Rasilez (Aliskiren)

What Is Rasilez and What Is It Used For?

Rasilez belongs to a relatively new class of antihypertensive medications known as direct renin inhibitors (DRIs). It is used to treat essential (primary) hypertension in adult patients aged 18 years and older. Essential hypertension means persistently elevated blood pressure without an identifiable secondary cause, accounting for approximately 90–95% of all hypertension cases worldwide.

Aliskiren, the active substance in Rasilez, was developed by Novartis Pharmaceuticals and represents the culmination of decades of research into renin-system blockade. The European Medicines Agency (EMA) granted marketing authorisation for aliskiren in August 2007, and the U.S. Food and Drug Administration (FDA) approved it in March 2007 under the brand name Tekturna. In many countries outside the United States — including across Europe — it is marketed as Rasilez. Both formulations contain the same active substance and are therapeutically equivalent. In some markets, distribution rights have since been transferred from Novartis to Noden Pharma.

Hypertension is a major modifiable risk factor for cardiovascular disease, chronic kidney disease, and stroke. The World Health Organization (WHO) estimates that hypertension affects approximately 1.28 billion adults worldwide, with fewer than one in five achieving adequate blood pressure control. Left untreated, persistent elevation of blood pressure damages the heart, blood vessels, brain, kidneys, and eyes, and is the leading global cause of premature cardiovascular death. Effective, well-tolerated antihypertensive therapy is therefore fundamental to reducing cardiovascular morbidity and mortality.

Rasilez may be used as monotherapy in patients whose blood pressure is not adequately controlled by lifestyle measures alone, or as part of combination therapy when additional blood pressure reduction is required. It combines effectively with thiazide diuretics, calcium channel blockers, and beta-blockers. However, the use of aliskiren together with an angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) is subject to strict restrictions following the ALTITUDE trial findings, detailed later in this article.

In pivotal clinical trials, Rasilez produced dose-dependent reductions in both systolic and diastolic blood pressure. At the standard 150 mg daily dose, aliskiren lowered systolic blood pressure by approximately 9–11 mmHg and diastolic blood pressure by 8–10 mmHg compared with placebo. Doubling the dose to 300 mg daily produced additional reductions of approximately 3–5 mmHg. The antihypertensive effect is sustained over 24 hours, supporting convenient once-daily dosing, and demonstrates minimal rebound hypertension on discontinuation.

How Does Rasilez Work in the Body?

The renin-angiotensin-aldosterone system (RAAS) is one of the body's most important regulators of blood pressure, fluid balance, and sodium homeostasis. It begins when the kidneys release renin, an enzyme that cleaves angiotensinogen produced by the liver into angiotensin I. Angiotensin I is then converted by angiotensin-converting enzyme (ACE), primarily in the lungs, into angiotensin II — a powerful vasoconstrictor that also stimulates aldosterone release from the adrenal glands, promoting sodium and water retention.

Traditional RAAS-blocking drugs act later in this cascade: ACE inhibitors block the conversion of angiotensin I to angiotensin II, while angiotensin receptor blockers (ARBs) prevent angiotensin II from binding to its type 1 receptor. Aliskiren takes a different approach by blocking the very first and rate-limiting step. By binding directly to the active site of renin, aliskiren prevents renin from cleaving angiotensinogen, thereby reducing the entire downstream production of angiotensin I, angiotensin II, and aldosterone.

A unique pharmacological feature of aliskiren is that it reduces plasma renin activity (PRA), whereas ACE inhibitors and ARBs typically cause a compensatory increase in PRA. Whether the reduction in PRA translates into additional cardiovascular benefit remains controversial and was a major question the ALTITUDE trial sought to answer. The trial’s ultimately disappointing outcome led to a reassessment of the clinical significance of PRA suppression in RAAS blockade.

After oral administration, aliskiren is absorbed with low bioavailability (approximately 2.5%), which is partly due to its active efflux by the P-glycoprotein (P-gp) transporter in the intestinal wall. Peak plasma concentrations are reached within 1 to 3 hours of dosing. Steady state is achieved after 5 to 7 days of once-daily administration. The effective pharmacodynamic half-life is about 40 hours, giving aliskiren excellent 24-hour coverage despite a relatively short elimination half-life in plasma.

Aliskiren is eliminated primarily unchanged in the feces (approximately 78%), with minimal hepatic metabolism. A small fraction (less than 1%) is recovered in the urine, and CYP3A4-mediated metabolism accounts for a minor proportion of drug clearance. Because aliskiren is a P-gp substrate and a weak CYP3A4 substrate, clinically significant drug interactions primarily involve agents that affect these systems — most notably cyclosporine, itraconazole, and certain cardiovascular medications.

What Should You Know Before Taking Rasilez?

Contraindications

There are several situations in which Rasilez must not be used. Regulatory authorities including the EMA and FDA have stipulated the following absolute contraindications based on clinical trial data and post-marketing experience.

Warnings and Precautions

Beyond outright contraindications, several clinical situations require careful consideration before and during treatment with Rasilez. Your prescribing physician will evaluate these risks against the potential benefit of blood pressure reduction.

ALTITUDE trial findings: In 2011, the large ALTITUDE (Aliskiren Trial in Type 2 Diabetes Using Cardiorenal Endpoints) study was terminated early after showing that adding aliskiren to an ACE inhibitor or ARB in high-risk diabetic patients resulted in no cardiovascular or renal benefit, but instead increased the rates of non-fatal stroke, renal complications, hyperkalemia, and hypotension. As a direct consequence, the FDA, EMA, and other regulators added contraindications and stringent warnings against combining aliskiren with ACE inhibitors or ARBs in diabetes and in patients with significant renal impairment. This restriction fundamentally changed how aliskiren is prescribed worldwide.

Hyperkalemia: Like ACE inhibitors and ARBs, aliskiren can raise serum potassium levels because it reduces aldosterone-mediated potassium excretion. The risk is higher in patients with renal impairment, diabetes, or those concurrently taking potassium-sparing diuretics (spironolactone, eplerenone, amiloride), potassium supplements, or salt substitutes containing potassium. Serum potassium should be monitored before starting aliskiren and periodically during therapy, particularly when any of these risk factors are present.

Angioedema: Rare but potentially life-threatening cases of angioedema involving the head, neck, face, extremities, and airway have been reported. Angioedema typically occurs within the first weeks of treatment but can develop at any time. Patients who develop angioedema should discontinue aliskiren immediately and should not receive it again. Emergency airway management may be required if the tongue, glottis, or larynx is involved.

Hypotension: Symptomatic hypotension may occur, particularly in patients with volume or salt depletion (for example, after treatment with high-dose diuretics, severe vomiting, or prolonged diarrhea). Volume depletion should be corrected before starting Rasilez, or treatment should be initiated under close medical supervision. If hypotension occurs, the patient should lie flat, and if necessary, receive intravenous saline. Treatment can usually be resumed once blood pressure has stabilised.

Renal function: Aliskiren can cause deterioration of renal function in patients whose kidney perfusion depends on RAAS activity — for example, those with bilateral renal artery stenosis, severe heart failure, or pre-existing renal impairment. Serum creatinine and potassium should be checked before starting treatment and periodically thereafter. Aliskiren has not been adequately studied in patients with severe renal impairment (eGFR below 30 mL/min/1.73 m²) and should be used with caution.

Heart failure: The efficacy and safety of aliskiren in chronic heart failure have not been established, and use in this setting is not recommended outside of specialist care. The ASTRONAUT and ATMOSPHERE trials did not demonstrate clear benefit of aliskiren in heart failure populations.

Pregnancy and Breastfeeding

Rasilez is strictly contraindicated during pregnancy. Drugs acting directly on the renin-angiotensin system, including ACE inhibitors, ARBs, and direct renin inhibitors, can cause serious fetal and neonatal injury or death when used during the second and third trimesters. Reported effects include fetal renal failure, oligohydramnios (reduced amniotic fluid), pulmonary hypoplasia, skull hypoplasia, limb contractures, and neonatal hypotension. Exposure during the first trimester is also associated with risk of congenital malformations.

Women of childbearing potential should use effective contraception throughout treatment with Rasilez. If pregnancy is diagnosed during therapy, aliskiren should be discontinued immediately and alternative antihypertensive therapy suitable for pregnancy (such as labetalol, methyldopa, or nifedipine) should be initiated. Women planning pregnancy should switch to a pregnancy-appropriate antihypertensive before conception.

It is not known whether aliskiren is excreted in human breast milk. Because of the potential for adverse effects in nursing infants, Rasilez is not recommended during breastfeeding. A decision should be made whether to discontinue breastfeeding or to discontinue aliskiren, taking into account the importance of the medication to the mother.

Children and Adolescents

The safety and efficacy of aliskiren in children and adolescents under 18 years of age have not been adequately established and regulatory authorities have not approved its use in this population. Essential hypertension in children is typically managed with other antihypertensive drug classes that have established pediatric safety profiles.

Elderly Patients

No initial dose adjustment is required for elderly patients (aged 65 years and older). Clinical studies have not identified differences in efficacy between elderly and younger patients. However, the elderly are more likely to have age-related renal impairment and concomitant medications that may increase the risk of hyperkalemia or symptomatic hypotension, so closer monitoring is recommended.

How Does Rasilez Interact with Other Drugs?

Because aliskiren is a substrate of the P-glycoprotein (P-gp) transporter, many of its most clinically important drug interactions involve P-gp modulators. It has minimal hepatic CYP-mediated metabolism, which means classic CYP-based interactions are less prominent than pharmacodynamic interactions (drugs that affect blood pressure, potassium, or renal function).

Major Interactions (Contraindicated or Avoid)

Moderate Interactions (Use with Caution)

Because hypertension is often a lifelong condition, patients typically take Rasilez alongside other medications — for example, statins, aspirin, oral antidiabetic agents, or proton pump inhibitors. Most of these combinations are safe, but a thorough medication review at every office visit or pharmacy pickup is essential to catch new interactions (such as a recently prescribed antifungal or immunosuppressant). Patients should also inform their doctor of any herbal supplements, as St. John's Wort and certain traditional preparations can affect P-glycoprotein activity.

What Is the Correct Dosage of Rasilez?

Adults

Elderly Patients

No specific starting dose adjustment is required for elderly patients. However, older adults are more likely to have age-related reductions in renal function and are at higher risk of orthostatic hypotension. Close monitoring of blood pressure, serum potassium, and serum creatinine is recommended, particularly during dose initiation and titration.

Renal Impairment

For patients with mild-to-moderate renal impairment (eGFR 30–89 mL/min/1.73 m²), no initial dose adjustment is required, but periodic monitoring of renal function and potassium is recommended. Aliskiren has not been adequately studied in patients with eGFR below 30 mL/min/1.73 m² (severe renal impairment) and should be used with caution, or avoided. Remember: combining aliskiren with an ACE inhibitor or ARB is contraindicated in patients with moderate-to-severe renal impairment (eGFR below 60 mL/min/1.73 m²).

Hepatic Impairment

No dose adjustment is required in patients with hepatic impairment, as aliskiren undergoes minimal hepatic metabolism and is primarily excreted unchanged in feces.

Children

Rasilez is not recommended for children or adolescents under 18 years of age. Clinical data in this population are insufficient, and alternative approved antihypertensive agents should be used.

How to Take Rasilez

Swallow the tablet whole with a glass of water. The tablet should not be split, crushed, or chewed. Take Rasilez at approximately the same time each day to maintain steady plasma levels. Because high-fat meals can significantly reduce absorption, choose a consistent dosing routine — either always with a light meal or always between meals. Avoid grapefruit juice and high-fat meals at the time of dosing.

Missed Dose

If you forget to take your daily dose, take it as soon as you remember — unless it is almost time for the next dose, in which case skip the missed dose and continue with your regular schedule. Do not take a double dose to make up for a forgotten one. Consistent daily dosing is particularly important for blood pressure control.

Overdose

The most likely manifestation of aliskiren overdose is symptomatic hypotension, which can be severe. Symptoms include dizziness, lightheadedness, syncope, blurred vision, rapid heartbeat, and fatigue. Management is supportive: the patient should be placed supine with elevated legs, and intravenous saline may be given to restore circulating volume. There is no specific antidote. Hemodialysis is unlikely to remove aliskiren effectively because of its high protein binding and large volume of distribution.

Stopping Treatment

Do not stop taking Rasilez without first consulting your doctor. Hypertension is usually lifelong, and sudden discontinuation may lead to rebound hypertension or poorly controlled blood pressure, increasing cardiovascular risk. Your doctor will advise you on how to transition to alternative therapy if discontinuation becomes necessary.

What Are the Side Effects of Rasilez?

Like all medicines, Rasilez can cause side effects, though not everyone experiences them. Most adverse effects are mild to moderate and resolve with continued treatment or dose adjustment. The side-effect profile of aliskiren differs from that of ACE inhibitors primarily by a lower incidence of cough and by a notable dose-related risk of diarrhea, particularly at the 300 mg dose.

Hyperkalemia warrants specific attention. In clinical trials, serum potassium ≥ 5.5 mmol/L was observed more often in patients on aliskiren than placebo, particularly among those with diabetes, renal impairment, or co-medication with other RAAS blockers or potassium-sparing diuretics. Baseline potassium measurement and periodic monitoring are standard practice. Dietary potassium excess (for example, salt substitutes, large quantities of potassium-rich foods) should also be discussed with your doctor if you have additional risk factors.

If you experience any side effect that concerns you, contact your healthcare provider. You can also report suspected adverse reactions to your national pharmacovigilance authority (for example, the FDA MedWatch programme in the United States or the EMA's EudraVigilance system in Europe). Reporting side effects helps regulators continue monitoring the benefit-risk profile of the medication.

How Should You Store Rasilez?

Proper storage of Rasilez is important to maintain the medication's potency, safety, and intended shelf life. The tablets should be stored below 30°C (86°F) and kept in the original blister pack to protect them from moisture and light. Do not transfer tablets to an unlabelled container (such as a weekly pill organiser) more than a week or two in advance, as this can reduce stability if humidity exposure is significant.

Keep Rasilez out of the sight and reach of children at all times. Children may confuse medication for sweets, and accidental ingestion of even one or two adult tablets can cause significant hypotension in a young child. Consider using a locked cabinet or high shelf for storage, and return medication to its child-resistant packaging after each use.

Do not use Rasilez after the expiration date (EXP) printed on the carton and blister. The expiration date refers to the last day of the indicated month. Using medications past their expiry may result in reduced efficacy and, in rare cases, degradation products that could cause adverse effects.

Do not dispose of medications via wastewater (toilet or sink) or household refuse. Pharmaceutical residues contribute to environmental pollution, including effects on aquatic wildlife. Instead, take expired or unused Rasilez to your local pharmacy or community medicines take-back scheme for safe disposal. Many countries operate nationwide programmes that allow free return of medicines at participating pharmacies.

What Does Rasilez Contain?

Each Rasilez film-coated tablet contains 150 mg of aliskiren (equivalent to 165.75 mg of aliskiren hemifumarate, the salt form used in the formulation). Aliskiren is the pharmacologically active component responsible for direct renin inhibition. A 300 mg strength is also available in many markets.

The inactive ingredients (excipients) that typically make up the tablet core are:

• Crospovidone — a disintegrant that helps the tablet break down after swallowing
• Magnesium stearate — a lubricant that prevents sticking during manufacture
• Microcrystalline cellulose — a binder and bulking agent
• Povidone — a binder that holds tablet ingredients together
• Colloidal anhydrous silica — a flow agent

The film coat (which gives the tablet its characteristic colour and smooth finish, making it easier to swallow) typically contains:

• Hypromellose — the film-forming polymer
• Talc — a glidant
• Macrogol (polyethylene glycol) — a plasticiser
• Titanium dioxide (E171) — a white pigment
• Iron oxides (E172) — red and black pigments used to colour the 150 mg tablet light pink

Rasilez 150 mg tablets are light pink, biconvex, round film-coated tablets typically marked with the manufacturer’s code on one side. They are supplied in PVC/PCTFE–aluminium blister packs of various pack sizes (commonly 14, 28, 30, 56, 84, 90, or 98 tablets), depending on the country of distribution. Not all pack sizes may be marketed in every country.

If you are allergic to any of these ingredients, do not take Rasilez and inform your doctor so that an alternative antihypertensive can be prescribed. Always consult the patient information leaflet supplied with your specific pack, as excipient composition may vary slightly between markets or manufacturers.