Home Drug Guide Nifedipine

Drug Guide

Generic Name

Nifedipine

Brand Names Procardia, Adalat, Procardia XL, Adalat Cc, Afeditab CR

Classification

Therapeutic: Antihypertensive, Antianginal

Pharmacological: Calcium Channel Blocker

FDA Approved Indications

Hypertension
Chronic Stable Angina
Vasospastic Angina (Prinzmetal's Angina)

Mechanism of Action

Nifedipine inhibits the influx of calcium ions into vascular smooth muscle and cardiac muscle by blocking L-type calcium channels, resulting in vasodilation and decreased peripheral resistance.

Dosage and Administration

Adult: Initially, 30-60 mg once daily; titrate as needed up to 90-120 mg daily, administered once or in divided doses.

Pediatric: Not typically recommended for pediatric use; consult specific guidelines.

Geriatric: Start at lower doses due to increased sensitivity and risk of hypotension.

Renal Impairment: Use cautiously; monitor blood pressure and symptoms.

Hepatic Impairment: Use with caution; dose adjustments may be necessary.

Pharmacokinetics

Absorption: Well absorbed; extended-release formulations provide gradual absorption.

Distribution: Widely distributed; crosses the placenta and enters breast milk.

Metabolism: Extensively metabolized in the liver via CYP3A4.

Excretion: Primarily via feces, with some renal excretion.

Half Life: Approximately 2-4 hours for immediate-release; longer for extended-release formulations.

Contraindications

Hypersensitivity to nifedipine or other dihydropyridines.
Acute myocardial infarction with cardiogenic shock.

Precautions

Severe aortic stenosis, heart failure, hypotension, unstable angina. Use cautiously in patients with liver impairment; monitor for signs of hypotension and reflex tachycardia.

Adverse Reactions - Common

Headache (Common)
Dizziness (Common)
Peripheral edema (Common)
Flushing (Common)

Adverse Reactions - Serious

Hypotension (Serious)
Reflex tachycardia (Serious)
Arrhythmias (Serious)
Allergic reactions (Rare)

Drug-Drug Interactions

CYP3A4 inhibitors (e.g., ketoconazole, erythromycin) increase nifedipine levels.
Other antihypertensives may have additive effects.

Drug-Food Interactions

Grapefruit juice can increase nifedipine levels.

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor blood pressure, heart rate, signs of edema, and liver function.

Diagnoses:

Risk for hypotension
Ineffective tissue perfusion

Implementation: Administer as prescribed; monitor for adverse effects; educate patient on symptoms of hypotension.

Evaluation: Assess blood pressure response and symptom relief.

Patient/Family Teaching

Take medication exactly as prescribed.
Do not suddenly stop medication.
Monitor for signs of swelling, dizziness, or irregular heartbeat.
Avoid grapefruit juice while on this medication.

Special Considerations

Black Box Warnings:

Use with caution in patients with severe aortic stenosis due to risk of worsening cardiac function.

Genetic Factors: Metabolized by CYP3A4; genetic variations may affect levels.

Lab Test Interference: May cause false low BP readings with certain cuff sizes or devices.

Overdose Management

Signs/Symptoms: Severe hypotension, bradycardia, reflex tachycardia, dizziness, fainting.

Treatment: Discontinue nifedipine; supportively manage blood pressure with IV fluids or vasopressors as needed; activated charcoal may be considered if ingestion was recent.

Storage and Handling

Storage: Store at room temperature, 20-25°C (68-77°F).

Stability: Stable under proper storage conditions.