Istin

How to order Istin

1. Find the drug you need on our site.
2. Pick a clinic. See the price.
3. Fill in a short health form.
4. A doctor reads your form.
5. If it is safe for you, they say yes.
6. Your order ships fast to your door.
7. It comes in a plain, sealed box.

Why use us? We compare UK clinics. We show you the price and how fast they ship. We do not sell drugs. We just help you find the best one for you.

Is it safe? Yes. All our clinics are UK-based. A real doctor reads each form. They will not sell to you if it is not safe for you.

Istin on Prescriptsy

Istin is described on Prescriptsy as independent product information.

Here you can understand how online consultation works, what medical checks partner clinics carry out, and which factors matter when comparing providers.

We do not sell medicines directly, but help users compare licensed healthcare partners on price, delivery speed, service quality, and overall trustworthiness.

Istin is the brand name for amlodipine besylate tablets, manufactured by Pfizer.

Amlodipine is a dihydropyridine calcium channel blocker used to treat high blood pressure (hypertension) and stable angina pectoris (chest pain caused by reduced blood flow to the heart muscle).

Istin is available as tablets in strengths of 5 mg and 10 mg.

Amlodipine works by relaxing and widening blood vessels, which lowers blood pressure and improves blood flow to the heart.

It has a very long duration of action, allowing once-daily dosing with smooth, consistent blood pressure control.

Amlodipine is also widely available as a generic medicine, and the clinical effects of generic amlodipine are identical to those of Istin.

Hypertension is one of the most common and significant risk factors for cardiovascular disease in the United Kingdom.

The British Heart Foundation estimates that around a third of adults in the UK have high blood pressure, yet many are unaware of their condition because it rarely causes symptoms until damage to the heart, brain, kidneys, or blood vessels has occurred.

Left untreated, sustained hypertension increases the risk of stroke, heart attack, heart failure, chronic kidney disease, peripheral arterial disease, and vascular dementia.

Stable angina, characterised by predictable chest pain or tightness during physical exertion or emotional stress, affects approximately 2 million people in the UK and results from narrowed coronary arteries that cannot supply enough oxygenated blood to meet the heart's demands.

This page provides a comprehensive clinical overview of Istin (amlodipine), covering how it works, who should take it, dosage guidance, potential side effects, important safety warnings, and how to obtain a prescription in the United Kingdom.

Important safety information about Istin (amlodipine)

Before reading further, note these essential safety points about Istin.

• Istin is a prescription-only medicine (POM) and must be used under medical supervision.
• The most common side effect is ankle swelling, which is dose-related and not a sign of heart failure.
• If you take simvastatin, your dose must not exceed 20 mg daily while on amlodipine.
• Amlodipine is not recommended during pregnancy or breastfeeding.
• Do not stop taking Istin without medical advice, even if you feel well.

Understanding hypertension and stable angina

Blood pressure is the force exerted by circulating blood against the arterial walls.

It is measured in millimetres of mercury (mmHg) and expressed as systolic pressure (during heart contraction) over diastolic pressure (during heart relaxation).

NICE guideline NG136 defines hypertension as a clinic reading of 140/90 mmHg or higher, confirmed by ambulatory or home monitoring showing an average of 135/85 mmHg or above.

Hypertension is classified into stages: stage 1 (140/90 to 159/99), stage 2 (160/100 to 179/119), and stage 3 or severe (180/120 or above).

Most people with hypertension have no symptoms. The condition is typically detected during routine health checks.

Once diagnosed, treatment aims to reduce blood pressure to below 140/90 mmHg (or below 130/80 mmHg for patients with diabetes, CKD, or established cardiovascular disease).

Lifestyle modifications are recommended for all patients: reducing salt intake, eating a balanced diet, maintaining a healthy weight, exercising regularly, moderating alcohol, and stopping smoking.

When lifestyle measures alone are insufficient, antihypertensive medication is initiated.

Stable angina occurs when atherosclerotic plaques narrow the coronary arteries, limiting blood flow to the heart muscle during periods of increased demand.

Symptoms typically include chest tightness, heaviness, or pain brought on by exertion and relieved by rest or glyceryl trinitrate (GTN) spray.

Treatment aims to relieve symptoms and reduce cardiovascular risk.

NICE guideline CG126 recommends a beta-blocker or calcium channel blocker as first-line anti-anginal therapy, with the option of combining both if monotherapy is insufficient.

How Istin (amlodipine) works: mechanism of action

Calcium ions are essential for the contraction of smooth muscle cells in arterial walls.

When calcium enters cells through L-type voltage-gated calcium channels, it triggers a cascade that causes muscle contraction and arterial narrowing.

Amlodipine selectively blocks these L-type calcium channels in vascular smooth muscle, preventing calcium entry and allowing the muscle to relax.

This produces dilatation of peripheral arteries and coronary arteries, reducing peripheral vascular resistance and lowering blood pressure.

Amlodipine is classified as a dihydropyridine calcium channel blocker, meaning it acts primarily on blood vessels rather than on the heart's conduction system.

Unlike non-dihydropyridine calcium channel blockers (verapamil and diltiazem), amlodipine has negligible direct effects on the sinoatrial node, atrioventricular node, or myocardial contractility at therapeutic doses.

This vascular selectivity makes it suitable for patients who need blood pressure lowering without the risk of heart rate slowing or conduction disturbances.

In stable angina, amlodipine provides benefit through two mechanisms. First, dilatation of coronary arteries and arterioles increases myocardial oxygen delivery.

Second, reduction of peripheral vascular resistance (afterload) decreases the work the heart must perform, reducing myocardial oxygen consumption.

The net effect is an improved balance between oxygen supply and demand, reducing the frequency and severity of angina episodes.

A defining pharmacokinetic feature of amlodipine is its exceptionally long half-life of 35 to 50 hours, the longest of any commonly prescribed calcium channel blocker.

This produces several clinical advantages: once-daily dosing, gradual onset of action (reducing the risk of reflex tachycardia), smooth 24-hour blood pressure control with minimal peak-to-trough variation, and a forgiving pharmacokinetic profile if a dose is taken late or occasionally missed.

Clinical evidence and UK prescribing guidance

Amlodipine has one of the largest evidence bases of any antihypertensive.

The ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial) compared amlodipine with chlorthalidone and lisinopril in over 33,000 high-risk hypertensive patients and found comparable primary outcomes across all three agents.

The ASCOT-BPLA (Anglo-Scandinavian Cardiac Outcomes Trial, Blood Pressure Lowering Arm) demonstrated that an amlodipine-based regimen was superior to an atenolol-based regimen in reducing cardiovascular events, stroke, and all-cause mortality, and this trial has been influential in shaping UK prescribing guidelines.

The VALUE trial confirmed that amlodipine provides rapid and sustained blood pressure control.

NICE guideline NG136 recommends a calcium channel blocker (amlodipine is the most widely prescribed) as step 1 treatment for hypertension in patients aged 55 and over, patients of Black African or African-Caribbean descent at any age, and as step 2 add-on therapy for patients already taking an ACE inhibitor or ARB.

At step 3, the combination of an ACE inhibitor or ARB, calcium channel blocker, and thiazide-like diuretic is recommended.

The ASCOT trial evidence underpins the recommendation for amlodipine-based regimens in the UK.

For stable angina, NICE CG126 recommends a beta-blocker or calcium channel blocker as first-line monotherapy.

Amlodipine is a suitable calcium channel blocker for this indication, particularly for patients who cannot tolerate or have contraindications to beta-blockers.

The CAPE (Circadian Anti-ischaemia Program in Europe) trial demonstrated that amlodipine significantly reduced episodes of silent and symptomatic myocardial ischaemia.

Istin compared with other calcium channel blockers and antihypertensives

Amlodipine and felodipine are the two most commonly prescribed dihydropyridine calcium channel blockers in UK general practice.

Amlodipine has a longer half-life (35 to 50 hours versus approximately 11 to 16 hours for felodipine modified-release), providing a more forgiving dosing profile and slightly smoother blood pressure control.

Some patients experience more peripheral oedema with amlodipine than with felodipine at comparable blood pressure-lowering doses.

Felodipine requires avoidance of grapefruit juice due to a significant CYP3A4-mediated food-drug interaction; this interaction is clinically less relevant for amlodipine.

Lercanidipine is a newer dihydropyridine with a potentially lower incidence of ankle swelling, though it has a smaller cardiovascular outcome evidence base than amlodipine.

Nifedipine modified-release is an established alternative, particularly favoured in pregnancy-related hypertension where it has a strong safety record.

Non-dihydropyridine calcium channel blockers (verapamil and diltiazem) are used for angina and hypertension but also slow the heart rate and are contraindicated in combination with beta-blockers in most situations. They are not interchangeable with amlodipine.

Other first-line antihypertensive classes include ACE inhibitors (ramipril, lisinopril), ARBs (losartan, candesartan, irbesartan), and thiazide-like diuretics (indapamide, chlorthalidone).

The choice among classes is determined by age, ethnicity, comorbidities, and the NICE stepped-care algorithm.

Many patients require combination therapy with two or three classes to achieve target blood pressure.

Dosage and administration

Istin (amlodipine) is taken as a single daily dose. The recommended starting dose for both hypertension and angina is 5 mg once daily.

If blood pressure or angina symptoms are not adequately controlled after 2 to 4 weeks, the dose may be increased to 10 mg daily.

The maximum recommended dose is 10 mg once daily. Elderly patients and those with hepatic impairment should start at 5 mg and be titrated cautiously.

No dose adjustment is required for renal impairment.

The tablet can be taken at any convenient time of day, with or without food.

Consistency of timing (same time each day) is advisable for routine, though the long half-life means that a few hours' variation has no meaningful effect on blood pressure control.

Do not increase the dose without consulting your prescriber.

If Istin alone does not adequately control your blood pressure, your GP may add another antihypertensive (such as an ACE inhibitor, ARB, or thiazide-like diuretic) rather than exceeding the 10 mg dose.

Side effects of Istin (amlodipine)

Very common and common side effects

Peripheral oedema (ankle swelling) is the most frequently reported side effect, affecting up to 1 in 10 patients at the 5 mg dose and a higher proportion at 10 mg.

It is a pharmacological consequence of arteriolar vasodilatation and is not a sign of fluid overload or heart failure. Diuretics are ineffective.

If oedema is troublesome, your prescriber may reduce the dose, add an ACE inhibitor or ARB (which dilate venules and reduce capillary pressure), or switch to another antihypertensive class.

Headache and flushing are common in the first 1 to 2 weeks and typically diminish with continued use. Dizziness may occur, particularly when standing up quickly. Fatigue, drowsiness, and nausea are also reported by some patients.

Uncommon and rare side effects

Uncommon effects include palpitations, abdominal pain, altered bowel habit, muscle cramps, joint pain, visual disturbance, tinnitus, mood changes, and erectile dysfunction. Gingival hyperplasia (gum overgrowth) may occur with long-term use; regular dental visits and good oral hygiene reduce this risk.

Rare effects include allergic reactions (rash, itching, urticaria), photosensitivity, erythema multiforme, elevated liver enzymes, and very rarely, Stevens-Johnson syndrome, angioedema, gynaecomastia, and hepatitis with jaundice.

When to seek urgent medical advice

Contact your GP or NHS 111 if you experience persistent dizziness, significant ankle swelling that limits daily activities, persistent headache, or gum changes.

Call 999 or attend A&E if you develop severe chest pain, signs of a heart attack (crushing chest pain radiating to arm or jaw, sweating, nausea), signs of a stroke (sudden facial drooping, arm weakness, speech difficulty), severe allergic reaction (swelling of face, lips, tongue, or throat, difficulty breathing), or collapse.

Report any suspected adverse reactions to the MHRA at yellowcard.mhra.gov.uk .

Warnings and precautions

Contraindications

Istin must not be used in patients with known hypersensitivity to amlodipine, other dihydropyridines, or any excipient. It is contraindicated in severe hypotension, cardiogenic shock, clinically significant aortic stenosis, and haemodynamically unstable heart failure following acute myocardial infarction.

Heart failure

Amlodipine may be used in stable heart failure alongside established heart failure treatments, but patients should be monitored for worsening symptoms. The PRAISE trials showed no adverse effect on mortality, but calcium channel blockers are not first-line heart failure therapy.

Hepatic impairment

Amlodipine is extensively hepatically metabolised, and its half-life is prolonged in liver disease. Use the lowest effective dose and monitor for excessive blood pressure lowering.

Simvastatin interaction

Amlodipine increases simvastatin exposure, raising the risk of myopathy and rhabdomyolysis. The simvastatin dose must not exceed 20 mg daily when used with amlodipine.

This interaction does not apply to atorvastatin, rosuvastatin, or pravastatin, which may be used at standard doses.

Pregnancy and breastfeeding

Amlodipine is not recommended during pregnancy. Animal studies have demonstrated reproductive toxicity. Women of childbearing potential should use effective contraception.

If you become pregnant, contact your GP immediately to switch to a pregnancy-safe antihypertensive such as labetalol, methyldopa, or nifedipine modified-release.

Amlodipine passes into breast milk; breastfeeding is not recommended during treatment.

Other drug interactions

CYP3A4 inhibitors (ketoconazole, itraconazole, ritonavir, clarithromycin) may modestly increase amlodipine levels. CYP3A4 inducers (rifampicin, carbamazepine, phenytoin) may reduce levels. Ciclosporin levels may be increased by amlodipine; monitoring is recommended. Tacrolimus levels should also be monitored during concurrent use.

How to get Istin in the UK

Istin (amlodipine) is a prescription-only medicine available through the NHS. Your GP can prescribe it following a clinical assessment of your blood pressure or angina symptoms.

Authorised online prescribers registered with the GPhC can also prescribe it after a suitable clinical consultation.

The NHS prescription charge in England is currently 9.90 pounds per item; prescriptions are free in Scotland, Wales, and Northern Ireland.

Generic amlodipine tablets are widely available and are among the most cost-effective antihypertensive medicines in the UK.

Living with hypertension: lifestyle advice alongside amlodipine

Medication is one part of managing high blood pressure effectively. NICE recommends combining drug treatment with sustained lifestyle modifications for optimal cardiovascular risk reduction.

Reduce your salt intake to less than 6 g per day by choosing fresh foods over processed alternatives and using herbs and spices instead of salt during cooking.

Aim for at least five portions of fruit and vegetables per day.

Maintain a healthy body weight: losing 5 to 10% of body weight if overweight can produce meaningful blood pressure reductions.

Exercise regularly, targeting at least 150 minutes of moderate-intensity activity per week (brisk walking, cycling, swimming).

Limit alcohol to 14 units or fewer per week, spread over at least three days.

Stop smoking: the NHS offers free support through local Stop Smoking services, the NHS Smokefree helpline, and the NHS Quit Smoking app.

If you have angina, carry your GTN spray at all times and know how to use it.

Use one to two puffs under the tongue at the onset of chest pain. If the pain persists after two doses taken five minutes apart, call 999.

Attend regular reviews with your GP or practice nurse to assess blood pressure, symptom control, cardiovascular risk factors, and medication adherence.

Home blood pressure monitoring is encouraged. Use a validated upper-arm monitor, take readings at a consistent time each day (before taking your medication), and record them to review with your GP. Aim for home readings consistently below 135/85 mmHg.

Sources

• Istin 5 mg Tablets, Summary of Product Characteristics (EMC)
• Amlodipine, British National Formulary (BNF)
• NICE NG136: Hypertension in adults: diagnosis and management
• NICE CG126: Stable angina: management
• Amlodipine, NHS medicines information
• High blood pressure (hypertension), NHS
• MHRA Yellow Card Scheme