Lanthanum belongs to the class of medications called phosphate binders. Phosphate is made up mostly of the mineral phosphorus, which is an important part of normal bone structure, cell metabolism, and cell function.

In the body, the kidneys help keep the amount of phosphorus in the blood at a relatively constant level. For people with kidney problems, as their kidney function decreases, less phosphorus is removed from the body, potentially leading to a condition known as hyperphosphatemia (high phosphate levels in the blood). High levels of phosphorus in the blood can lead to problems with the strength and structure of bones. This condition is known as renal osteodystrophy.

When taken with meals, lanthanum prevents the absorption of phosphates from food by binding to the phosphate. It is used specifically to control high levels of phosphate (and therefore phosphorus) in the blood of people who have severe kidney disease, known as end stage renal disease (ESRD), who are receiving dialysis.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The dose of lanthanum depends on the amount of phosphorus that is present in the blood. The usual starting dose ranges from 750 mg to 1500 mg each day, to be taken in divided doses and with or immediately after a meal. Your doctor may adjust the dose every 2 to 3 weeks according to the phosphorus level in your blood. Most people require a dose between 1500 mg to 3000 mg each day.

Chew the tablet completely before swallowing; do not swallow the tablets whole. The tablets may also be crushed.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor.

If you miss a dose, skip the missed dose and continue with your regular dosing schedule at mealtimes. Taking a dose at a time other than mealtime may cause nausea and vomiting. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from moisture, and keep it out of the reach of children.

250 mg
Each chewable, white-to-off-white, round tablet, debossed on one side with "NAT" and "250", contains 250 mg of lanthanum (as lanthanum carbonate dihydrate). Nonmedicinal ingredients: colloidal silicon dioxide, dextrates (hydrated), hydroxy propyl cellulose, magnesium stearate and talc.

500 mg
Each chewable, white-to-off-white, round tablet, debossed on one side with "NAT" and "500", contains 500 mg of lanthanum (as lanthanum carbonate dihydrate). Nonmedicinal ingredients: colloidal silicon dioxide, dextrates (hydrated), hydroxy propyl cellulose, magnesium stearate and talc.

750 mg
Each chewable, white-to-off-white, round tablet, debossed on one side with "NAT" and "750", contains 750 mg of lanthanum (as lanthanum carbonate dihydrate). Nonmedicinal ingredients: colloidal silicon dioxide, dextrates (hydrated), hydroxy propyl cellulose, magnesium stearate and talc.

1000 mg
Each chewable, white-to-off-white, round tablet, debossed on one side with "NAT" and "1000", contains 1000 mg of lanthanum (as lanthanum carbonate dihydrate). Nonmedicinal ingredients: colloidal silicon dioxide, dextrates (hydrated), hydroxy propyl cellulose, magnesium stearate and talc.

Do not take this medication if you:

• are allergic to lanthanum or any ingredients of the medication
• have a blockage in the intestine
• have severe constipation
• have low blood phosphate levels (hypophosphatemia)

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal cramps
• appetite changes
• burping
• constipation
• diarrhea
• gas
• dry mouth
• hair loss
• headache
• heartburn
• increased sweating
• itching
• mouth sores
• nausea
• taste changes
• thirst
• skin rash or redness
• tooth injury
• vomiting
• weight loss

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• allergic skin reaction (rashes, hives, itching)
• broken bones
• chest pain
• infection of the nose, throat, or chest
• loss of height
• low blood pressure (dizziness or lightheadedness, especially when rising from a lying or sitting position)
• muscle or joint pain
• signs of low calcium levels (e.g., confusion, memory loss, numbness, tingling or muscle spasms, weak and brittle nails)
• swelling in your legs and arms

Stop taking the medication and seek immediate medical attention if any of the following occur:

• chest pain
• signs of a serious allergic reaction (shortness of breath or difficulty breathing; hives; swelling of the eyes, mouth, lips, or throat)
• signs of a blockage of the intestines (e.g., abdominal bloating, abdominal pain, swelling, cramps, constipation, vomiting)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take this medication.

Bone conditions: Lanthanum has been shown to accumulate in body tissues and bones. There is limited information to conclude whether or not this medication affects bone quality beyond 2 years of therapy.

Liver disease: The safety and effectiveness of this medication have not been established for people with decreased liver function. If you have reduced liver function or liver disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Stomach problems: Lanthanum may cause very serious bowel obstruction (i.e., blockage). To reduce the risk of bowel obstruction, chew the tablets completely. If you have a history of bowel obstruction, stomach surgery, decreased stomach motility, or constipation, make sure your doctor knows and has taken this into account before you start taking lanthanum. The safety and effectiveness of this medication have not been established for people with acute peptic ulcer, ulcerative colitis or Crohn's disease. If you have these conditions, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

X-rays: Inform your doctor that you are taking lanthanum before having an X-ray of your abdomen, since lanthanum may affect the results.

Pregnancy: The safety and effectiveness of this medication have not been established for pregnant women. Lanthanum is not recommended for use during pregnancy.

Breast-feeding: It is not known if lanthanum passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children and adolescents: The safety and effectiveness of using this medication have not been established for children and adolescents under 18 years of age.

There may be an interaction between lanthanum and any of the following:

• ampicillin
• angiotensin-converting enzyme inhibitors (e.g., lisinopril, perindopril, ramipril)
• antacids (e.g., aluminum hydroxide, magnesium carbonate, magnesium hydroxide, sodium bicarbonate)
• hydroxychloroquine
• ketoconazole
• quinolone antibiotics (e.g., ciprofloxacin, levofloxacin, moxifloxacin)
• statins (e.g., atorvastatin, lovastatin, simvastatin)
• tetracycline antibiotics (e.g., doxycycline, minocycline, tetracycline)
• thyroid medications for an underactive thyroid (e.g., levothyroxine)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.