Rasilez Aliskiren Tablets

IMPORTANT SAFETY INFORMATION: Rasilez (aliskiren) must not be taken in combination with an ACE inhibitor or an ARB in patients who have diabetes or moderate to severe kidney impairment. This combination is contraindicated based on the ALTITUDE trial, which showed an increased risk of serious cardiovascular and renal adverse events. If you are currently taking an ACE inhibitor (such as ramipril or lisinopril) or an ARB (such as losartan, irbesartan, or olmesartan), you must inform your prescriber before starting Rasilez. The prescriber must carefully assess your full medical history and current medicines before any prescription is issued.

Aliskiren works differently from every other antihypertensive medicine currently available in the UK, targeting the renin-angiotensin-aldosterone system at an earlier point in the hormonal cascade than ACE inhibitors or ARBs. Rasilez tablets are a prescription-only direct renin inhibitor containing aliskiren, licensed in adults for the treatment of essential hypertension. As the only medicine of its class approved for hypertension treatment in the UK, Rasilez offers a distinct mechanism of RAAS inhibitor action for patients in whom other antihypertensive medications are not suitable or not sufficient. A prescription can only be issued following a clinical consultation.

Rasilez is a branded prescription medicine manufactured by Noden Pharma. The active ingredient is aliskiren hemifumarate. Aliskiren is a direct renin inhibitor, making it the only medicine in its pharmacological class licensed for the treatment of essential hypertension in the UK. It is available in two strengths: 150 mg and 300 mg film-coated tablets.

Aliskiren acts at the very beginning of the renin-angiotensin-aldosterone system (RAAS), blocking the enzyme renin before it can initiate the hormonal cascade that leads to angiotensin II production and raised blood pressure. This mechanism is distinct from ACE inhibitors (which block the conversion of angiotensin I to angiotensin II) and ARBs (which block the receptor through which angiotensin II acts). Aliskiren targets the system earlier and more completely.

Rasilez is licensed solely for the treatment of essential hypertension in adults. It does not carry additional licensed indications for heart failure or cardiovascular risk reduction. Because of significant safety restrictions introduced following the ALTITUDE trial, Rasilez is generally reserved for patients who have already tried other antihypertensive medicines and in whom a RAAS inhibitor approach remains appropriate. The contraindications relating to combination with ACE inhibitors and ARBs are covered in detail in the side effects and prescribing sections below.

Rasilez lowers blood pressure by directly inhibiting renin, the enzyme that initiates the renin-angiotensin-aldosterone system.

The Renin-Angiotensin-Aldosterone System

The renin-angiotensin-aldosterone system (RAAS) regulates blood pressure and fluid balance through a hormonal cascade. Renin, released by the kidneys in response to low blood pressure or low sodium, is the first enzyme in this cascade. Renin converts angiotensinogen to angiotensin I. ACE then converts angiotensin I to angiotensin II. Angiotensin II causes blood vessels to narrow, stimulates aldosterone release (which promotes sodium and water retention), and raises blood pressure. ACE inhibitors block the second step; ARBs block angiotensin II at its receptor. Aliskiren blocks the first step.

Direct Renin Inhibition

Aliskiren binds directly to renin and prevents it from converting angiotensinogen to angiotensin I. Without this first step, the entire downstream cascade — including angiotensin I, angiotensin II, and aldosterone production — is suppressed. Blood vessels remain relaxed, sodium retention is reduced, and blood pressure falls. Because aliskiren targets renin directly, it also reduces plasma renin activity, a marker of RAAS activation. This upstream inhibition distinguishes aliskiren mechanistically from all other RAAS inhibitors on the market.

One practical consequence of blocking renin at the earliest point is that aliskiren causes a compensatory rise in plasma renin concentration (the kidneys produce more renin in response to its inhibition). This does not reduce the clinical effect of aliskiren but is a pharmacological characteristic relevant to laboratory interpretation. Your prescriber and pharmacist are aware of this when monitoring treatment.

Always take Rasilez exactly as your prescriber instructs. The information below summarises key points from the current UK SmPC. Read the Patient Information Leaflet supplied with your medicine before starting treatment.

• Take one tablet once daily, at approximately the same time each day.
• Rasilez should be taken with a light meal or consistently either with or without food. Taking it with a high fat meal significantly reduces its absorption. The SmPC recommends establishing a consistent routine, take it with the same type of meal or snack each day.
• Swallow the tablet whole with a glass of water. Do not crush or chew the tablet.
• If you miss a dose, take it as soon as you remember on the same day. If you only remember the following day, skip the missed dose and continue as normal. Do not take two doses on the same day.
• Do not stop taking Rasilez without speaking to your prescriber first. High blood pressure requires ongoing management.
• Your prescriber will typically start you at 150 mg once daily and review your blood pressure after two to four weeks. Kidney function and potassium levels may be checked periodically during treatment, as with all RAAS inhibitors. Attend all follow up appointments to allow safe and effective dose review.

Rasilez is available in two strengths. All dose decisions are made by your prescriber.

Rasilez 150 mg Tablets

The 150 mg tablet is the recommended starting dose for essential hypertension. The SmPC advises starting at 150 mg once daily. This dose is effective for many patients and allows your prescriber to assess blood pressure response and tolerability before any increase. In patients aged 65 and over, the 150 mg dose is generally recommended as the maintenance dose, as there is limited evidence for greater benefit from the higher dose in this age group.

Rasilez 300 mg Tablets

The 300 mg tablet is the maximum recommended dose. If blood pressure is not adequately controlled after two to four weeks on 150 mg, the dose may be increased to 300 mg once daily. The 300 mg dose provides additional blood pressure lowering compared to 150 mg. All dose adjustments are made by your prescriber. Do not change your dose without medical advice.

Like all medicines, Rasilez can cause side effects. The information below is based on the current UK SmPC. Refer to the Patient Information Leaflet for the full list.

Common Side Effects (may affect up to 1 in 10 people)

• Diarrhoea. This is the most commonly reported side effect of aliskiren and is more frequent at higher doses. If diarrhoea is severe or persistent, contact your prescriber.
• Dizziness, particularly on standing up quickly
• Raised blood potassium (hyperkalaemia). Blood tests help to detect and manage this.
• Changes in kidney function

Uncommon Side Effects (may affect up to 1 in 100 people)

• Low blood pressure (hypotension), particularly in patients who are volume depleted or also taking diuretics
• Headache
• Fatigue
• Skin rash or itching

Important: ALTITUDE Trial and Dual RAAS Blockade

The ALTITUDE trial investigated whether adding aliskiren to an ACE inhibitor or ARB would provide additional cardiovascular benefit in patients with type 2 diabetes and kidney or cardiovascular disease. The trial was stopped early because the aliskiren combination arm showed a significantly higher rate of serious adverse events compared to placebo. These included non-fatal stroke, kidney complications, raised potassium levels, and low blood pressure.

As a result of the ALTITUDE trial findings, the current UK SmPC for Rasilez carries the following contraindications and restrictions. Aliskiren must not be combined with an ACE inhibitor or an ARB in patients with diabetes or moderate to severe kidney impairment. The combination of aliskiren with an ACE inhibitor or ARB is also not recommended in any patient and should be avoided where possible. This applies to all patients taking Rasilez, not only those with diabetes or kidney disease.

Serious Side Effects: Seek Urgent Medical Attention

Go to your nearest accident and emergency department or call 999 immediately if you experience:

• Angioedema: sudden swelling of the face, lips, tongue, or throat. This is rare but potentially life threatening. Seek emergency help immediately.
• Signs of severely raised potassium such as muscle weakness, an irregular heartbeat, or confusion
• A marked reduction in urine output, which may indicate serious kidney impairment

Report any suspected side effect to your prescriber, pharmacist, or via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk.

Rasilez May Be Suitable If You:

• Are an adult with a confirmed diagnosis of essential hypertension
• Have not achieved adequate blood pressure control with other antihypertensive medicines
• Are not taking an ACE inhibitor or ARB (or your prescriber has carefully assessed that aliskiren is appropriate alongside your current treatment, noting the restrictions below)
• Are already prescribed Rasilez and require a repeat prescription through an online prescribing service

Rasilez Is Contraindicated or Not Recommended If You:

• Have diabetes and are also taking an ACE inhibitor or ARB. This combination is contraindicated per the current SmPC following the ALTITUDE trial.
• Have moderate to severe kidney impairment and are also taking an ACE inhibitor or ARB. This combination is contraindicated per the current SmPC.
• Are taking an ACE inhibitor or ARB without diabetes or kidney impairment. Dual RAAS blockade is still not recommended in this group and should be avoided.
• Are pregnant or planning to become pregnant. Rasilez is contraindicated in pregnancy. Direct renin inhibitors, like ACE inhibitors and ARBs, cause serious harm to the developing baby. Contact your prescriber immediately if you become pregnant while taking Rasilez.
• Are breastfeeding
• Have severe kidney impairment, nephrotic syndrome, or renovascular hypertension (narrowing of the arteries supplying the kidneys)
• Have severe liver impairment
• Have a known allergy or hypersensitivity to aliskiren or any excipient listed in the SmPC
• Are under 18 years of age

Tell your prescriber about all medicines you take. Key interactions for Rasilez include:

• ACE inhibitors and ARBs: the combination of aliskiren with an ACE inhibitor or ARB is contraindicated in patients with diabetes or renal impairment, and not recommended in any patient. If you are taking any ACE inhibitor (such as ramipril, lisinopril, perindopril) or any ARB (such as losartan, irbesartan, olmesartan, telmisartan, valsartan), you must discuss this with your prescriber before starting Rasilez.
• Cyclosporin and itraconazole: these medicines significantly increase aliskiren blood levels. The SmPC advises that Rasilez should not be used with ciclosporin or itraconazole.
• Potassium supplements, potassium-sparing diuretics (such as spironolactone or amiloride), and potassium-containing salt substitutes: these increase the risk of raised blood potassium when combined with aliskiren.
• NSAIDs such as ibuprofen: regular use can reduce the blood pressure lowering effect of Rasilez and increase the risk of kidney problems.
• Furosemide: aliskiren reduces the blood levels of furosemide by approximately 50 per cent. This interaction requires clinical awareness if both medicines are prescribed.

Your prescriber will review all current medicines during the clinical assessment before any prescription is considered.

Rasilez is a Prescription Only Medicine. The clinical consultation is the essential first step. A prescription will only be issued if a registered prescriber concludes, based on their individual assessment of your circumstances, that Rasilez is clinically appropriate for you.

During your online consultation with Pharmacy Planet, a registered prescriber will review the information you provide. This includes your blood pressure history, current antihypertensive medicines, diabetes status, kidney function where available, and other relevant medical information. Given the significant contraindications relating to combination with ACE inhibitors and ARBs, the prescriber will carefully assess your complete medicines list before making any prescribing decision.

If you are under the care of your GP or a specialist for hypertension or a related condition, please keep them informed of all medicines prescribed through online services. Coordinated care is particularly important with Rasilez given the need to avoid dangerous drug combinations within the RAAS inhibitor class.

• Store below 30°C.
• Store in the original packaging to protect from moisture.
• Keep out of the sight and reach of children.
• Do not use after the expiry date printed on the packaging.
• Do not dispose of medicines via household waste or wastewater. Return unused or out of date tablets to your pharmacist for safe disposal.
• Full storage instructions are provided in the Patient Information Leaflet supplied with your medicine.

The table below compares ARB tablets and Rasilez (aliskiren), the only direct renin inhibitor licensed for hypertension in the UK. All act on the renin-angiotensin-aldosterone system (RAAS) and are taken once daily as tablets.

Important: This comparison is for general information only and does not replace medical advice. A prescriber will decide which treatment is suitable for you following an online consultation.

Pharmacy Planet is a GPhC-registered online pharmacy providing access to prescription medicines through a clinically led consultation process. Our registered prescribers and pharmacists are committed to patient safety, clinical accuracy, and responsible prescribing.

We follow GPhC standards, MHRA guidance, and ASA advertising regulations in all aspects of our service. For medicines with significant safety restrictions such as Rasilez, our prescribers exercise particular care to ensure that any prescription issued reflects a thorough clinical assessment and takes into account the current SmPC contraindications. Every prescription is reviewed and dispensed by qualified healthcare professionals.

If you have questions about Rasilez, aliskiren, blood pressure control, or any other aspect of your cardiovascular therapy, our pharmacy team is available to help. We are committed to transparent, patient centred care.

References

1. Electronic Medicines Compendium (eMC). Rasilez 150 mg and 300 mg film-coated tablets — Summary of Product Characteristics. https://www.medicines.org.uk/emc. Accessed May 2026.
2. National Institute for Health and Care Excellence (NICE). Hypertension in adults: diagnosis and management. NICE guideline NG136. https://www.nice.org.uk/guidance/ng136. Accessed May 2026.
3. NHS. High blood pressure (hypertension). https://www.nhs.uk/conditions/high-blood-pressure-hypertension. Accessed May 2026.
4. Joint Formulary Committee. British National Formulary (BNF). Aliskiren. BMJ Group and Pharmaceutical Press. https://bnf.nice.org.uk. Accessed May 2026.
5. European Medicines Agency (EMA). Rasilez/Rasilez HCT — EPAR: Procedure for restriction of use following the ALTITUDE trial. https://www.ema.europa.eu. Accessed May 2026.
6. Medicines and Healthcare products Regulatory Agency (MHRA). Yellow Card — report a side effect. https://yellowcard.mhra.gov.uk. Accessed May 2026.