Generic name: lanthanum carbonate [ LAN-than-um-CAR-bo-nayt ]
Drug class: Phosphate binders

Medically reviewed by Philip Thornton, DipPharm. Last updated on Oct 23, 2023.

What is Fosrenol?

Fosrenol prevents the body from absorbing phosphate, allowing it to be removed from the body.

Fosrenol is used to lower phosphate levels in patients with end stage kidney disease. High levels of phosphate can make it hard for your body to absorb calcium, which can cause serious medical problems.

Fosrenol may also be used for purposes not listed in this medication guide.

Warnings

You should not use Fosrenol if you have a bowel obstruction or severe constipation.

Before you take Fosrenol, tell your doctor if you have a stomach ulcer, ulcerative colitis, Crohn's disease, diabetes, any type of bowel obstruction, or a history of colon cancer or intestinal surgery.

The chewable tablet should be chewed completely before you swallow it.

Take this medicine with food or immediately after eating.

Tell your doctor about all other medicines you use, especially antibiotics, seizure medication, heart or blood pressure medication, or a blood thinner.

If you also take thyroid replacement medication, take it at least 2 hours before or after taking Fosrenol. Do not take thyroid medication and lanthanum carbonate at the same time.

Avoid taking an antacid within 2 hours before or after you take lanthanum carbonate. Some antacids can make it harder for your body to absorb lanthanum carbonate.

Before taking this medicine

You should not use Fosrenol if you are allergic to lanthanum carbonate, or if you have:

• a bowel obstruction or severe constipation.

To make sure Fosrenol is safe for you, tell your doctor if you have ever had:

• a stomach ulcer;

• any type of bowel obstruction;

• slow digestion or severe constipation;

• surgery on your stomach or intestines;

• ulcerative colitis, Crohn's disease, diverticulitis;

• stomach or intestinal cancer; or

• peritonitis (inflammation of the membrane lining the organs inside your abdomen).

If you need to have any type of x-ray or CT scan of your stomach area, tell the doctor ahead of time that you are using Fosrenol.

It is not known whether lanthanum carbonate will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine.

It is not known whether lanthanum carbonate passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breastfeeding.

Related/similar drugs

sucralfate, Carafate, sevelamer, Renvela, Velphoro, Auryxia

How should I take Fosrenol?

Take Fosrenol exactly as prescribed by your doctor. Follow all directions on your prescription label. Your doctor may occasionally change your dose to make sure you get the best results. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Take Fosrenol with food or immediately after eating.

The chewable tablet must be chewed or crushed completely before you swallow it. Do not swallow whole. Tell your doctor if you have trouble chewing the tablet.

Sprinkle the oral powder into a small amount of applesauce or other soft food (oral powder will not dissolve in liquid). Swallow right away without chewing. Do not save the mixture for later use.

While using Fosrenol, you may need frequent blood tests.

Store at room temperature away from moisture and heat.

Dosing information

Usual Adult Dose for Hyperphosphatemia of Renal Failure:

Initial dose: 1500 mg orally daily; take in divided doses with meals
Titrate in increments of 750 mg/day every 2 to 3 weeks until an acceptable serum phosphate level is reached
Maximum dose: 4500 mg/day

Comments: Most patients will require daily doses between 1500 and 3000 mg to reduce plasma phosphate levels to less than 6 mg/dL.

Use: To reduce serum phosphate levels in patients with end stage renal disease.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What to avoid

Fosrenol can make it harder for your body to absorb other medicines you take by mouth.

• If you also take thyroid medication, take it at least 2 hours before or 2 hours after you take Fosrenol.

• If you take an antibiotic such as ciprofloxacin (Cipro) or levofloxacin (Levaquin), take the antibiotic at least 1 hour before or 4 hours after you take lanthanum carbonate.

• Avoid taking an antacid within 2 hours before or 2 hours after you take Fosrenol.

It may be best to avoid taking any other medications by mouth for several hours before or after you take lanthanum carbonate.

Fosrenol side effects

Get emergency medical help if you have signs of an allergic reaction to Fosrenol: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have:

• severe constipation; or

• severe stomach cramps.

Common Fosrenol side effects may include:

• upset stomach, stomach pain, nausea, vomiting;

• constipation;

• itching, rash; or

• tooth injury while chewing the tablet.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What other drugs will affect Fosrenol?

Lanthanum carbonate can make it harder for your body to absorb other medicines you take, which could make the other medicines less effective. If you take any of the following medicines, take them separately from your dose of Fosrenol:

• Thyroid medication: Take it at least 2 hours before or 2 hours after you take lanthanum carbonate.

• An antibiotic such as ciprofloxacin (Cipro) or levofloxacin (Levaquin): Take it at least 1 hour before or 4 hours after you take lanthanum carbonate.

• An antacid: Take it at least 2 hours before or 2 hours after you take lanthanum carbonate.

Other drugs may affect lanthanum carbonate, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Fosrenol only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

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