Lokelma
Potassium Binder for the Treatment of Hyperkalemia
Quick Facts About Lokelma
Key Takeaways About Lokelma
- Treats high potassium effectively: Lokelma selectively binds potassium in the gut and can begin lowering serum potassium levels within 1–2 hours of the first dose
- Two-phase dosing: An initial correction phase (10 g three times daily for up to 3 days) is followed by a once-daily maintenance dose (typically 5 g), making it convenient for long-term use
- Significant sodium content: Each 5 g dose contains approximately 400 mg sodium (20% of the recommended daily maximum), which is important for patients with heart failure or on salt-restricted diets
- Separate from certain other medicines: Some drugs must be taken 2 hours before or after Lokelma to prevent reduced absorption, including tacrolimus, azole antifungals, and HIV medications
- Not for children: Lokelma is approved only for adults; safety and efficacy in children and adolescents under 18 years have not been established
What Is Lokelma and What Is It Used For?
Lokelma (sodium zirconium cyclosilicate) is a potassium binder used to treat hyperkalemia – a potentially dangerous condition where the level of potassium in the blood is too high. It works by trapping potassium in the gastrointestinal tract and removing it from the body through the faeces.
Potassium is an essential mineral that plays a critical role in nerve signalling, muscle contraction, and heart rhythm regulation. Under normal circumstances, the kidneys maintain potassium levels within a narrow range of approximately 3.5–5.0 mmol/L. However, when potassium levels rise above this range (a condition known as hyperkalemia), it can disrupt the electrical activity of the heart and lead to potentially life-threatening cardiac arrhythmias, including ventricular fibrillation and cardiac arrest.
Hyperkalemia is most commonly seen in patients with chronic kidney disease (CKD), where the kidneys’ ability to excrete potassium is impaired. It is also frequently encountered in patients taking medications that affect potassium handling, such as ACE inhibitors (e.g. enalapril, ramipril), angiotensin receptor blockers (ARBs) (e.g. valsartan, losartan), renin inhibitors (e.g. aliskiren), potassium-sparing diuretics (e.g. spironolactone), and mineralocorticoid receptor antagonists. These medications are widely used to treat heart failure and hypertension, and hyperkalemia can be a significant barrier to maintaining them at effective doses.
Lokelma contains sodium zirconium cyclosilicate (SZC), an inorganic, non-polymer crystalline compound with a highly uniform microporous structure. This structure gives it a high selectivity for potassium ions over other cations such as calcium and magnesium. As Lokelma passes through the stomach and intestines, it captures potassium ions in exchange for hydrogen and sodium ions. The bound potassium is then eliminated from the body in the faeces, effectively reducing the total amount of potassium in the body and lowering serum potassium levels.
Clinical trials have demonstrated that Lokelma produces a statistically significant reduction in serum potassium within 1 hour of administration, with normokalemia (normal potassium levels) typically achieved within 24–48 hours. The HARMONIZE trial, a randomised, double-blind, placebo-controlled study, showed that Lokelma maintained normokalemia in 88% of patients at 28 days compared to 46% with placebo. These results have been confirmed in real-world clinical practice and in patients on haemodialysis.
Lokelma was approved by the European Medicines Agency (EMA) in 2018 and by the U.S. Food and Drug Administration (FDA) in 2018 for the treatment of hyperkalemia in adults. It is manufactured by AstraZeneca. Unlike older potassium binders such as sodium polystyrene sulfonate (Kayexalate), Lokelma is highly selective for potassium, has a more predictable onset of action, and has a more favourable gastrointestinal tolerability profile.
What Should You Know Before Taking Lokelma?
Before starting Lokelma, inform your doctor about all your medical conditions, especially heart failure, kidney disease, and any medications you are taking that affect potassium levels. Lokelma is contraindicated only in patients with known hypersensitivity to sodium zirconium cyclosilicate.
Contraindications
You should not take Lokelma if you are allergic (hypersensitive) to sodium zirconium cyclosilicate. Symptoms of an allergic reaction may include skin rash, itching, swelling of the face or throat, or difficulty breathing. If you experience any of these symptoms after taking Lokelma, stop taking it and seek immediate medical attention.
Warnings and Precautions
Talk to your doctor or nurse before taking Lokelma if any of the following apply to you:
- Heart failure: Lokelma can worsen heart failure in some patients. Signs and symptoms of worsening heart failure include increasing shortness of breath, swelling in the legs and ankles, and sudden weight gain. If you experience any of these, contact your doctor immediately. The sodium content of Lokelma may contribute to fluid retention.
- QT prolongation or heart rhythm disorders: Since Lokelma lowers potassium levels, it may affect the electrical signalling of the heart. Tell your doctor if you have a condition that causes QT prolongation or if you are taking any medications known to prolong the QT interval.
- Upcoming X-ray examinations: Lokelma may interfere with the interpretation of certain X-ray results. Inform your radiologist that you are taking this medication.
- Severe or sudden abdominal pain: This may be a sign of a gastrointestinal problem. Seek medical advice promptly.
- Sodium-restricted diet: Each 5 g dose of Lokelma contains approximately 400 mg of sodium (equivalent to 20% of the WHO recommended maximum daily intake). If you have been advised to follow a low-sodium diet, discuss this with your doctor, particularly if you need Lokelma at doses of 5 g or more daily for prolonged periods.
Your doctor will regularly monitor your potassium levels when you start taking Lokelma. This is essential to ensure you receive the correct dose. The dose may be increased or decreased depending on your blood potassium results. If your potassium level drops too low (hypokalemia), your doctor may pause or discontinue the treatment.
Children and Adolescents
Lokelma should not be given to children or adolescents under 18 years of age. This is because the safety and effectiveness of Lokelma in this age group have not been studied. There is currently no clinical data to support its use in paediatric patients.
Pregnancy and Breastfeeding
Pregnancy: There is no clinical data on the use of Lokelma during pregnancy. As a precautionary measure, it is recommended to avoid using Lokelma during pregnancy unless clearly necessary and only after your doctor has carefully weighed the potential benefits against any risks.
Breastfeeding: No effects on breastfed infants are expected because the systemic absorption of Lokelma in the mother is negligible. Sodium zirconium cyclosilicate acts locally in the gastrointestinal tract and does not enter the bloodstream in significant amounts. Therefore, Lokelma can be used during breastfeeding.
Driving and Operating Machinery
Lokelma has no or negligible effect on the ability to drive or use machines. There are no known central nervous system effects associated with this medication.
How Does Lokelma Interact with Other Drugs?
Lokelma can affect the absorption of certain medications in the gastrointestinal tract. Drugs that require an acidic environment for absorption should be taken at least 2 hours before or after Lokelma. Additionally, medicines that alter potassium levels may require dose adjustments when used alongside Lokelma.
Lokelma is not absorbed into the bloodstream and does not undergo hepatic metabolism, which means it does not interact with drugs through the cytochrome P450 enzyme system. However, because Lokelma can temporarily raise gastric pH (make the stomach less acidic), it may reduce the absorption of certain oral medications that depend on an acidic environment for dissolution and absorption. Additionally, Lokelma’s potassium-lowering effect may interact with medications that independently affect potassium levels.
Drugs Requiring Timing Separation
The following medications should be taken at least 2 hours before or after Lokelma to avoid reduced absorption:
| Drug | Category | Reason for Separation |
|---|---|---|
| Tacrolimus | Immunosuppressant | Absorption depends on gastric acidity; reduced levels may lead to transplant rejection |
| Ketoconazole, Itraconazole, Posaconazole | Azole antifungals | Require acidic gastric pH for dissolution and absorption |
| Atazanavir, Nelfinavir, Indinavir, Ritonavir, Saquinavir | HIV protease inhibitors | pH-dependent absorption; reduced levels may compromise viral suppression |
| Raltegravir, Ledipasvir, Rilpivirine | Antiretroviral agents | pH-dependent absorption may be impaired |
| Erlotinib, Dasatinib, Nilotinib | Tyrosine kinase inhibitors (cancer treatment) | Require acidic conditions for solubility and absorption |
Drugs That Affect Potassium Levels
Tell your doctor if you are taking any of the following medications, as your Lokelma dose may need to be adjusted:
| Drug Class | Examples | Effect on Potassium | Clinical Significance |
|---|---|---|---|
| ACE Inhibitors | Enalapril, Ramipril, Lisinopril | Increase potassium | Lokelma dose may need to be higher; monitor K+ levels |
| ARBs | Valsartan, Losartan, Candesartan | Increase potassium | Combined use is common; regular K+ monitoring required |
| Renin Inhibitors | Aliskiren | Increase potassium | Dose adjustment of Lokelma may be needed |
| Potassium-sparing Diuretics | Spironolactone, Eplerenone, Amiloride | Increase potassium | Lokelma enables continued use of these important drugs |
| Loop Diuretics | Furosemide, Bumetanide | Decrease potassium | Combined potassium-lowering effect; risk of hypokalemia |
The ability of Lokelma to manage hyperkalemia is particularly valuable because it allows patients to continue taking RAAS inhibitors (ACE inhibitors, ARBs, and mineralocorticoid receptor antagonists) at optimal doses. These medications have proven cardiovascular and renal benefits, but hyperkalemia often forces dose reduction or discontinuation. By controlling potassium levels, Lokelma helps maintain these essential therapies.
What Is the Correct Dosage of Lokelma?
Lokelma is given in two phases: a correction phase of 10 g three times daily for up to 3 days, followed by a maintenance dose of 5 g once daily. The maintenance dose can be adjusted between 5 g every other day and 10 g once daily. For haemodialysis patients, dosing is different.
Always take Lokelma exactly as your doctor has prescribed. Do not change your dose without consulting your doctor first. Lokelma comes as a powder in sachets that must be mixed with water before drinking.
Correction Phase – Lowering High Potassium
Initial Treatment (Up to 3 Days)
Recommended dose: 10 g taken three times daily
Duration: Maximum 3 days (72 hours)
The correction phase is designed to rapidly bring potassium levels back to the normal range. Most patients achieve normokalemia (potassium 3.5–5.0 mmol/L) within 24–48 hours. Do not continue the correction dose for more than 3 days. Your doctor will monitor your potassium levels during this phase.
Maintenance Phase – Keeping Potassium Normal
Long-Term Treatment
Recommended starting dose: 5 g once daily
Dose range: 5 g every other day to 10 g once daily
Maximum dose: 10 g once daily
After potassium levels have been corrected, your doctor will transition you to a once-daily maintenance dose. The dose will be adjusted based on regular blood tests. If potassium levels remain elevated, the dose may be increased to 10 g once daily. If potassium drops too low, the dose may be reduced to 5 g every other day, or treatment may be paused.
Haemodialysis Patients
Dosing on Non-Dialysis Days Only
Starting dose: 5 g once daily on non-dialysis days
Dose range: 5 g to 15 g once daily
Maximum dose: 15 g once daily
If you are receiving haemodialysis, take Lokelma only on days when you do not have dialysis. Your doctor may increase the dose up to 15 g once daily based on your potassium levels before and after dialysis sessions. Do not take Lokelma on dialysis days.
How to Prepare and Take Lokelma
Follow these steps each time you take Lokelma:
- Open the sachet(s) and pour the powder into a drinking glass containing approximately 45 ml (about 3 tablespoons) of still water. Do not use sparkling or carbonated water.
- Stir well and drink the tasteless liquid immediately. The powder does not dissolve; the liquid will appear cloudy.
- The powder may settle quickly at the bottom of the glass. If this happens, stir again and drink all of the liquid.
- If needed, rinse the glass with a small amount of water and drink it to ensure you consume the full dose.
Try to take Lokelma at the same time each day. It can be taken with or without food.
Missed Dose
If you forget to take a dose of Lokelma, skip the missed dose and take your next dose at the usual time. Do not take a double dose to compensate for a missed one. If you frequently forget your doses, set a daily reminder or associate taking it with a regular daily activity.
Overdose
If you have taken more Lokelma than prescribed, contact your doctor immediately. Do not take any more doses until you have spoken with your doctor. An overdose could cause your potassium levels to drop too low (hypokalemia), which can lead to symptoms such as muscle weakness, fatigue, muscle cramps, abnormal heart rhythms, and in severe cases, paralysis or cardiac arrest. Seek immediate medical attention if you experience severe muscle weakness or heart palpitations after an overdose.
Stopping Lokelma
Do not stop taking Lokelma without consulting your doctor. If you stop taking Lokelma, your potassium levels may rise again to dangerous levels. Your doctor will determine how long you need to continue treatment and will monitor your potassium levels regularly. In some cases, Lokelma may need to be taken on an ongoing basis to maintain normal potassium levels, particularly if you are also taking medications that raise potassium.
What Are the Side Effects of Lokelma?
The most common side effects of Lokelma include worsening of pre-existing heart failure (very common), fluid retention causing swelling (oedema), low potassium levels (hypokalemia), and constipation. Most side effects are manageable with dose adjustment and monitoring.
Like all medicines, Lokelma can cause side effects, although not everybody gets them. Since Lokelma is not absorbed into the bloodstream, its side effects are primarily related to its mechanism of action (potassium lowering and sodium content) and its effects within the gastrointestinal tract.
- Worsening shortness of breath, swelling in the legs and ankles, or sudden weight gain – these may indicate worsening heart failure
- Severe muscle weakness, muscle cramps, or an irregular heartbeat – these may be signs of dangerously low potassium (hypokalemia)
- Sudden or severe abdominal pain – this may indicate a gastrointestinal complication
Very Common
May affect more than 1 in 10 people
- Worsening of pre-existing heart failure (may manifest as increased breathlessness, ankle swelling, and weight gain due to fluid retention)
Common
May affect up to 1 in 10 people
- Hypokalemia (low potassium levels) – may cause tiredness, muscle weakness, or muscle cramps. Tell your doctor immediately if these symptoms become severe
- Oedema (fluid retention) – swelling, particularly in the feet and ankles, due to the sodium content of Lokelma
- Constipation
The sodium content of Lokelma (approximately 400 mg per 5 g dose) is a significant clinical consideration. In patients with heart failure or those on sodium-restricted diets, this additional sodium load can contribute to fluid retention, weight gain, and worsening of heart failure symptoms. Your doctor will carefully weigh the benefits of potassium control against the risks of increased sodium intake.
Your doctor will regularly monitor your serum potassium levels while you are taking Lokelma. If potassium drops below the normal range, your dose may be reduced, or treatment may be temporarily stopped. It is important to attend all scheduled blood tests to allow timely dose adjustments.
If you experience any side effects not listed here, or if any side effect becomes severe, contact your doctor or pharmacist. Reporting suspected side effects helps ensure ongoing monitoring of the medicine’s benefit-risk balance.
How Should You Store Lokelma?
Store Lokelma at room temperature in its original packaging, out of the reach and sight of children. No special storage conditions are required. Do not use after the expiry date printed on the carton or sachet.
Keep Lokelma sachets in their original carton until you are ready to use them. There are no special temperature or humidity requirements for storage. Check the expiry date (marked “EXP” on the carton and sachet) before each use. The expiry date refers to the last day of the stated month.
Do not dispose of unused Lokelma sachets in household waste or down the drain. Return any unused or expired medication to your pharmacy for safe disposal. This protects the environment from pharmaceutical contamination.
What Does Lokelma Contain?
Lokelma contains only one ingredient: sodium zirconium cyclosilicate. There are no additional excipients or inactive ingredients. It is a white to grey powder supplied in individual sachets of 5 g or 10 g.
Active Ingredient
The active substance is sodium zirconium cyclosilicate. Each 5 g sachet contains exactly 5 g of sodium zirconium cyclosilicate. Each 10 g sachet contains exactly 10 g of sodium zirconium cyclosilicate. There are no other ingredients in this medicine – the powder consists solely of the active substance.
Sodium Content
Lokelma contains a clinically significant amount of sodium. Each 5 g dose contains approximately 400 mg of sodium, which is equivalent to 20% of the WHO recommended maximum daily sodium intake for adults (2,000 mg/day). If you are on a sodium-restricted diet, discuss your daily sodium intake with your doctor, particularly if you take Lokelma at doses of 5 g or more per day for extended periods.
Appearance and Packaging
Lokelma is a white to grey powder for oral suspension. It is supplied in individual sachets contained within a cardboard carton. Available pack sizes include cartons of 3 sachets or 30 sachets, in either 5 g or 10 g strengths. Not all pack sizes may be available in your country.
How Does Lokelma Work in the Body?
Lokelma is a non-absorbed, inorganic crystalline compound that acts as a highly selective potassium trap in the gastrointestinal tract. Its uniform microporous structure preferentially captures potassium ions in exchange for hydrogen and sodium ions, with the bound potassium then excreted in the faeces.
Potassium homeostasis is normally maintained by the kidneys, which excrete approximately 90% of ingested potassium. When kidney function declines (as in chronic kidney disease) or when medications impair renal potassium excretion (as with RAAS inhibitors), potassium accumulates in the blood. Lokelma addresses this by providing an alternative route of potassium elimination through the gastrointestinal tract.
Sodium zirconium cyclosilicate is an inorganic zirconium silicate crystal with a well-defined three-dimensional lattice structure containing uniform micropores of approximately 3 Ångströms in diameter. This pore size corresponds closely to the dehydrated ionic radius of the potassium ion (1.33 Å), giving Lokelma a high selectivity for potassium over other physiologically important cations such as calcium (Ca2+) and magnesium (Mg2+). In vitro studies have demonstrated selectivity for potassium that is approximately 25 times greater than for calcium.
As Lokelma passes through the gastrointestinal tract, it captures potassium ions primarily in the large intestine (colon), where potassium concentrations are highest. The exchange involves potassium entering the crystal lattice while hydrogen (H+) and sodium (Na+) ions are released. The potassium-loaded crystal is then excreted in the faeces, effectively removing potassium from the body.
Importantly, Lokelma is not absorbed into the bloodstream. It acts entirely within the gastrointestinal lumen, which limits its systemic side effect profile. However, the sodium released during the ion exchange process is absorbed and contributes to the overall sodium load, which is clinically relevant for patients with heart failure or those on sodium-restricted diets.
Pharmacokinetic Profile
Because sodium zirconium cyclosilicate is not systemically absorbed, traditional pharmacokinetic parameters (such as bioavailability, half-life, and protein binding) do not apply. The onset of potassium-lowering action occurs within 1 hour of the first dose, with clinically meaningful reductions typically achieved within 24–48 hours. The duration of effect is directly related to continued dosing; serum potassium levels will rise again if treatment is discontinued.
Frequently Asked Questions About Lokelma
Lokelma (sodium zirconium cyclosilicate) is used to treat hyperkalemia (high potassium levels in the blood) in adults. It works by selectively binding potassium in the gastrointestinal tract and removing it from the body through the faeces. This helps lower serum potassium to a safe, normal level and reduces the risk of dangerous heart rhythm disturbances.
Lokelma typically begins lowering potassium levels within 1 to 2 hours of the first dose. Clinically meaningful reductions are usually seen within 24 to 48 hours. The initial correction phase uses 10 g three times daily for up to 3 days, after which patients transition to a once-daily maintenance dose of typically 5 g per day.
The most common side effects include worsening of pre-existing heart failure (very common, affecting more than 1 in 10 people), fluid retention causing swelling in the feet and ankles, low potassium levels (hypokalemia causing fatigue and muscle weakness), and constipation. Most side effects are manageable with dose adjustment and regular monitoring.
Yes, Lokelma contains approximately 400 mg of sodium per 5 g dose, which is equivalent to 20% of the recommended maximum daily sodium intake. This is clinically important because excess sodium can contribute to fluid retention and worsen heart failure. Patients on sodium-restricted diets or those with heart failure should discuss this with their doctor, who will weigh the benefits of potassium control against the additional sodium load.
Yes, but certain medications should be taken at least 2 hours before or after Lokelma to avoid reduced absorption. These include tacrolimus (immunosuppressant), azole antifungals (ketoconazole, itraconazole, posaconazole), several HIV medications (atazanavir, ritonavir, and others), and tyrosine kinase inhibitors used in cancer treatment (erlotinib, dasatinib, nilotinib). Always inform your doctor about all medications you are taking.
There is no clinical data on the use of Lokelma during pregnancy, so it should be avoided unless clearly necessary. However, since Lokelma is not absorbed into the bloodstream, no effects on breastfed infants are expected. It can be used during breastfeeding. Always discuss your treatment options with your doctor if you are pregnant, planning to become pregnant, or breastfeeding.
References
This article is based on the following international medical guidelines and peer-reviewed sources. All medical claims have evidence level 1A, the highest quality of evidence based on systematic reviews of randomised controlled trials.
- Packham DK, Rasmussen HS, Lavin PT, et al. Sodium zirconium cyclosilicate in hyperkalemia. New England Journal of Medicine. 2015;372(3):222–231. doi:10.1056/NEJMoa1411487
- Kosiborod M, Rasmussen HS, Lavin P, et al. Effect of sodium zirconium cyclosilicate on potassium lowering for 28 days among outpatients with hyperkalemia: the HARMONIZE randomized clinical trial. JAMA. 2014;312(21):2223–2233. doi:10.1001/jama.2014.15688
- Fishbane S, Ford M, Fukagawa M, et al. A Phase 3b, randomized, double-blind, placebo-controlled study of sodium zirconium cyclosilicate for reducing the incidence of predialysis hyperkalemia. Journal of the American Society of Nephrology. 2019;30(9):1723–1733.
- European Medicines Agency (EMA). Lokelma – Summary of Product Characteristics. EMA product information database. Accessed January 2026.
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Disease: Improving Global Outcomes (KDIGO). Kidney International Supplements. 2024.
- National Institute for Health and Care Excellence (NICE). Sodium zirconium cyclosilicate for treating hyperkalaemia. Technology appraisal guidance [TA599]. 2019.
- World Health Organization (WHO). WHO Model List of Essential Medicines – 23rd list. Geneva: WHO; 2023.
- British National Formulary (BNF). Sodium zirconium cyclosilicate. NICE BNF monograph. Accessed January 2026.
Editorial Team
This article has been written and reviewed by the iMedic Medical Editorial Team, a group of licensed specialist physicians with expertise in nephrology, clinical pharmacology, and internal medicine.
Medical Writers
Board-certified physicians specialising in nephrology and clinical pharmacology with documented academic and clinical experience in electrolyte disorders.
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