Felodipine

Felodipine is a dihydropyridine-type calcium channel blocker with particularly high vascular selectivity. It acts preferentially on the smooth muscle cells of the arteries and has comparatively little effect on the heart.

Felodipine is taken as an extended-release tablet that releases the active ingredient evenly over 24 hours. It is approved for the treatment of high blood pressure and stable angina pectoris. Well-known products are Felodipin-ratiopharm® and Plendil®.

The high vascular selectivity means that felodipine strongly dilates the blood vessels but has hardly any effect on heart function. This is advantageous but can lead to a reflex increase in heart rate.

Felodipine blocks L-type calcium channels with high vascular selectivity:

Mechanism of action:

• Selective blockade of the calcium channels in the vascular muscle
• Very high vascular/cardiac selectivity (approx. 100:1)
• Arterial vasodilation and blood pressure reduction
• Reduction of peripheral vascular resistance

Special features:

• Highest vascular selectivity of all dihydropyridines
• Hardly any negative inotropy (no reduction in the heart's force of contraction)
• As an extended-release form, an even 24-hour effect
• Less reflex tachycardia than with short-acting calcium channel blockers

Additional effect:

• Natriuretic effect (promotes salt excretion)
• Improves kidney perfusion
• May increase renal sodium excretion

Onset of action: Extended-release form: onset of action after 2-5 hours. Even effect over 24 hours.

Felodipine is suitable for:

• Adults with high blood pressure
• Chronic stable angina pectoris

Particularly suitable for:

• High blood pressure with a normal heart rate
• Older patients with isolated systolic hypertension
• In combination with beta blockers (complementary mechanism)
• Patients with mild kidney impairment

Not suitable:

• Decompensated heart failure
• Unstable angina pectoris
• Severe aortic stenosis
• Pregnancy and breastfeeding
• Within 4 weeks after an acute heart attack

High blood pressure:

• Starting dose: 5 mg once daily
• Usual dose: 5-10 mg once daily
• Maximum dose: 10 mg daily

Angina pectoris:

• 5-10 mg once daily

Older patients / liver impairment:

• Starting dose: 2.5 mg once daily

Available strengths:

• 2.5 mg, 5 mg, 10 mg extended-release tablets

How to take:

• Once daily, preferably in the morning
• Swallow the extended-release tablet whole without chewing – do not split, chew, or crush it
• Can be taken with or without a light meal
• Do NOT take with grapefruit juice

Important notes:

• Do not split extended-release tablets (the extended-release mechanism is destroyed)
• Grapefruit juice can increase levels 2-3-fold
• Regular blood pressure monitoring
• If flushing and headaches occur at the start: often improvement after 1-2 weeks

Felodipine must not be taken in case of:

• Hypersensitivity to felodipine or other dihydropyridines
• Decompensated heart failure
• Severe aortic stenosis
• Unstable angina pectoris
• Acute heart attack (first 4 weeks)
• Pregnancy and breastfeeding

Caution in case of:

• Liver impairment (delayed breakdown – lower dose)
• Tachycardia (reflex increase in heart rate possible)
• Severe kidney impairment

Pregnancy: Contraindicated. Animal studies have shown evidence of harm to the unborn child.

Very common (10% or more):

• Ankle edema (dose-dependent)

Common (1-10%):

• Headache
• Facial redness (flushing)
• Dizziness

Uncommon (0.1-1%):

• Palpitations, tachycardia
• Fatigue
• Gastrointestinal complaints
• Skin rash

Rare:

• Joint pain
• Muscle pain
• Paresthesia (tingling)
• Elevated liver enzymes
• Sensitivity of the skin to light

Very rare:

• Overgrowth of the gums (gingival hyperplasia)

Note: Flushing and headaches occur especially at the start of therapy and usually improve after 1-2 weeks. The extended-release form reduces these side effects compared with fast-release calcium channel blockers.

Strong interaction with grapefruit:

• Grapefruit juice inhibits CYP3A4 in the intestine
• Can increase felodipine levels 2-3-fold
• Strictly avoid grapefruit juice and grapefruit!

Caution with:

• CYP3A4 inhibitors (erythromycin, itraconazole, ketoconazole) → increased levels
• CYP3A4 inducers (rifampin, phenytoin, carbamazepine, St. John's wort) → reduced effect
• Other blood pressure-lowering drugs → increased hypotension
• Cimetidine → increased felodipine levels
• Tacrolimus → increased tacrolimus levels

Combines well with:

• Beta blockers (complementary mechanism, reflex tachycardia is prevented)
• ACE inhibitors and sartans