Consumer medicine information

APO-Nifedipine XR

Nifedipine

BRAND INFORMATION

Brand name

APO-Nifedipine XR

Active ingredient

Nifedipine

Schedule

S4

 

Consumer medicine information (CMI) leaflet

Please read this leaflet carefully before you start using APO-Nifedipine XR.

SUMMARY CMI

APO-NIFEDIPINE XR

Consumer Medicine Information (CMI) summary

The full CMI on the next page has more details. If you are worried about using this medicine, speak to your doctor or pharmacist.

1. Why am I using APO-NIFEDIPINE XR?

APO-NIFEDIPINE XR contains the active ingredient nifedipine. APO-NIFEDIPINE XR is used to treat hypertension (high blood pressure) or to prevent chronic stable angina, a type of angina.

For more information, see Section 1. Why am I using APO-NIFEDIPINE XR? in the full CMI.

2. What should I know before I use APO-NIFEDIPINE XR?

Do not use if you have ever had an allergic reaction to nifedipine or any of the ingredients listed at the end of the CMI.

Talk to your doctor if you have any other medical conditions, take any other medicines, or are pregnant or plan to become pregnant or are breastfeeding.

For more information, see Section 2. What should I know before I use APO-NIFEDIPINE XR? in the full CMI.

3. What if I am taking other medicines?

Some medicines may interfere with APO-NIFEDIPINE XR and affect how it works.

A list of these medicines is in Section 3. What if I am taking other medicines? in the full CMI.

4. How do I use APO-NIFEDIPINE XR?

The usual starting dose is 30mg (one 30mg tablet) daily.

More instructions can be found in Section 4. How do I use APO-NIFEDIPINE XR? in the full CMI.

5. What should I know while using APO-NIFEDIPINE XR?

Things you should do
  • Remind any doctor, dentist or pharmacist you visit that you are using APO-NIFEDIPINE XR.
  • If you are about to be started on any new medication, tell your doctor that you are taking APO-NIFEDIPINE XR.
  • Tell your doctor you are pregnant or planning to become pregnant.
  • Tell your doctor you are breast-feeding or are planning to breast-feed.
  • Tell your doctor you are about to have any blood or urine tests, or a Barium Contrast X ray.
  • Tell your doctor you are going to have surgery or an anesthetic or are going into hospital.
Things you should not do
  • Do not stop taking this medicine suddenly, or change the dosage, without first checking with your doctor.
  • Do not take this medicine to treat any other condition unless your doctor or pharmacist tells you to.
  • Do not give this medicine to anyone, even if their symptoms seem similar to yours.
  • You should not eat grapefruit or drink grapefruit juice while you are taking nifedipine or for 3 days before starting to take nifedipine.
Driving or using machines
  • Be careful when driving or operating machinery until you know how this medicine affects you.
  • Nifedipine may cause dizziness, light-headedness or fainting in some patients. If affected, do not drive a vehicle or operate machinery.
Drinking alcohol
  • Your doctor may advise you to limit your alcohol intake.
Looking after your medicine
  • Keep your medicine in a cool dry place where the temperature will stay below 25°C.
  • Keep your medicine in its original packaging until it is time to take it.

For more information, see Section 5. What should I know while using APO-NIFEDIPINE XR? in the full CMI.

6. Are there any side effects?

Common and mostly mild side effects include headache, feeling dizzy, fast or irregular heartbeats, constipation, general swelling and/or swelling of arms, ankles or legs, generally feeling unwell or in pain and jaundice. Refer to the CMI for all side effects. For more information, including what to do if you have any side effects, see Section 6. Are there any side effects? in the full CMI.



FULL CMI

APO-NIFEDIPINE XR

Active ingredient: nifedipine

Consumer Medicine Information (CMI)

This leaflet provides important information about using APO-NIFEDIPINE XR. You should also speak to your doctor or pharmacist if you would like further information or if you have any concerns or questions about using APO-NIFEDIPINE XR.

Where to find information in this leaflet:

1. Why am I using APO-NIFEDIPINE XR?
2. What should I know before I use APO-NIFEDIPINE XR?
3. What if I am taking other medicines?
4. How do I use APO-NIFEDIPINE XR?
5. What should I know while using APO-NIFEDIPINE XR?
6. Are there any side effects?
7. Product details

1. Why am I using APO-NIFEDIPINE XR?

APO-NIFEDIPINE XR contains the active ingredient nifedipine. Nifedipine belongs to a group of medicines called calcium channel blockers. They work by relaxing and opening up the blood vessels in the body to lower blood pressure and to improve the supply of blood and oxygen to the heart.

APO-NIFEDIPINE XR is used to treat hypertension (high blood pressure) or to prevent chronic stable angina, a type of angina.

APO-Nifedipine XR is designed to allow the slow release of the nifedipine from the tablet after it is taken.

There is no evidence that this medicine is addictive.

2. What should I know before I use APO-NIFEDIPINE XR?

Warnings

Do not use APO-NIFEDIPINE XR if you have had the following:

  • a heart attack in the last 8 days
  • cardiogenic shock (very low blood pressure due to a failing heart)
  • a Kock Pouch (an ileostomy)
  • the rare inherited problems of galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption. These tablets contain lactose
  • you are taking another medicine called rifampicin, an antibiotic
  • have had an allergic reaction to nifedipine, similar medicines such as amlodipine, felodipine, lercanidipine, nimodipine and isradipine or any of the ingredients listed at the end of this leaflet.

Check with your doctor if you:

  • have allergies to any other medicines or any other substances, such as foods, preservatives or dyes.
  • have any medical conditions, especially the following:
    - heart problems such as heart failure, angina or narrowing of any of the blood vessels going into or out of the heart
    - other heart or blood vessel disorders
    - low blood pressure
    - stroke
    - mini-stroke (also known as TIA transient ischaemic attack)
    - diabetes
    - liver problems
    - kidney disease or having dialysis
    - narrowing of your oesophagus or intestine, e.g. due to previous injury, infection or surgery
    - prolonged diarrhoea or other bowel problems, e.g. Crohn's Disease or Ulcerative Colitis
    - surgery on your bowel
  • You are currently pregnant or breast-feeding or you plan to become pregnant or breast-feed. Your doctor will discuss alternative medicines with you, as you must not take nifedipine whilst pregnant or breast feeding.
  • You are planning to have surgery or an anaesthetic or are going into hospital.
  • You are currently receiving or are planning to receive dental treatment.
  • You are taking or are planning to take any other medicines. This includes vitamins and supplements that are available from your pharmacy, supermarket or health food shop.

You should not eat grapefruit or drink grapefruit juice while you are taking nifedipine or for 3 days before starting to take nifedipine, because this may cause your blood pressure to drop too low.

During treatment, you may be at risk of developing certain side effects. It is important you understand these risks and how to monitor for them. See additional information under Section 6. Are there any side effects?

Pregnancy and breastfeeding

Check with your doctor if you are pregnant or intend to become pregnant.

Talk to your doctor if you are breastfeeding or intend to breastfeed.

Nifedipine may affect your developing baby if you take it during pregnancy.

Nifedipine may pass into human breast milk.

3. What if I am taking other medicines?

Tell your doctor or pharmacist if you are taking any other medicines, including any medicines, vitamins or supplements that you buy without a prescription from your pharmacy, supermarket or health food shop.

Some medicines may interfere with APO-NIFEDIPINE XR and affect how it works. These include:

  • Beta blockers, e.g. metoprolol, atenolol
  • other medicines used to treat high blood pressure or angina, e.g. diltiazem
  • medicines used to treat arrhythmia (fast or irregular heartbeats), e.g. quinidine
  • other medicines used to treat heart disease, e.g. digoxin
  • some medicines used to treat stomach ulcers and heartburn, e.g. cimetidine, cisapride
  • rifampicin, used to treat tuberculosis and other serious infections
  • other medicines used to treat bacterial infections, e.g. erythromycin, quinupristin, dalfopristin
  • medicines used to treat fungal infections, e.g. ketoconazole
  • medicines used to treat HIV, e.g. ritonavir
  • medicines used to treat epilepsy, e.g. phenytoin, carbamazepine, valproic acid, phenobarbitone
  • anti-depressants, e.g. fluoxetine, nefazodone
  • tacrolimus, used to prevent rejection after organ transplant. Tacrolimus is a medicine used after organ transplant.

If you are taking any of these you may need a different dose or you may need to take different medicines.

Other medicines not listed above may also interact with nifedipine.

Check with your doctor or pharmacist if you are not sure about what medicines, vitamins or supplements you are taking and if these affect APO-NIFEDIPINE XR.

4. How do I use APO-Nifedipine XR?

How much to take / use

  • Follow carefully all directions given to you by your doctor or pharmacist. Their instructions may be different to the information in this leaflet.
  • Your doctor or pharmacist will tell you how much of this medicine you should take. This will depend on your condition and whether you are taking any other medicines.
  • The usual starting dose is 30 mg (one 30 mg tablet) daily.
  • Your doctor may increase the dose slowly over several weeks depending on how you respond to this medicine. If you are being treated for high blood pressure the maximum dose is 120 mg, and if you have chronic angina, the maximum dose is 90 mg.
  • If a dose less than 30 mg is needed you will have to take a different brand of nifedipine.
  • If you have liver problems or are taking certain other medicines or you are elderly or of South Asian origin, your doctor may prescribe a lower dose.
  • Children under 18 years of age must not take this medicine.
  • Do not stop taking your medicine suddenly or change your dosage without first checking with your doctor.
  • Follow the instructions provided and use APO-NIFEDIPINE XR until your doctor tells you to stop.

When to take APO-NIFEDIPINE XR

  • Take this medicine at the same time each day, usually in the morning.
  • Taking it at the same time each day will have the best effect and will also help you remember when to take it.
  • It does not matter if you take it before, with or after food.

How to take APO-NIFEDIPINE XR

Swallow the tablets whole with a glass of liquid. Do not crush, chew or break up the tablets.

You should not eat grapefruit or drink grapefruit juice while you are taking Nifedipine or for 3 days before starting to take nifedipine, because this may cause your blood pressure to drop too low.

If you forget to use APO-NIFEDIPINE XR

APO-NIFEDIPINE XR should be used regularly at the same time each day. If you miss your dose at the usual time, take it as soon as you remember, waiting 12 hours before taking your next dose.

If it is almost time (within 12 hours) for your next dose, skip the dose you missed and take your next dose when you are meant to.

Do not take a double dose to make up for the dose you missed.

If you use too much APO-NIFEDIPINE XR

If you think that you have used too much APO-NIFEDIPINE XR, you may need urgent medical attention.

You should immediately:

  • phone the Poisons Information Centre
    (by calling 13 11 26), or
  • contact your doctor, or
  • go to the Emergency Department at your nearest hospital.

You should do this even if there are no signs of discomfort or poisoning.

If you take too much nifedipine, you may feel dizzy or experience flushing and fainting due to a drop in blood pressure, irregular or fast or slow heart beats, fast or troubled breathing and even loss of consciousness.

5. What should I know while using APO-NIFEDIPINE XR?

Things you should do

  • Take the tablets exactly as you are told to by your doctor. If you do not follow your doctor's instruction you may not get control of your blood pressure or angina.
  • Tell your doctor if you continue to have chest pain or angina attacks or if they become more frequent while you are taking APO-NIFEDIPINE XR.
  • Tell your doctor that you are taking this medicine if:
    - you are about to be started on any new medicine.
    - you are pregnant or are planning to become pregnant.
    - you are breastfeeding or are planning to breast-feed.
    - you are about to have any blood or urine tests, or Barium Contrast X ray.
    - you are going to have surgery or an anesthetic or are going into hospital.
  • If you are taking a beta blocker and your doctor has told you to stop taking it, make sure you gradually stop taking the beta blocker over few days.
  • Your doctor may do tests to make sure the medicine is working and to prevent side effects, especially if you are taking other tablets as well or you have other medical conditions. Go to your doctor regularly for a check-up.
  • Remind any doctor, dentist or pharmacist you visit that you are using APO-NIFEDIPINE XR.
  • Get up slowly when getting out of bed or standing up. This is to avoid becoming light-headed, dizzy or faint. If you feel light-headed or dizzy, this may be because your blood pressure is falling suddenly. Standing up slowly, especially when you get up from sleeping or sitting, will help your body get used to the change in position and blood pressure. If this problem gets worse or continues, talk to your doctor.
  • Tell your doctor if, for any reason, you have not taken your medicine exactly as directed.
    Otherwise, your doctor may think that it is not working and change your treatment unnecessarily.

Call your doctor straight away if you:

  • Are having an allergic reaction to APO-NIFEDIPINE XR. Do not take any more of this medicine and you're your doctor immediately or go the Accident and Emergency department at your nearest hospital.
    Symptoms of allergic reactions may include some or all of the following:
    - Cough, shortness of breath, wheezing or difficulty breathing
    - Swelling of the face, lips, tongue, or other parts of the body
    - Rash, itching or hives on the skin
    - Fainting
    - Hayfever-like symptoms

Things you should not do

  • Do not give this medicine to anyone else, even if their symptoms seem similar to yours.
  • Do not take your medicine to treat any other condition unless your doctor or pharmacist tells you to.
  • Do not stop using this medicine suddenly, or change the dosage, without first checking with your doctor.

Driving or using machines

Be careful before you drive or use any machines or tools until you know how this medicine affects you.

APO-NIFEDIPINE XR may cause dizziness, light-headedness or fainting in some people, especially when they start taking the medicine, when changing the dose in some cases when taking it with alcohol. If affected, do not drive a vehicle, operate machinery or do anything else that could be dangerous.

Drinking alcohol

Tell your doctor if you drink alcohol.

Your doctor may advise you to limit your alcohol intake.

Looking after your medicine

  • Keep your medicine in its original packaging until it is time to take it. If you take your medicine out of its original packaging it may not keep well.
  • Keep your medicine in a cool dry place where the temperature will stay below 25°C.

Follow the instructions in the carton on how to take care of your medicine properly.

Store it in a cool dry place away from moisture, heat or sunlight; for example, do not store it:

  • in the bathroom or near a sink, or
  • in the car or on window sills. Heat and dampness can destroy some medicines.

Keep it where young children cannot reach it.

A locked cupboard at least one-and-a-half metres above the ground is a good place to store medicines.

Getting rid of any unwanted medicine

If you no longer need to use this medicine or it is out of date, take it to any pharmacy for safe disposal.

Do not use this medicine after the expiry date.

6. Are there any side effects?

All medicines can have side effects. If you do experience any side effects, most of them are minor and temporary. However, some side effects may need medical attention.

See the information below and, if you need to, ask your doctor or pharmacist if you have any further questions about side effects.

Less serious side effects

Less serious side effectsWhat to do
  • Headache
  • Feeling dizzy
  • Fast or irregular heartbeats
  • constipation
  • general swelling and/or swelling of arms, ankles or legs
  • generally feeling unwell or in pain
  • jaundice
Speak to your doctor if you have any of these less serious side effects and they worry you.

Serious side effects

Serious side effectsWhat to do
  • fast, thumping or irregular heartbeat
  • problems breathing
  • rash, itching or hives on the skin.
  • swelling of the face, lips, tongue, or other parts of the body
  • signs of liver problems such as yellowing of the skin and/or eyes (jaundice)
  • chest pain
  • signs of frequent infections such as fever, severe chills, sore throat, or mouth ulcers
Call your doctor straight away, or go straight to the Emergency Department at your nearest hospital if you notice any of these serious side effects.

Tell your doctor or pharmacist if you notice anything else that may be making you feel unwell.

Other side effects not listed here may occur in some people.

Reporting side effects

After you have received medical advice for any side effects you experience, you can report side effects to the Therapeutic Goods Administration online at www.tga.gov.au/reporting-problems. By reporting side effects, you can help provide more information on the safety of this medicine.

Always make sure you speak to your doctor or pharmacist before you decide to stop taking any of your medicines.

7. Product details

This medicine is only available with a doctor's prescription.

What APO-Nifedipine XR contains

Active ingredient
(main ingredient)		nifedipine
Other ingredients
(inactive ingredients)
  • purified talc
  • lactose monohydrate
  • povidone
  • carbomer 934P
  • hypromellose
  • colloidal anhydrous silica
  • magnesium stearate
  • titanium dioxide
  • iron oxide red CI77491
  • macrogol 4000
  • Eudragit E100.
Potential allergenslactose

Do not take this medicine if you are allergic to any of these ingredients.

This medicine is gluten-free.

What APO-Nifedipine XR looks like

APO-NIFEDIPINE XR 30 mg tablets: Round, pale red tablet marked “30” on one side. (Aust R 152207).

APO-NIFEDIPINE XR 60 mg tablets: Round, pale red tablet marked “60” on one side. (Aust R 152208).

Who distributes APO-Nifedipine XR

Arrotex Pharmaceuticals Pty Ltd
15-17 Chapel Street
Cremorne VIC 3121
www.arrotex.com.au

This leaflet was prepared in September 2024.

Published by MIMS November 2024

BRAND INFORMATION

Brand name

APO-Nifedipine XR

Active ingredient

Nifedipine

Schedule

S4

 

1 Name of Medicine

Nifedipine.

2 Qualitative and Quantitative Composition

APO-Nifedipine XR 30 mg tablets contain 30 mg of nifedipine.
APO-Nifedipine XR 60 mg tablets contain 60 mg of nifedipine.

Excipients with known effect.

Lactose monohydrate. For the full list of excipients, see Section 6.1 List of Excipients.

3 Pharmaceutical Form

APO-Nifedipine XR 30 mg tablets are pale red, round biconvex tablet marked "30" on one side.
APO-Nifedipine XR 60 mg tablets are pale red, round biconvex tablet marked "60" on one side.

4 Clinical Particulars

4.1 Therapeutic Indications

Treatment of hypertension.
Prophylaxis of chronic stable angina pectoris.

4.2 Dose and Method of Administration

As far as possible the treatment must be tailored to the needs of the individual and depending on the clinical picture in each case, the basic dose must be introduced gradually. In patients with impaired liver function, careful monitoring is advised and, in severe cases, a dose reduction may be necessary.
The tablets are swallowed whole, without chewing or being broken up, with a little liquid, independently of mealtimes. Grapefruit juice is to be avoided.

Hypertension.

APO-Nifedipine XR should be initiated with 30 mg once daily. A starting dose of 20 mg may be considered when medically indicated. Monitoring of trough blood pressure should be done initially to ensure blood pressure control lasts over the dosing interval.
Depending on the severity of the disease and the patient's response, the dose can be the dose can be decreased to 20 mg or increased in stages to 120 mg daily. In general, titration should proceed over a 7 to 14 day period so that the doctor can fully assess the response to each dose level and monitor the blood pressure before proceeding to higher doses. Since steady-state levels are achieved on the second day of dosing, titration may proceed more rapidly if symptoms so warrant, provided the patient is assessed frequently. Titration to doses above 120 mg/day is not recommended.

Note.

Nifedipine 20 mg tablets are not available with this brand.

Chronic stable angina.

APO-Nifedipine XR should be initiated with 30 mg once daily. If necessary, the dosage can be increased in stages to a maximum of 90 mg once daily. Experience with doses greater than 90 mg/day in patients with angina is limited.
The initiation of APO-Nifedipine XR therapy in South Asian patients who have not previously taken nifedipine should start at low doses (see Section 5.2 Pharmacokinetic Properties).
Coadministration with CYP3A4 inhibitors or inducers may require nifedipine dose adjustment or for nifedipine not to be used at all (see Section 4.5 Interactions with Other Medicines and Other Forms of Interactions).

Children and adolescents.

The safety and efficacy of APO-Nifedipine XR in children and adolescents below 18 years has not been established.

Elderly patients.

Caution should be exercised in the use of APO-Nifedipine XR in elderly patients, especially those with a history of hypotension or cerebral vascular insufficiency. Lower doses may be required in patients with reduced drug clearance.

4.3 Contraindications

Known hypersensitivity to nifedipine or related dihydropyridine calcium channel blockers or to any of the excipients.
Pregnancy and lactation.
Cardiogenic shock.
Kock pouch (ileostomy after proctocolectomy).
Concomitant administration with rifampicin (see Section 4.5 Interactions with Other Medicines and Other Forms of Interactions).
Within the first eight days of an acute episode of myocardial infarction.

4.4 Special Warnings and Precautions for Use

Excessive hypotension.

Caution should be exercised in patients with severe hypotension (systolic pressure < 90 mmHg) as there is a risk of further reduction in blood pressure.
APO-Nifedipine XR may be used in combination with beta-blocking drugs and other antihypertensive agents, but the possibility of potentiation of existing antihypertensive therapy should be noted.

Increased angina and/or myocardial infarction.

Rare cases of increased frequency, duration and/or severity of angina or acute myocardial infarction on starting nifedipine or at the time of dosage increase have been reported. These well documented cases are mainly in those patients who have severe obstructive coronary artery disease. The mechanism of this effect is not established.

Chest pain.

There have been a small number of reports of chest pain not associated with myocardial infarction (in certain circumstances, angina pectoris-like symptoms) occurring soon after administration of a single dose. In this case, APO-Nifedipine XR should be withdrawn if a causal relationship is suspected.

Beta-blocker withdrawal.

When nifedipine is administered simultaneously with beta-blockers the patient should be carefully monitored, since deterioration of heart failure may develop in isolated cases.
Nifedipine extended release tablets have no inherent antiarrhythmic action and therefore give no protection against any arrhythmias that may result from abrupt withdrawal of beta-blockers. Any such withdrawal of beta-blockers should be achieved gradually over a period of several days.

Congestive heart failure.

The onset of heart failure has occasionally been observed during clinical use. Care should be observed with patients whose cardiac reserve is poor or who are receiving large doses of beta-blockers.

Peripheral oedema.

Mild to moderate peripheral oedema occurs in a dose dependent manner with an incidence ranging from approximately 10% with nifedipine extended release tablets 30 mg daily to about 33% at 120 mg daily. This is due to arteriolar vasodilatation and is not due to heart failure. With patients whose hypertension is complicated by congestive heart failure, care should be taken to differentiate this peripheral oedema from the effects of increasing left ventricular dysfunction.

Hypotension/heart rate.

Because nifedipine extended release tablets are an arterial and arteriolar vasodilator, hypotension and a compensatory increase in heart rate may occur. Thus blood pressure and heart rate should be monitored carefully during nifedipine therapy. Close monitoring is especially recommended for patients who are prone to develop hypotension, those with a history of cerebrovascular insufficiency and those who are taking medications that are known to lower blood pressure.

Acute treatment of angina pectoris.

APO-Nifedipine XR is not suitable for the acute treatment of angina pectoris due to delayed absorption of the drug from the modified release dosage formulation.

Diabetes.

Treatment with nifedipine can theoretically impair glucose metabolism, which may be of clinical relevance in some cases.

Aortic stenosis.

Patients with severe aortic stenosis are at risk of developing heart failure or hypotension because of the vasodilating effects of APO-Nifedipine XR.

Severe gastrointestinal narrowing.

As with any other nondeformable material, caution should be used when administering APO-Nifedipine XR to patients with a previous history of severe gastrointestinal narrowing or obstruction. Bezoars can occur in very rare cases and may require surgical intervention.
There have been rare reports of bowel obstruction requiring surgery in patients with known oesophageal stricture, small bowel stenosis and after gastropexy, due to the nondeformable nature of nifedipine extended release tablets. In single cases obstructive symptoms have been described without known history of gastrointestinal disorders.

Shortened transit times.

The sustained release of APO-Nifedipine XR may be impaired in chronic diarrhoea (e.g. Crohn's disease, ulcerative colitis) or short bowel syndrome, when the gastrointestinal transit time is less than 18 to 22 hours. Monitoring of trough blood pressure (24 hour) is advised in these patients. If control of the trough blood pressure is not satisfactory, then conventional nifedipine tablets taken twice daily should be used.

Other nifedipine formulations.

APO-Nifedipine XR modified release tablets are not bioequivalent to immediate release nifedipine capsules and tablets and patients should be carefully monitored if it is decided to switch between immediate release and modified release nifedipine or vice versa. APO-Nifedipine XR may not be bioequivalent to modified release nifedipine preparations available overseas.

Use in hepatic impairment.

In patients with impaired liver function, careful monitoring and, in severe cases, a dose reduction may be necessary. The total systemic plasma clearance is reduced and elimination half-life is increased in severe liver disease.

Use in the elderly.

Caution should be exercised in the use of APO-Nifedipine XR in elderly patients, especially those with a history of hypotension or cerebrovascular insufficiency. Lower doses may be required in patients with reduced drug clearance.

Paediatric use.

The safety and efficacy of APO-Nifedipine XR in children and adolescents below 18 years has not been established.

Effects on laboratory tests.

Barium contrast X-ray.

Nifedipine extended release tablets may cause false positive findings (e.g. filling defects interpreted as polyps) when barium contrast X-ray is undertaken.

Spectrophotometric test for vanillylmandelic acid.

Nifedipine may falsely increase spectrophotometric assay values of urinary vanillylmandelic acid (VMA). However measurement with high pressure liquid chromatography (HPLC) is unaffected.
Rare, usually transient, but occasionally significant elevations of enzymes such as alkaline phosphatase (AP), creatine phosphokinase (CPK), lactate dehydrogenase (LDH), AST (SGOT) and ALT (SGPT) have been noted. The relationship to nifedipine therapy is uncertain in most cases, but probable in some. These laboratory abnormalities have rarely been associated with clinical symptoms, however cholestasis with or without jaundice has been reported. Rare instances of allergic hepatitis have been reported.
Nifedipine, like other calcium channel blockers, decreases platelet aggregation in vitro. A limited number of clinical studies have demonstrated a moderate but statistically significant decrease in platelet aggregation and increase in bleeding time in nifedipine treated patients. This is thought to be a function of inhibition of calcium transport across the platelet membrane. No clinical significance for these findings has been demonstrated.

4.5 Interactions with Other Medicines and Other Forms of Interactions

The blood pressure lowering effect of nifedipine may be potentiated by other antihypertensive drugs.
Nifedipine is metabolised via the cytochrome P450 3A4 (CYP3A4) system, located in the intestinal mucosa and the liver. Drugs that are known to inhibit or induce CYP3A4 may therefore alter the first pass or the clearance of nifedipine.
Drugs which are inhibitors of CYP3A4 and therefore may lead to increased plasma concentrations of nifedipine are e.g.: macrolide antibiotics (e.g. erythromycin); anti-HIV protease inhibitors (ritonavir); azole antimycotics (e.g. ketoconazole); the antidepressants nefazodone and fluoxetine; quinupristin/dalfopristin; valproic acid; cimetidine.
Upon co-administration with these drugs, the blood pressure should be monitored and, if necessary, a reduction of nifedipine dose should be considered.

Drugs that affect nifedipine.

Nifedipine is metabolised via CYP3A4, located in the intestinal mucosa and the liver. Medicines that are known to inhibit or induce CYP3A4 may therefore alter the first pass of clearance of nifedipine.
The extent as well as the duration of interactions should be taken into account when administering nifedipine together with the following drugs:

Rifampicin.

Rifampicin, strongly induces CYP3A4. Upon co-administration with rifampicin, the bioavailability of nifedipine is distinctly reduced and thus its efficacy is also reduced. The use of rifampicin in combination with nifedipine is contraindicated.
Upon co-administration of the following weak to moderate inhibitors of CYP3A4 the blood pressure should be monitored and, if necessary, a reduction in the nifedipine dose considered (see Section 4.2 Dose and Method of Administration).

Macrolide antibiotics (e.g. erythromycin).

No interaction studies have been carried out between nifedipine and erythromycin. Certain macrolide antibiotics are known to inhibit CYP3A4 mediated metabolism of other medicines, and could increase plasma concentrations of nifedipine if administered concomitantly. Azithromycin, although structurally related to the class of macrolide antibiotics does not inhibit CYP3A4.

Anti-HIV protease inhibitors.

A clinical study investigating the potential interaction between nifedipine and certain anti-HIV protease inhibitors has not yet been performed. Medicines of this class are known to inhibit CYP3A4. In addition, drugs of this class have been shown to inhibit in vitro the CYP3A4 mediated metabolism of nifedipine. When administered together with nifedipine, a substantial increase in plasma concentrations of nifedipine due to a decreased first-pass metabolism and decreased elimination cannot be excluded.

Ketoconazole, itraconazole, fluconazole.

A formal interaction study investigating the potential of a drug interaction between nifedipine and these drugs has not yet been performed. These drugs are known to inhibit CYP3A4. When administered orally with nifedipine, a substantial increase in systemic bioavailability of nifedipine is possible. Co-administration of these drugs with nifedipine requires careful monitoring and, if necessary, a reduction in the nifedipine dose should be considered.

Fluoxetine.

A clinical study investigating the potential of a drug interaction between nifedipine and fluoxetine has not yet been performed. Fluoxetine has been shown to inhibit in vitro the CYP3A4 mediated metabolism of nifedipine. Therefore, an increase of nifedipine plasma concentrations upon co-administration of both medicines cannot be excluded (see Section 4.4 Special Warnings and Precautions for Use).

Nefazodone.

A clinical study investigating the potential of a drug interaction between nifedipine and nefazodone has not yet been performed. Nefazodone is known to inhibit the cytochrome P450 3A4 mediated metabolism of other drugs. Therefore, an increase of nifedipine plasma concentrations upon co-administration of both drugs cannot be excluded. When nefazodone is given together with nifedipine, the blood pressure should be monitored and, if necessary, a reduction in the nifedipine dose considered.

Quinupristin/dalfopristin.

Simultaneous administration of quinupristin/dalfopristin and nifedipine may lead to increased plasma concentrations of nifedipine, with the effect varying markedly between individuals. Upon co-administration of both drugs, the blood pressure should be monitored and, if necessary, a reduction of the nifedipine dose considered.

Sodium valproate.

No formal studies have been performed to investigate the interaction of nifedipine with sodium valproate, but it has been shown to increase the plasma concentrations of another dihydropyridine calcium channel blocker (nimodipine) through enzyme inhibition. Therefore, an increase in the plasma concentrations of nifedipine and hence an increase in efficacy is possible.

Cimetidine.

Elevation of plasma nifedipine levels during cimetidine administration has been reported. It is suggested that patients taking nifedipine and cimetidine should be carefully monitored. In case of hypotension, the dosage of nifedipine should be reduced or the patient should be treated with ranitidine, as the interaction with this drug and nifedipine is less pronounced.

Diltiazem.

Diltiazem decreases the clearance of nifedipine and hence increases plasma nifedipine levels. Therefore, caution should be exercised when the two drugs are used concomitantly and a reduction in the dose of nifedipine may be necessary.
Further studies.

Cisapride.

Simultaneous administration of cisapride and nifedipine may lead to increased plasma concentrations of nifedipine. Blood pressure should be monitored upon co-administration of both drugs, and the nifedipine dose reduced if necessary.
CYP3A4-inducing anti-epileptic drugs such as phenytoin, carbamazepine and phenobarbital (phenobarbitone).

Phenytoin.

Phenytoin induces CYP3A4. Co-administration of phenytoin with nifedipine reduces the bioavailability of nifedipine. When both drugs are concomitantly administered, the clinical response to nifedipine should be monitored and an increase in the nifedipine dose considered, if necessary. If the dose of nifedipine is increased during co-administration of both drugs, a reduction of the nifedipine dose should be considered when phenytoin is discontinued. No formal studies have been performed to investigate the potential interaction between nifedipine and carbamazepine or phenobarbital (phenobarbitone). As both drugs have been shown to reduce the plasma concentrations of the structurally similar calcium channel blocker, nimodipine, through enzyme induction, a decrease in nifedipine plasma concentrations and hence a decrease in efficacy cannot be excluded.

Effects of nifedipine on other drugs.

Blood pressure lowering drugs.

Nifedipine may increase the blood pressure lowering effect of concomitant applied antihypertensives, such as: diuretics; β-blockers; ACE-inhibitors; angiotensin I (ATI) receptor-antagonists; other calcium antagonists; α-adrenergic blocking agents; PDE5 inhibitors; α-methyldopa.
When nifedipine is used in conjunction with β-receptor blockers, patients should be carefully monitored since deterioration of heart failure is also known to develop in isolated cases.

Digoxin.

The simultaneous administration of nifedipine and digoxin can lead to reduced digoxin clearance and hence an increase in the plasma digoxin level. It is recommended that digoxin levels be monitored when initiating, adjusting and discontinuing nifedipine and, if necessary, the dose of digoxin adjusted.

Quinidine.

Quinidine levels have been observed to decrease upon the introduction of nifedipine and increase upon its withdrawal. For this reason, it is recommended that when nifedipine is either added to quinidine therapy or withdrawn from it, quinidine concentrations are monitored and the dose adjusted accordingly. Some authors reported increased plasma levels of nifedipine upon co-administration of both drugs, while others did not observe an alteration in the pharmacokinetics of nifedipine. Therefore, if quinidine is added to existing nifedipine therapy, blood pressure should be monitored and if necessary the dose of nifedipine should be reduced.

Tacrolimus.

Tacrolimus is metabolised by CYP3A4. Published data indicate that the dose of nifedipine administered simultaneously with tacrolimus may be reduced in individual cases. Upon co-administration of both drugs, the tacrolimus plasma concentrations should be monitored and, if necessary, a reduction in the tacrolimus dose should be considered.

Coumarin anticoagulants.

There have been rare reports of increased prothrombin time when nifedipine was administered to patients taking coumarin anticoagulants. However, the relationship to nifedipine therapy is uncertain.

Beta-blockers and nitrates.

Although there is a possibility of additive effects with antihypertensive and negative inotropic agents, nifedipine extended release tablets may be used in conjunction with nitrates and beta-blocking drugs. Patients should be carefully monitored when such concomitant therapies are initiated.

Others.

Case reports of increased plasma theophylline concentrations due to nifedipine administration have been reported. Nifedipine has also been reported to have a potentiating effect on terbutaline and salbutamol induced bronchodilation in asthmatics.

Carbamazepine, phenobarbitone.

No formal studies have been performed to investigate the interaction of nifedipine with these drugs. These drugs have been shown to reduce the plasma concentrations of another dihydropyridine calcium channel blocker (nimodipine) through enzyme induction. Therefore, a decrease in the plasma concentrations of nifedipine and hence a decrease in efficacy is possible.

Interactions shown not to exist.

In drug interaction studies, aspirin, omeprazole, pantoprazole, ranitidine and cerivastatin did not have clinically significant effects on the pharmacokinetics of nifedipine. Nifedipine did not have clinically significant effects on the pharmacokinetics of cerivastatin, or on the effect of aspirin 100 mg on platelet aggregation and bleeding time.

Candesartan cilexetil, irbesartan, doxazosin.

The blood pressure lowering effect of these agents may be potentiated by co-administration with nifedipine, so caution should be used in initiating combination therapy. Concomitant administration of irbesartan or doxazosin and nifedipine has no effect on the pharmacokinetics of nifedipine, and concomitant administration of candesartan cilexetil and nifedipine has no effect on the pharmacokinetics of either drug.

Drug-food interactions.

Grapefruit juice.

Grapefruit juice inhibits the cytochrome P450 3A4 system. Administration of nifedipine together with grapefruit juice thus results in elevated plasma concentrations of nifedipine due to a decreased first pass metabolism. As a consequence, the blood pressure lowering effect may be increased. After regular intake of grapefruit juice this effect may last for at least 3 days after the last ingestion of grapefruit juice.
Ingestion of grapefruit/grapefruit juice is, therefore, to be avoided while taking nifedipine.

Other forms of interactions.

Barium contrast X-ray.

Nifedipine may cause false positive findings (e.g. filling defects interpreted as polyp) when barium contrast X-ray is undertaken.

Spectrophotometric test for vanillylmandelic acid.

Nifedipine may falsely increase spectrophotometric assay values of urinary vanillylmandelic acid. However, measurement with HPLC is unaffected.

4.6 Fertility, Pregnancy and Lactation

Effects on fertility.

In isolated cases of in vitro fertilisation, calcium channel blockers like nifedipine have been associated with reversible biochemical changes in the head section of the spermatozoa that may result in impaired sperm function. In men who are repeatedly unsuccessful in fathering a child by in vitro fertilisation, and where no other explanation can be found, the use of calcium channel blockers such as nifedipine should be considered as a possible cause.
(Category C)
Nifedipine is contraindicated throughout pregnancy. Drugs in this class carry the potential to produce foetal hypoxia, caesarean deliveries, prematurity and intrauterine growth retardation, which may be associated with maternal hypotension.
Nifedipine has been shown to produce teratogenic findings in rats, mice and rabbits, including digital anomalies, malformation of the extremities, cleft palates, cleft sternum and malformation of the ribs. Digital anomalies are possibly a result of compromised uterine blood flow. Nifedipine administration has been associated with a variety of embryotoxic, placentotoxic and fetotoxic effects, including stunted foetuses (rats, mice, rabbits), small placentas and underdeveloped chorionic villi (monkeys), embryonic and foetal deaths (rats, mice, rabbits) and prolonged pregnancy/ decreased neonatal survival (rats; not evaluated in other species). All of the doses associated with the teratogenic, embryotoxic or fetotoxic effects in animals were maternally toxic and several times the recommended maximum dose for humans. There are no adequate and well controlled studies in pregnant women.
Acute pulmonary oedema has been observed when calcium channel blockers, among others nifedipine (primarily in IR formulation), have been used as a tocolytic agent during pregnancy, especially in cases of multiple pregnancy (twins or more), with the intravenous route and/or concomitant use of beta-2 agonists.
Category C: Drugs which, owing to their pharmacological effects, have caused or may be suspected of causing, harmful effects on the human foetus or neonate without causing malformations. These effects may be reversible. Accompanying texts should be consulted for further details.
 Nifedipine passes into the breast milk. So far, insufficient evidence is available as to whether nifedipine has an effect on breastfed infants. Breastfeeding should be stopped first if nifedipine treatment becomes necessary during the breastfeeding period.

4.7 Effects on Ability to Drive and Use Machines

Reactions to the drug, which vary in intensity from individual to individual, can impair the ability to drive or to operate machinery. This applies particularly at the start of treatment, on changing doses, and in combination with alcohol.

4.8 Adverse Effects (Undesirable Effects)

Clinical trial data.

(ADRs) based on placebo-controlled studies with nifedipine sorted by CIOMS III categories of frequency (clinical trial database: nifedipine n = 6,486; placebo n = 5,326) are listed below.
Reactions occurring in greater than or equal to 1% and < 10% of patients.

Cardiovascular system.

Palpitation.

Digestive system.

Constipation.

Nervous system.

Headache, dizziness.

General disorders and administration site conditions.

Feeling unwell, asthenia.
Reactions occurring in greater than or equal to 0.1% and < 1% of patients.

Immune system disorders.

Allergic reaction, allergic oedema/angioedema (incl. larynx oedema*).

Psychiatric disorders.

Anxiety reactions, sleep disorders.

Cardiovascular system.

Chest pain, angina pectoris, tachycardia.

Digestive system.

Diarrhea, dry mouth, dyspepsia, flatulence, nausea, vomiting, gastrointestinal pain.

Hepatobiliary disorders.

Increase in transaminases.

Musculoskeletal system.

Leg cramps, muscle cramps, joint swelling.

Nervous system.

Paraesthesia, somnolence, vertigo, migraine, tremor.

Eye disorders.

Visual disturbances.

Respiratory system.

Dyspnoea, nosebleed, nasal congestion.

Skin and appendages.

Pruritus, rash, erythema.

Urogenital system.

Polyuria, dysuria.

Reproductive system and breast disorders.

Erectile dysfunction.

General disorders and administration site conditions.

Unspecific pain, chills, leg pain.
*May result in life-threatening outcome.
Reactions occurring in greater than or equal to 0.01% and < 0.1% of patients.

Immune system disorders.

Urticaria.

Cardiovascular system.

Chest pain substernal, cardiovascular disorder.

Digestive system.

Anorexia, eructation, gastrointestinal disorder, gingivitis, GGT increased, gingival hyperplasia.

Musculoskeletal system.

Arthralgia, joint disorder, myalgia.

Nervous system.

Hypaesthesia, dysaesthesia.

Skin and appendages.

Angioedema, maculopapular rash, pustular rash, vesiculobullous rash.

Urogenital system.

Urinary frequency increased.

General disorders and administration site conditions.

Fever.
In dialysis patients with malignant hypertension and hypovolaemia a distinct fall in blood pressure can occur as a result of vasodilation.
The most common adverse effect reported was oedema which was dose related and ranged in frequency from approximately 10% on 30 mg to 30% at the highest dose studied (180 mg). In clinical trials of 20 mg the frequency of peripheral oedema ranged from 0% to 4%.
There have been a small number of reports of chest pain not associated with myocardial infarction occurring soon after administration of a single dose of nifedipine. In such an event, the medicine must be discontinued if a causal relationship is suspected.
Aggravation of cardiac insufficiency has occasionally been reported in patients with compromised cardiac function or when nifedipine is given in combination with beta-blockers.
Rare, usually transient, but occasionally significant elevations of enzymes such as alkaline phosphatase (AP), creatine phosphokinase (CPK), lactate dehydrogenase (LDH), AST (SGOT) and ALT (SGPT) have been noted. The relationship to nifedipine therapy is uncertain in most cases, but probable in some. These laboratory abnormalities have rarely been associated with clinical symptoms, however intrahepatic cholestasis with or without jaundice has been reported. Rare instances of allergic hepatitis have also been reported.
A small (5.4%) increase in mean alkaline phosphatase has been noted in patients treated with controlled release nifedipine tablets. These cases are rare and not associated with clinical symptoms and they rarely result in values outside the normal range.
In controlled studies, controlled release nifedipine tablets did not adversely affect serum uric acid, glucose or cholesterol. Serum potassium was unchanged in patients receiving controlled release nifedipine tablets in the absence of concomitant diuretic therapy and slightly decreased in patients receiving concomitant diuretics.
Nifedipine, like other calcium channel blockers, decreases platelet aggregation in vitro. A limited number of clinical studies have demonstrated a moderate but statistically significant decrease in platelet aggregation in some nifedipine treated patients. This is thought to be a function of inhibition of calcium transport across the platelet membrane. No clinical significance for this finding has been demonstrated.
In a double blind comparison of nifedipine extended release and immediate release tablets, the incidence of vasodilator reactions did not differ.

Postmarketing reports.

A small number of events identified during ongoing post-marketing surveillance associated with nifedipine for which a frequency could not be estimated are listed in Table 1.

Reporting suspected adverse effects.

Reporting suspected adverse reactions after registration of the medicinal product is important. It allows continued monitoring of the benefit-risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions at www.tga.gov.au/reporting-problems.

4.9 Overdose

Symptoms.

The following symptoms are observed in cases of severe nifedipine intoxication: disturbances of consciousness to the point of coma, severe hypotension, tachycardic/bradycardic heart rhythm disturbances, hyperglycaemia, metabolic acidosis, hypoxia, cardiogenic shock with pulmonary oedema.

Treatment.

As far as treatment is concerned, elimination of the poison and the restoration of stable cardiovascular conditions have priority.
After oral ingestion of a potentially dangerous amount, thorough gastric lavage is indicated, particularly in cases of intoxication with controlled release products like APO-Nifedipine XR. Elimination must be as complete as possible, including the irrigation of the small intestine, to prevent the subsequent absorption of the active substance. Symptoms and signs of overdose may be delayed due to the controlled release properties of these products, so patients should be kept under observation for at least 24 hours.
Haemodialysis is ineffective in removing nifedipine from the body because nifedipine is not dialysable (high plasma protein binding), but plasmapheresis may be considered.
Bradycardic heart rhythm disturbances may be treated symptomatically with beta-sympathomimetics and, in life threatening situations, temporary pacemaker therapy may be advisable.
Hypotension as a result of cardiogenic shock and arterial vasodilatation can be treated with calcium (calcium gluconate 10% solution 10 to 20 mL administered slowly intravenously and repeated if necessary). If the effects are inadequate, the treatment can be continued with ECG monitoring, with the addition of a beta-sympathomimetic drug (e.g. isoprenaline 0.2 mg slowly intravenously, repeated if necessary as a continuous infusion at 5 microgram/minute). If this is still insufficient to return the blood pressure to normal, vasoconstricting sympathomimetics such as dopamine or noradrenaline may be additionally administered. The dosage of these drugs is determined solely by the effect obtained.
Additional liquid or volume must be administered with caution because of the danger of overloading the heart.
For information on the management of overdose, contact the Poison Information Centre on 13 11 26 (Australia).

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.

Nifedipine inhibits the transmembrane influx of calcium ions into cardiac and vascular smooth muscle. The contractile processes of these tissues are dependent upon the movement of extracellular calcium into the muscle cells through specific ion channels. Nifedipine selectively inhibits the transmembrane influx of calcium through the slow channel without affecting the transmembrane influx of sodium through the fast channel to any significant degree. This results in a reduction of free calcium ions available within the muscle cells and an inhibition of the contractile process. Nifedipine does not affect total serum calcium. The specific mechanisms by which nifedipine relieves angina and reduces blood pressure have not been fully determined but are believed to be brought about largely by its vasodilatory action.

Hypertension.

The mechanisms by which nifedipine reduces arterial blood pressure involve peripheral arterial vasodilatation and the resulting reduction in peripheral vascular resistance. The increased peripheral resistance that is an underlying cause of hypertension results from an increase in active tension in the vascular smooth muscle. Studies have demonstrated that the increase in active tension reflects an increase in free calcium in the cytosol.
The binding of nifedipine to voltage dependent and possibly receptor operated channels in vascular smooth muscle results in an inhibition of calcium influx through these channels. The reduction in calcium influx by nifedipine causes arterial vasodilatation and decreased peripheral vascular resistance which results in reduced arterial blood pressure.

Angina.

The precise mechanism by which inhibition of calcium influx relieves angina has not been fully determined. Some of the possible mechanisms include vasodilatation and reduction of oxygen utilisation.
Nifedipine dilates the main coronary arteries and coronary arterioles in both normal and ischaemic regions, resulting in an increase in blood flow and hence in myocardial oxygen delivery in patients with coronary artery spasm.
Nifedipine reduces arterial blood pressure at rest and at a given level of exercise by dilating peripheral arterioles and reducing the total peripheral vascular resistance (afterload) against which the heart works. This unloading of the heart reduces myocardial energy consumption and oxygen requirements, and probably accounts for the effectiveness of nifedipine in chronic stable angina.

Clinical trials.

Angina.

The pivotal clinical studies were performed in patients with chronic stable angina. In these studies, nifedipine extended release tablets at doses of 30 and 60 mg once daily improved exercise tolerance test (ETT) parameters in reference to baseline. Nifedipine extended release tablets, 30 mg daily showed a small but suboptimal benefit. When titrated to the dose of 60 mg once daily, the tablets were as effective as atenolol 100 mg once daily. In patients already receiving beta-blocker therapy, nifedipine extended release tablets improved ETT parameters and time to 1 mm ST depression, and at doses of up to 90 mg once daily was more effective than modified release nitrates (isosorbide mononitrate 50 mg once daily or isosorbide dinitrate 20 to 40 mg twice daily). However in this particular study, ETT performance was measured at 22 to 24 hours after the last dose of nifedipine extended release tablets and isosorbide mononitrate, and about 15 hours after the last dose of isosorbide dinitrate. Therefore, the higher efficacy observed for nifedipine extended release tablets may be attributable to the difference in pharmacokinetics to nitrates. In pivotal and supportive clinical studies, the duration of treatment with nifedipine extended release tablets was limited to two to twelve weeks only, and the majority of patients in these studies were already on background beta-blocker therapy. Data in patients with unstable angina, asymptomatic ischaemia, vasospastic angina and postmyocardial infarction are limited. Data on monotherapy with nifedipine extended release tablets are limited and based on trials of short duration (four weeks or less).

5.2 Pharmacokinetic Properties

Absorption.

Nifedipine is almost completely absorbed after oral administration. Plasma drug concentrations rise at a gradual, controlled rate exhibiting zero order absorption kinetics after nifedipine extended release tablet administration and reach a plateau at approximately six hours after the first dose. For subsequent doses, relatively constant plasma concentrations at this plateau are maintained with minimal fluctuations over the 24 hour dosing interval. At steady state, the bioavailability of nifedipine extended release tablets is 86% relative to an immediate release dosage form which has a systemic availability of 45 to 68%. Administration of nifedipine extended release tablets in the presence of food slightly alters the early rate of drug absorption, but does not influence the extent of drug bioavailability. Markedly reduced gastrointestinal retention times over prolonged periods (i.e. short bowel syndrome) may, however, influence the pharmacokinetic profile of the drug, which could result in lower plasma concentrations. The pharmacokinetics of nifedipine extended release tablets are linear over the dose range of 30 to 180 mg, in that plasma concentrations are proportional to dose administered. There is no evidence of dose dumping in either the presence or the absence of food.

Distribution.

Nifedipine is about 95% bound to plasma protein (albumin).

Metabolism.

The active substance nifedipine is almost completely metabolised in the liver, primarily by oxidative processes (the cytochrome P450 enzyme CYP3A4). Some metabolic activity within the gut wall may also contribute to the presystemic metabolism. These metabolites show no pharmacodynamic activity. The main metabolite is the hydroxycarbolic acid derivative (95%); the remaining 5% is the corresponding lactone.

Excretion.

Nifedipine is excreted in the form of its metabolites, predominantly via the kidneys (60 to 80%), and about 5 to 15% is excreted via the bile in the faeces. The unchanged substance is recovered only in traces (below 0.1%) in the urine.
The terminal elimination half-life is 1.7 to 3.4 hours in an immediate release formulation. In cases of impaired kidney function, no substantial changes have been detected in comparison with healthy volunteers.
In cases of impaired liver function, the elimination half-life is distinctly prolonged and the total clearance is reduced. A dose reduction may be necessary in severe cases.
Patients on haemodialysis or chronic ambulatory peritoneal dialysis have not reported significantly altered pharmacokinetics of nifedipine.
Some published studies have reported slower elimination of nifedipine in different ethnic groups (e.g. Mexican, Japanese and South Asian patients). Currently, confirmatory studies only exist for the South Asian population. In comparison to Caucasian patients, there were increases in area under the curve (AUC) due to a decrease in the activity of cytochrome P450 (IIIA), while increases in Cmax were less pronounced. Elimination half-lives of both nifedipine and its pyridine metabolite were prolonged approximately twofold. Although haemodynamic responses in the South Asian healthy volunteers were similar to those reported in Caucasian patients, lower doses of nifedipine may be required in South Asian patients at the beginning of APO-Nifedipine XR therapy.

5.3 Preclinical Safety Data

Genotoxicity.

No data available.

Carcinogenicity.

Nifedipine was administered orally to rats for two years and was not shown to be carcinogenic. In vitro and in vivo mutagenicity studies were negative.

6 Pharmaceutical Particulars

6.1 List of Excipients

APO-Nifedipine XR tablets contain purified talc, povidone, lactose monohydrate, carbomer 934P, hypromellose, colloidal anhydrous silica, magnesium stearate, titanium dioxide, iron oxide red CI77491, macrogol 4000 and Eudragit E100.

6.2 Incompatibilities

Incompatibilities were either not assessed or not identified as part of the registration of this medicine.

6.3 Shelf Life

In Australia, information on the shelf life can be found on the public summary of the Australian Register of Therapeutic Goods (ARTG). The expiry date can be found on the packaging.

6.4 Special Precautions for Storage

Store below 25°C.

6.5 Nature and Contents of Container

APO-Nifedipine XR 30 mg tablets are available in blister pack (PVC/PVDC/Al) of 30 tablets.
APO-Nifedipine XR 60 mg tablets are available in blister pack (PVC/PVDC/Al) of 30 tablets.

6.6 Special Precautions for Disposal

In Australia, any unused medicine or waste material should be disposed of by taking to your local pharmacy.

6.7 Physicochemical Properties

Nifedipine is a yellow, crystalline powder which is practically insoluble in water and sparingly soluble in absolute ethanol. It is sensitive to light.

Chemical structure.

Chemical Name: dimethyl 2,6-dimethyl-4-(2-nitrophenyl)- 1,4-dihydropyridine-3,5-dicarboxylate.
Structural Formula:
Molecular Formula: C17H18N2O6.
Molecular Weight: 346.3.

CAS number.

CAS Registry Number: 21829-25-4.

7 Medicine Schedule (Poisons Standard)

S4: Prescription Only Medicine.

Summary Table of Changes