No

Calcium Channel Blocker

Treatment of hypertension, congestive heart failure

C

Hypersensitivity to felodipine, any component, or other calcium channel blocker

Watch for hypotension and syncope (can rarely occur). Reflex tachycardia may occur. Use caution in patients with heart failure particularly with concurrent beta-blocker use. Elderly patients and patients with hepatic impairment should start off with a lower dose. Peripheral edema is the most common side effect (occurs within 2-3 weeks of starting therapy). Safety and efficacy in children have not been established. Dosage titration should occur after 14 days on a given dose.

2% to 10%:

Cardiovascular: Peripheral edema (2% to 17%), tachycardia (0.4% to 2.5%), flushing (4% to 7%)

Central nervous system: Headache (11% to 15%)

Gastrointestinal: Gingival hyperplasia

0.5% to 1.5%

<1% (Limited to important or life-threatening symptoms): Chest pain, facial edema, flu-like illness, myocardial infarction, hypotension, syncope, angina pectoris, arrhythmia, premature beats, abdominal pain, diarrhea, vomiting, dry mouth, flatulence, acid, MI, CVA, CHF, regurgitation, gynecomastia, anemia, arthralgia, back pain, leg pain, foot pain, muscle cramps, myalgia, arm pain, knee pain, hip pain, insomnia, depression, anxiety disorders, irritability, nervousness, somnolence, decreased libido, dyspnea, pharyngitis, bronchitis, influenza, sinusitis, epistaxis, respiratory infection, contusion, erythema, urticaria, visual disturbances, impotence, urinary frequency, urinary urgency, dysuria, polyuria, gingival hyperplasia, flushing, palpitations, nausea, constipation, dizziness, paresthesias

The primary cardiac symptoms of calcium blocker overdose include hypotension and bradycardia. The hypotension is caused by peripheral vasodilation, myocardial depression, and bradycardia. Bradycardia results from sinus bradycardia, second- or third-degree atrioventricular block, or sinus arrest with junctional rhythm. Intraventricular conduction is usually not affected so QRS duration is normal (verapamil does prolong the P-R interval and bepridil prolongs the Q-T and may cause ventricular arrhythmias, including torsade de pointes).

In a few reported cases, overdose with calcium channel blockers has been associated with hypotension and bradycardia, initially refractory to atropine but becoming more responsive to this agent when larger doses (approaching 1 g/hour for more than 24 hours) of calcium chloride was administered.

CYP3A3/4 enzyme substrate

Beta-blockers may have increased pharmacokinetic or pharmacodynamic interactions with felodipine.

Calcium may reduce the calcium channel blocker's effects, particularly hypotension.

Carbamazepine significantly reduces felodipine's bioavailability; avoid this combination.

Cimetidine may inhibit felodipine metabolism (AUC increased 50%); use caution

Cyclosporine increases felodipine's serum concentration; avoid the combination or reduce dose of felodipine and monitor blood pressure.

Ethanol increases felodipine's absorption; watch for a greater hypotensive effect.

Erythromycin decreases felodipine's metabolism; monitor blood pressure.

Grapefruit juice increases the bioavailability of felodipine; monitor for altered felodipine effects.

Nafcillin decreases plasma concentration of felodipine; avoid this combination.

Rifampin increases the metabolism of the calcium channel blocker; adjust the dose of the calcium channel blocker to maintain efficacy.

Inhibits calcium ions from entering the "slow channels" or select voltage-sensitive areas of vascular smooth muscle and myocardium during depolarization, producing a relaxation of coronary vascular smooth muscle and coronary vasodilation; increases myocardial oxygen delivery in patients with vasospastic angina

Onset of effect: 2-5 hours

Duration: 16-24 hours

Absorption: 100%; absolute: 20% due to first-pass effect

Protein binding: >99%

Metabolism: >99% in liver

Half-life: 11-16 hours

Elimination: In urine as metabolites

Adults: Oral: 2.5-10 mg once daily; usual initial dose: 5 mg; increase by 5 mg at 2-week intervals, as needed; maximum: 10 mg

Elderly: Begin with 2.5 mg/day

Dosing adjustment/comments in hepatic impairment: Begin with 2.5 mg/day; do not use doses >10 mg/day

Should be taken without food; the bioavailability of felodipine is influenced by the presence of food and has been shown to increase more than twofold when taken with concentrated grapefruit juice

Felodipine alone or in combination with other agents is effective in the management of hypertension and angina. Felodipine has neutral effects on cardiovascular morbidity and mortality in patients with heart failure and thus is safe to use to treat hypertension and/or angina in this setting.

May cause dizziness; rarely may cause nervousness, insomnia, or depression

Carbamazepine may decrease felodipine effect

No information available to require special precautions

Calcium channel blockers cause gingival hyperplasia in approximately 1% of patients. There have been fewer reports with felodipine than with other CCBs. The hyperplasia will disappear with cessation of drug therapy. Consultation with physician is suggested.

Take without food. Take as prescribed; do not stop abruptly without consulting prescriber immediately. Swallow whole; do not crush or chew. You may experience headache (if unrelieved, consult prescriber), nausea or vomiting (frequent small meals may help), constipation (increased dietary bulk and fluids may help), depression (should resolve when drug is discontinued). May cause dizziness or drowsiness; use caution when driving or engaging in tasks that require alertness until response to drug is known. Report any chest pain or swelling of hands or feet, respiratory distress, sudden weight gain, or unresolved constipation. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to be pregnant. Consult prescriber if breast-feeding.

Do not crush extended release tablets

Tablet, extended release: 2.5 mg, 5 mg, 10 mg

Buur T, Larsson R, Regardh CG, et al, "Pharmacokinetics of Felodipine in Chronic Hemodialysis Patients," J Clin Pharmacol, 1991, 31(8):709-13.

Neuvonen PJ and Suhonen R, "Itraconazole Interacts With Felodipine," J Am Acad Dermatol, 1995, 33(1):134-5.

Todd PA and Faulds D, "Felodipine. A Review of the Pharmacology and Therapeutic Use of the Extended Release Formulation in Cardiovascular Disorders," Drugs, 1992, 44(2):251-77.

Wade JR and Sambol NC, "Felodipine Population Dose-Response and Concentration-Response Relationships in Patients With Essential Hypertension," Clin Pharmacol Ther, 1995, 57(5):569-81.