Nifedipine — NZ Medication Guide

What is Nifedipine?

Nifedipine (generic name: nifedipine) is a medication used primarily for hypertension, angina, and Raynaud’s phenomenon. Nifedipine modified-release tablets (Adalat) are funded by Pharmac. Several generic MR formulations are also subsidised.

In New Zealand, Adalat CR (nifedipine modified-release) and funded generic equivalents are prescribed for hypertension and angina. BPAC NZ guidelines recommend calcium channel blockers as first- or second-line agents for hypertension, particularly in older patients and those of African or Asian descent. Immediate-release nifedipine capsules are generally avoided for routine hypertension management due to rapid blood pressure changes. Grapefruit avoidance should be clearly communicated to all patients.

What is Nifedipine Used For?

Nifedipine is prescribed by healthcare professionals in New Zealand for the following indications:

• Hypertension (high blood pressure)
• Chronic stable angina and variant (Prinzmetal’s) angina
• Raynaud’s phenomenon
• Premature labour (short-term, in hospital settings)
• Hypertensive emergencies (immediate-release, with caution)

How Does Nifedipine Work?

Nifedipine is a dihydropyridine calcium channel blocker. It blocks voltage-gated calcium channels in vascular smooth muscle cells, preventing calcium entry and causing vasodilation. This reduces peripheral vascular resistance (lowering blood pressure) and dilates coronary arteries (relieving angina). Nifedipine has minimal direct effect on cardiac conduction, making it suitable for patients with certain arrhythmias.

How to Take Nifedipine

Modified-release (MR) preparations are preferred for hypertension and chronic angina — take once or twice daily as directed, swallowing whole without crushing or chewing. Immediate-release nifedipine (rarely used now) acts quickly but causes rapid blood pressure changes. Take at the same time(s) each day. Grapefruit juice significantly increases nifedipine blood levels — avoid during treatment. Food does not significantly affect absorption of MR preparations.

Common Side Effects

Like all medications, Nifedipine may cause side effects. Common side effects include:

• Peripheral oedema (ankle swelling) — very common
• Headache and flushing
• Dizziness
• Palpitations or rapid heartbeat
• Nausea and abdominal discomfort
• Gingival (gum) hyperplasia with long-term use

Serious Side Effects — Seek Medical Attention

Contact your doctor or call 111 immediately if you experience any of the following serious effects:

• Severe hypotension — dizziness, fainting
• Worsening angina (particularly with immediate-release nifedipine)
• Liver function abnormalities (rare)
• Severe skin reactions — Stevens-Johnson syndrome (rare)

Drug Interactions

Always inform your prescriber and pharmacist of all medications, supplements, and herbal products you are taking. Notable interactions with Nifedipine include:

• Grapefruit juice — significantly increases nifedipine levels; avoid
• CYP3A4 inhibitors (clarithromycin, itraconazole, ritonavir) — increase nifedipine levels
• CYP3A4 inducers (rifampicin, phenytoin, carbamazepine) — reduce nifedipine efficacy
• Beta-blockers — may cause excessive bradycardia or heart failure when combined
• Digoxin — nifedipine may increase digoxin levels
• Quinidine — nifedipine reduces quinidine levels

New Zealand Prescribing Information

In New Zealand, Adalat CR (nifedipine modified-release) and funded generic equivalents are prescribed for hypertension and angina. BPAC NZ guidelines recommend calcium channel blockers as first- or second-line agents for hypertension, particularly in older patients and those of African or Asian descent. Immediate-release nifedipine capsules are generally avoided for routine hypertension management due to rapid blood pressure changes. Grapefruit avoidance should be clearly communicated to all patients.

Frequently Asked Questions

Why should I avoid grapefruit with nifedipine?

Grapefruit and grapefruit juice contain compounds that inhibit the enzyme (CYP3A4) responsible for breaking down nifedipine in the gut and liver. This can cause nifedipine blood levels to rise significantly, potentially causing an excessive drop in blood pressure, severe flushing, headache, or palpitations. Avoid all grapefruit products while taking nifedipine.

Why are my ankles swollen since starting nifedipine?

Ankle swelling (peripheral oedema) is a very common side effect of dihydropyridine calcium channel blockers like nifedipine. It occurs because these medications dilate the small blood vessels (capillaries) in the legs, allowing fluid to leak into surrounding tissue. This is not the same as fluid retention from heart failure. Elevating your legs when resting can help. If severe, discuss with your doctor — a dose reduction or medication change may be needed.

References & Further Information

The following New Zealand and international resources were used to inform this page:

• New Zealand Formulary — Nifedipine
• Pharmac — Funded Medicines Schedule
• BPAC NZ — Managing Hypertension
• Medsafe — Adalat CR Data Sheet

Reviewed by a Registered Pharmacist — KiwiMeds New Zealand