Felodipine

 Action Inhibits movement of calcium ions across cell membrane in systemic and coronary vascular smooth muscle, altering contractile process.

 Indications Treatment of hypertension.

 Contraindications Sick sinus syndrome; second- or third-degree AV block except with functioning pacemaker; hypotension with systolic pressure < 90 mm Hg.

 Route/Dosage

PO 2.5 to 10 mg once daily. Maximum 20 mg once daily. Elderly rarely require > 10 mg qd.

 Interactions

Barbiturates: Effects of felodipine may be decreased. Carbamazepine: Plasma levels of felodipine may be decreased, reducing effect. Food: Effects of felodipine may increase if given with grapefruit juice. Histamine H2 antagonists: Cimetidine may increase effects of felodipine. Hydantoins: Serum felodipine levels may be decreased, reducing effects. Other antihypertensive agents: May have additive effects.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Peripheral edema; hypotension; syncope; AV block; MI; arrhythmias; angina; tachycardia. CNS: Headache; dizziness; lightheadedness; nervousness; psychiatric disturbances; paresthesias; somnolence; asthenia; insomnia; anxiety; irritability. GI: Nausea; diarrhea; constipation; abdominal discomfort; cramps; dyspepsia; vomiting; dry mouth; thirst; flatulence. GU: Micturition disorders; sexual difficulties. HEMA: Epistaxis. RESP: Nasal or chest congestion; sinusitis; rhinitis; pharyngitis; shortness of breath; wheezing; cough; sneezing; respiratory infections. OTHER: Muscle cramps, pain, or inflammation; gingival hyperplasia.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. Children: Safety and efficacy not established. Elderly patients: May have greater hypotensive effects and increased risk of peripheral edema when dosage exceeds 20 mg/day. Monitor closely; doses > 10 mg usually not needed. CHF: Use with caution. Hepatic impairment: Use with caution in patients with impaired hepatic function or reduced hepatic blood flow. Withdrawal syndrome: Abrupt withdrawal may cause increased frequency and duration of angina. Taper dose gradually.

 Administration/Storage

• Do not crush tablet or allow patient to chew it.
• Give with food if patient experiences GI upset.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies.
• Monitor BP frequently during dosage adjustment, especially for patients > 65 yr and patients with liver dysfunction.

 Patient/Family Education

• Instruct patient not to crush or chew tablets.
• Teach patient and family member correct method of measuring BP.
• Explain that mild peripheral edema may occur within 2 to 3 wk after beginning therapy.
• Advise patient that drug may cause drowsiness and dizziness. Use caution while driving or performing other tasks requiring mental alertness.
• Instruct patient to avoid sudden position changes to prevent postural hypotension.
• Explain importance of proper oral hygiene and regular dental examinations to prevent gum disease.
• Tell patient not to double up medication if dose is missed, but to wait and take next scheduled dose on time.
• Instruct patient to report the following symptoms to physician: Irregular heart beat, increased frequency or severity of angina, shortness of breath, swelling of hands and feet, dizziness, constipation, nausea, unusual bleeding or bruising, and hypotension.