Istin is a tablet medication for angina made by Pfizer. It is a calcium-channel blocker, which works by easing blood supply to and from the heart.

Please note that you cannot buy this product from our pharmacy.

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PLEASE NOTE: This treatment is not available through our online pharmacy service. This page is for information only. If you are experiencing any of the symptoms related to the condition(s) this medication treats, we strongly recommend that you see your GP in person.
Product information

Istin is a tablet manufactured by Pfizer, used to treat angina pectoris. The tablet is taken once a day and works by facilitating the flow of blood to the heart, and reducing chest pain. Medicines of this kind are known as calcium-channel blockers. It is also useful at treating hypertension. Before you buy Istin in the UK, you will need a prescription from your doctor.

Angina is a condition characterised by tightness and dull pain in the chest. This discomfort can also sometimes extend to the left arm, the neck, and the jaw. Pain takes on the form of an attack, which, in stable angina, occurs in response to physical strain or stress. Unstable angina cases are less predictable, and attacks may be the result of a less obvious initiating factor.

The condition is more common in people who are aged 55 over. In the UK, angina affects one in twelve men and one in thirty women in their late 50s and early 60s. Lifestyle habits, such as smoking, eating an unhealthy diet, and not getting enough exercise can all contribute to the condition. Symptoms result from the hardening and clogging up of the arteries which supply the heart. This can restrict blood flow and induce a decrease in oxygen supply, causing the heart to strain trying to get the oxygen it requires.

Certain factors, such as having diabetes or high blood pressure, can increase a person’s risk of developing angina, as can having a family history of heart problems. Having a healthy and balanced diet, getting regular exercise, and stopping smoking are all recommended prevention measures.

How angina is treated depends on the severity of the condition. Those who have unstable angina, where attacks may persist even after a period of rest, should seek immediate medical advice. For cases of stable angina, a doctor may issue a prescription treatment to limit the risk of an attack.

The active constituent in Istin is a substance called amlodipine, which is a type of medicine called a calcium antagonist. In reducing the provision of calcium to the arterial muscle walls, amlodipine helps the vessels to relax and widen, and this increases blood flow to and from the heart. As a result, the heart doesn’t have to beat with as much force to get the oxygen it needs. Tightness and pain is then reduced.

If you require angina medication please arrange an appointment with your doctor’s practice. You cannot buy Istin treatment from our pharmacy service.

Page last reviewed:  05/12/2019


Following the instructions issued to you by your doctor is vital when using this or any other treatment. Doing so will help you to eliminate the risk of side effects, and enable the medication to work at it’s most effective. You should also read the patient information leaflet carefully prior to use.

  1. Take as directed.
  2. For angina, this will typically be one 5mg tablet a day to begin with.
  3. Your doctor may choose to increase this to one 10mg tablet a day.
  4. Swallow tablets whole with water.
  5. Do not take with grapefruit juice.
  6. Never take more than the prescribed amount.
  7. If you miss a dose, skip it and take your next one at the scheduled time. Do not make up for a missed dose with a double dose.

The above is only intended as a guide. More detailed instructions can be found in the leaflet supplied.

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Page last reviewed:  05/12/2019
Please read the patient information leaflet for this medicine fully before use:

Istin 5mg

Istin 10mg

Side effects & Warnings

Side effects

If you notice any signs of the following, tell your doctor right away: worsening of angina symptoms; heart attack or irregular heartbeat; an allergic reaction, such as sudden wheeziness, chest pain, shortness of breath, swollen eyelids, tongue, throat, face or lips, skin rash, hives, severe itching, blistering, or peeling; or an inflamed pancreas, such as stomach pain which may reach through to the back.

Very common (1 in 10 people or more):

Ankle swelling.

Common (1 in 10 people or less):

Headache, dizziness, sleepiness, palpitations, flushing, abdominal pain, feeling or being sick, irregular bowel frequency, diarrhoea, constipation, indigestion, tiredness, weakness, sight problems, or muscle cramps.

Uncommon (1 in 100 people or less):

Mood swings, anxiety, depression, sleeplessness, trembling, taste abnormalities, drop in blood pressure, fainting, numbness or tingling sensation in the limbs, loss of pain sensation, tinnitus, inflammation of the lining of the nose, cough, hair loss, dry mouth, increased sweating, itchy skin, red patches on skin, skin discolouration, increased urinary frequency, problems getting or maintaining an erection, joint or muscle pain, back pain or weight fluctuations.

Rare (1 in 1,000 people or less):


Very rare (1 in 10,000 people or less):

Reduction in numbers of white blood cells, decrease in blood platelets which may cause bruising or bleeding, hyperglycaemia, nerve problems, swollen gums, gastritis, liver inflammation, increased muscle tension, photosensitivity, or tremors.

This is not a complete list of the side effects associated with this product. For a more detailed account, please refer to the leaflet provided.

Taking it with other medicines

Let your doctor know if you are taking any other treatments, as they may interact with this product and affect its function. This particularly applies to the following: ketoconazole or itraconazole; ritonavir, indinavir or nelfinavir; rifampicin, erythromycin or clarithromycin; other blood pressure drugs; St John’s wort; verapamil or diltiazem; dantrolene; tacrolimus; simvastatin; or cyclosporine.

Conditions to look out for

Do not use this product if you have: severe low blood pressure; aortic stenosis; cardiogenic shock; or heart failure following a heart attack.

It is also important to let your doctor know if you: have recently had a heart attack; have heart problems of any kind; are hypertensive; have liver disease; or are elderly.

Pregnancy and breastfeeding

Check with your doctor if you are pregnant, breastfeeding or trying to conceive before using this medication.

Driving and using machinery

If you notice any side effects such as dizziness or tiredness, do not drive or try to use machines, and speak to your doctor.

Food and drink

The consumption of grapefruit products should be avoided by those taking Istin, as it may cause levels of the medication in the blood to rise.

Page last reviewed:  05/12/2019
Please read the patient information leaflet for this medicine fully before use:

Istin 5mg

Istin 10mg


Can I still drink alcohol?

It depends on the advice of your doctor. Those who intend to drink alcohol should ask their prescriber before taking this medication.

Will I still be able to drive?

Yes, provided you experience no side effects. However, it will be necessary to see how this drug affects you first before attempting to drive, as it may inhibit your capacity to do so safely. If it does, refrain from driving and speak to your doctor.

Can I take the medicine while pregnant?

This product may not be suitable for those who are pregnant or breastfeeding. Check with your doctor or family planning nurse prior to use.

How should I store it?

Keep the tablets in a safe place below 25°C.

Am I allergic to anything in the medicine?

These tablets contain: amlodipine, calcium hydrogen phosphate anhydrous, magnesium stearate, microcrystalline cellulose and sodium starch glycolate Type A.

Do not take them if you are allergic to any of the above ingredients.

Is it available over-the-counter?

No. Your doctor will need to assess your condition before they issue you with a prescription for this medication.

Is it right for me?

If you think you require treatment for angina you should discuss this with your doctor. If you have angina and are looking to renew your prescription, please speak to your GP surgery.

Page last reviewed:  05/12/2019
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