Can't Find Sodium Polystyrene Sulfonate? Here Are Your Options

If you've been prescribed Sodium Polystyrene Sulfonate (also called Kayexalate or SPS) for high potassium and your pharmacy can't fill it, you need to know what alternatives exist. Managing hyperkalemia is important — dangerously high potassium can cause life-threatening heart rhythm problems.

The good news is that there are other FDA-approved medications that work in a similar way. Let's walk through what Sodium Polystyrene Sulfonate does, why it might be unavailable, and which alternatives your doctor might recommend.

What Is Sodium Polystyrene Sulfonate?

Sodium Polystyrene Sulfonate is a potassium binder that has been used since 1958. It's a cation-exchange resin — basically, a substance that swaps sodium for potassium in your intestines. The potassium gets trapped and passes out of your body in your stool.

It's available as a powder you mix with water or as a pre-mixed suspension, and it can be taken by mouth or given rectally. Doctors prescribe it most often for people with chronic kidney disease who develop high potassium because their kidneys can't remove it efficiently.

For more details, see our complete guide: What Is Sodium Polystyrene Sulfonate? Uses, Dosage, and What You Need to Know.

How Does Sodium Polystyrene Sulfonate Work?

Once you take Sodium Polystyrene Sulfonate, the resin travels through your digestive tract. Along the way, it releases sodium ions and picks up potassium ions from the lining of your intestines. Each gram of the resin can bind roughly 1 mEq of potassium.

The exchange isn't perfectly selective — the resin can also bind calcium and magnesium, which is why your doctor may monitor these levels. The effect begins within 2 to 24 hours, making it a slower-acting treatment. For emergencies, doctors typically use IV insulin and glucose or IV calcium to stabilize the heart first, then use potassium binders for ongoing management.

Read more about the science: How Does Sodium Polystyrene Sulfonate Work?

Alternatives to Sodium Polystyrene Sulfonate

If Sodium Polystyrene Sulfonate is unavailable or your doctor wants to try a different option, here are the main alternatives for managing high potassium.

1. Patiromer (Veltassa)

What it is: Patiromer, sold under the brand name Veltassa, is a newer potassium binder approved by the FDA in 2015. Unlike Sodium Polystyrene Sulfonate, which exchanges sodium for potassium, Patiromer uses calcium as the exchange ion.

How it works: Patiromer binds potassium in the colon, where most of the drug's potassium-binding activity occurs. It's taken as a powder mixed with water and swallowed — it cannot be heated or mixed with hot liquids.

Pros:

• Generally better tolerated than SPS, with fewer serious GI side effects
• No risk of colonic necrosis (a rare but serious SPS risk)
• Consistent, predictable potassium lowering

Cons:

• More expensive — typically $600 to $900 per month without insurance
• Must separate from other oral medications by at least 3 hours
• May cause constipation, diarrhea, or low magnesium

Best for: Patients who need ongoing potassium management and can't tolerate SPS, or when SPS is unavailable.

2. Sodium Zirconium Cyclosilicate (Lokelma)

What it is: Lokelma is the newest potassium binder on the market, approved by the FDA in 2018. It's a non-polymer compound that works differently from both SPS and Patiromer.

How it works: Lokelma selectively traps potassium ions in the gastrointestinal tract using a crystal structure that mimics the natural ion channels in your body. It has a faster onset of action than SPS — it can start lowering potassium within 1 hour.

Pros:

• Fastest onset of all potassium binders
• Highly selective for potassium (less impact on calcium and magnesium)
• Taken as a tasteless powder mixed with water
• Can be used in both acute and chronic settings

Cons:

• Expensive — approximately $500 to $800 per month without insurance
• Contains sodium, which may be a concern for patients with heart failure or fluid retention
• May cause edema in some patients

Best for: Patients who need rapid potassium lowering or who have had side effects with SPS.

3. Loop Diuretics (e.g., Furosemide)

What they are: Loop diuretics like Furosemide (Lasix) aren't potassium binders, but they can help lower potassium by increasing how much your kidneys excrete in urine.

How they work: These medications block sodium and chloride reabsorption in the kidneys, leading to increased urine output — and increased potassium loss along with it.

Pros:

• Very affordable — generic Furosemide costs as little as $4 to $10
• Widely available
• Also helps with fluid retention

Cons:

• Not a direct potassium binder — works through the kidneys
• Not effective if kidney function is severely impaired
• Can cause dehydration and other electrolyte imbalances

Best for: Patients with mild hyperkalemia who also have fluid retention, used as an add-on treatment.

4. Dietary Potassium Restriction

While not a medication, reducing dietary potassium is an important part of managing hyperkalemia. Your doctor or a dietitian can help you identify high-potassium foods to limit, such as bananas, oranges, potatoes, tomatoes, and spinach. Dietary changes alone aren't usually enough to replace a potassium binder, but they can reduce how much medication you need.

How to Talk to Your Doctor About Switching

If Sodium Polystyrene Sulfonate is unavailable, bring these alternatives up with your doctor. Here are some questions to ask:

• "Would Patiromer or Lokelma be appropriate for my situation?"
• "Will my insurance cover these alternatives?"
• "Are there any patient assistance programs to help with cost?"
• "Can we try the powder form of SPS instead of the suspension?"

Your doctor can help determine which option is best based on your kidney function, other medications, insurance coverage, and how urgently your potassium needs to be managed.

Final Thoughts

Not being able to fill your Sodium Polystyrene Sulfonate prescription is stressful, especially when you know high potassium is dangerous. But you have options. Patiromer (Veltassa) and Sodium Zirconium Cyclosilicate (Lokelma) are effective, FDA-approved alternatives that your doctor can prescribe.

Before switching, try using Medfinder to see if any nearby pharmacies have Sodium Polystyrene Sulfonate in stock — you may find it available at a pharmacy you haven't tried yet. And for the latest on availability, read our 2026 Sodium Polystyrene Sulfonate shortage update.