felodipine does not influence urinary albumin excretion.
In cyclosporin-treated renal transplant recipients, felodipine reduces blood pressure and improves both the renal blood flow and the glomerular filtration rate. Felodipine may also improve early renal graft function.
Clinical efficacy
In the HOT (Hypertension Optimal Treatment) study, the effect on major cardiovascular events (i.e. acute myocardial infarction, stroke and cardiovascular death) was studied in relation to diastolic blood pressure targets ≤90 mmHg, ≤85 mmHg and ≤80 mmHg and achieved blood pressure, with felodipine as baseline therapy.
A total of 18,790 hypertensive patients (DBP 100-115 mmHg), aged 50-80 years were followed for a mean period of 3.8 years (range 3.3-4.9). Felodipine was given as monotherapy or in combination with a betablocker, and/or an ACE- inhibitor and/or a diuretic. The study showed benefits of lowering SBP and DBP down to 139 and 83 mmHg, respectively.
According to the STOP-2 (Swedish Trial in Old Patients with Hypertension-2 study), performed in 6614 patients, aged 70-84 years, dihydropyridine calcium antagonists (felodipine and isradipine) have shown the same preventive effect on cardiovascular mortality and morbidity as other commonly used classes of antihypertensive medicinal products – ACE inhibitors, beta-blockers and diuretics.
Paediatric population
There is limited clinical trial experience of the use of felodipine in hypertensive paediatric patients. In a randomised, double-blind, 3-week, parallel group study in children aged 6-16 years with primary hypertension, the antihypertensive effects of once daily felodipine 2.5 mg (n=33), 5 mg (n=33) and 10 mg (n=31) were compared with placebo (n=35). The study failed to demonstrate the efficacy of felodipine in lowering blood pressure in children aged 6-16 years (see section 4.2).
The long-term effects of felodipine on growth, puberty and general development have not been studied. The long-term efficacy of antihypertensive therapy as therapy in childhood to reduce cardiovascular morbidity and mortality in adulthood has also not been established.