Nifedipine: 7 things you should know
Medically reviewed by Carmen Fookes, BPharm. Last updated on Apr 10, 2020.
1. How it works
- Nifedipine inhibits the influx of calcium ions across cardiac (heart) and smooth muscle causing relaxation of these muscles and dilation (widening). The exact way nifedipine works in angina is not known; however, experts believe it helps prevent spasm of the coronary artery and reduces how hard the heart has to work to pump blood around the body, lowering its oxygen requirements. Nifedipine does not change levels of calcium in the blood.
- Nifedipine belongs to a class of medicines called calcium channel blockers (sometimes called calcium channel antagonists).
- Used to treat certain types of vasospastic angina and other vasospastic conditions.
- Also used in the treatment of chronic stable angina in patients intolerant of, or not adequately controlled by, beta-blockers or nitrates.
- Generic nifedipine is available.
If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:
- Dizziness, light-headedness, flushing, headache, weakness, nausea, heartburn and muscle cramps or tremor. Nervousness, palpitations, cough and nasal congestion may also be reported.
- Excessive and poorly tolerated hypotension (low blood pressure) is experienced by some people. The risk is greater during initial therapy or upwards dose titration and may be more common in those already taking beta-blockers. Nifedipine capsules should not be used to reduce blood pressure quickly as this may be fatal.
- Peripheral edema (fluid retention in the lower limbs) occurs in one in ten people prescribed nifedipine. Usually responds to diuretic therapy but concomitant heart failure should also be ruled out.
- Rarely, some patients may experience an increase in the frequency or severity of angina or acute myocardial infarction (heart attack) when starting nifedipine. The risk is greater in those with severe obstructive coronary artery disease.
- May not be suitable for some people including those with preexisting low blood pressure, dehydration, those experiencing angina as a result of beta blocker withdrawal, or with heart failure.
- May interact with a number of other drugs including beta-blockers, digoxin, cimetidine, fentanyl, grapefruit juice, and phenytoin. See prescribing information for a full list of drug interactions.
Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.
- May be taken with or without food. Take exactly as directed by your doctor.
- Do not take nifedipine with any grapefruit juice or other products made using grapefruit (such as marmalade).
- Your blood pressure may need to be carefully monitored during the initial administration and titration of nifedipine. Tell your doctor if you feel dizzy, particularly when going from a sitting or lying down position to standing. Dizziness may increase your risk of falls.
- May alter the results of some laboratory tests and increase bleeding time. Tell other health professionals that you are taking nifedipine.
- Do not stop taking nifedipine suddenly. Although no "rebound" effect has been reported, it is better to slowly decrease the dosage over a period of time.
- Your doctor may advise you to take sublingual nitroglycerin during the initial administration of nifedipine. Follow his/her advice.
- Talk to your doctor if you develop edema, angina pain, or any other worrying side effects soon after starting nifedipine.
6. Response and Effectiveness
- Nifedipine is quickly absorbed when taken orally and peak blood levels occur in approximately 30 minutes. It is relatively short-acting and needs to be taken three times a day.
Medicines that interact with nifedipine may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with nifedipine. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.
Common medications that may interact with nifedipine include:
- anticonvulsants, such as carbamazepine, divalproex or fosphenytoin
- antifungal agents, such as itraconazole or ketoconazole
- anti-inflammatory medications such as adalimumab
- antipsychotics, such as aripiprazole
- antivirals such as atazanavir, darunavir, delavirdine
- beta-blockers, such as atenolol, bisoprolol, labetalol, or metoprolol
- calcium-containing medications
- cancer medications
- corticosteroids, such as budesonide or dexamethasone
- medications that reduce high cholesterol, such as atorvastatin, lovastatin or simvastatin
- NSAIDs, such as diclofenac, ibuprofen, and indomethacin, may decrease the blood pressure-lowering capabilities of nifedipine
- other heart medications, such as diltiazem, or flecainide
- opioids, such as alfentanil, buprenorphine, or codeine
- St John's wort
Note that this list is not all-inclusive and includes only common medications that may interact with nifedipine. You should refer to the prescribing information for nifedipine for a complete list of interactions.
Nifedipine Revised 11/2019. Drugs.com https://www.drugs.com/ppa/nifedipine.html
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use nifedipine only for the indication prescribed.
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- Drug class: calcium channel blocking agents