Auryxia (Ferric Citrate) - Oral

What Is Auryxia?

Auryxia (ferric citrate) is a type of drug called a phosphate binder that helps control phosphorus levels in people with chronic kidney disease (CKD) who are on dialysis. It can also increase iron levels in the blood, which helps treat iron-deficiency anemia in people with severe CKD.

Auryxis works by binding to phosphorus in the foods you eat so that it can be removed from the body in the stool rather than being absorbed in your digestive tract.

This medication is available as an oral tablet for adults only. There are currently no generic alternatives for Auryxia.

What Is Auryxia Used For?

Auryxia is a prescription drug used in adults with severe CKD. The Food and Drug Administration (FDA) has licensed Auryxia for two specific uses:

• To control serum (blood) phosphorus levels in people with CKD on dialysis
• To treat iron deficiency anemia in people with CKD who are not on dialysis

As your kidneys begin to fail, they are less able to remove excess phosphorus from the blood. While a low-phosphorus diet can help, diet alone cannot keep your levels within the normal range if you are on dialysis.

Without phosphate binders like Auryxia, you are at risk of a potentially dangerous condition known as hyperphosphatemia, in which excessively high phosphorus causes the body to draw calcium out of bones, making them weak. This, in turn, can lead to dangerous deposits of calcium in the heart, blood vessels, and other organs and increase the risk of heart attack, stroke, and death. Most cases of hyperphosphatemia are asymptomatic until the downstream effects, like weak bones and calcium deposits, are noticed.

CKD is also associated with iron deficiency, in part because the kidneys are less able to filter a hormone called hepcidin that regulates iron absorption. When hepcidin levels are too high, iron levels plummet, leading to iron deficiency anemia. Iron supplements are the first-line defense against this form of anemia.

Iron also plays a role in the production of erythropoietin (EPO), a hormone produced by the kidneys that tell bone marrow when to make red blood cells. Supplementing iron can help improve EPO production.

How to Take Auryxia

Auryxia is available as a 210-milligram (mg) oral tablet. It is taken by mouth, usually three times daily with meals.

Try not to chew or crush the tablets, as this can cause discoloring of your mouth or teeth.

Storage

Each bottle of Auryxia contains 200 tablets. The tablets do not require refrigeration and can be safely stored at room temperature (between 60 and 77 degrees F). Keep the tablets tightly sealed in their original container to protect them from moisture.

Off-Label Uses

Healthcare providers can prescribe Auryxia for medical conditions not listed on the product label. This is called off-label use. 

Although not formally approved for such use, Auryxia has been used off-label to treat severe iron-deficiency anemia unrelated to CKD. Some healthcare providers will prescribe a short course of treatment, dosed at three to five tablets once a day with a meal.

What Are the Side Effects of Auryxia?

If you are prescribed Auryxia, your kidneys are not functioning well, and you need the drug to avoid potentially serious illness. Let your healthcare provider know if you are experiencing side effects that worsen or don’t go away.

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at fda.gov/medwatch or 1-800-FDA-1088.

Common Side Effects

Auryxia is generally well tolerated but can cause side effects in some people. The most common include (by order of frequency):

• Discolored or blackened stools (a harmless condition caused by the oxidation of unabsorbed iron)
• Diarrhea
• Constipation
• Nausea
• Abdominal pain

Side effects tend to be mild but can become severe. Diarrhea is the most common reason for users stopping their treatment.

If side effects persist or worsen, let your healthcare provider know. Never stop treatment or adjust the dose without speaking with a healthcare provider first.

Severe Side Effects

Auryxia differs from other iron supplements, like ferrous sulfate, in that the gut breaks it down slowly and absorbs it slowly. Because less iron is “lost” as it passes through the intestines, iron levels are increased more efficiently.

With that said, serum iron levels can become excessive and lead to hemochromatosis, also known as iron overload. Your healthcare provider may closely monitor your serum iron levels.

Iron overload occurs when iron begins to accumulate to toxic levels in tissues of the body rather than being excreted in urine and feces. This includes tissues of the heart, lung, brain, liver, spleen, bone marrow, and endocrine organs (organs that produce hormones).

If left untreated, iron overload can lead to sexual dysfunction, arthritis, diabetes, cirrhosis (liver scarring), liver failure, heart failure, and even death.

Call your healthcare provider right away if you have serious side effects after using Auryxia. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. These include symptoms of hemochromatosis, such as:

• Fatigue and weakness
• Joint pain
• “Iron fist” (pain in the joints of the pointer and middle fingers)
• Abdominal pain
• Abdominal swelling
• Darkened, discolored skin
• Abnormal heart rhythms
• Hyperkalemia (elevated potassium)

Long-Term Side Effects

The long-term safety of Auryxia has not been established. There is a concern, however, that long-term use may increase the risk of hemochromatosis in some people.

An 80-week study from Japan, involving 136 adults with CKD on ferric citrate, found that the risk of iron overload was higher in people on peritoneal dialysis (which uses the lining of the abdominal cavity to filter waste) than those on hemodialysis (which directly filters the blood).

Study results have not been consistent. Studies investigating other types of iron-based phosphate binders could find no evidence of an increased risk of iron overload after one year.

Dosage: How Much Auryxia Should I Take?

Modifications

There are no dose modifications for people starting Auryxia. With that said, your healthcare provider may increase your dose incrementally once treatment is started until the desired phosphorus or iron level is achieved.

Your healthcare provider may also adjust the dose if your phosphorus or iron levels get too high.

Missed Dose

If you miss a dose of Auryxia, take it as soon as you remember with food. If it is near the time of your next dose, skip the original dose and continue as per the prescribed schedule. Do not double up doses.

Overdose: What Happens If I Take Too Much Auryxia?

Although there are few reports of Auryxia overdose in the medical literature, the intentional overdose of any iron supplement can cause severe and potentially life-threatening complications. These include severe gastrointestinal bleeding, liver failure, multi-organ failure, and death.

An overdose of iron in pregnant people can potentially increase the risk of miscarriage, gestational diabetes, and fetal birth defects.

Children are at an especially high risk of iron poisoning. It is important, therefore, to keep Auryxia out of the reach of children and to seek immediate emergency care if an accidental overdose occurs.

Iron poisoning is typically treated with whole bowel irrigation. This involves a special solution (usually polyethylene glycol-electrolyte) that is either taken by mouth or fed into the stomach through a nasogastric tube. This helps flush out the excess iron in a rush of diarrhea.

In severe cases, a chelating agent may be delivered intravenously (into a vein) which binds to iron so that it can pass out of the body in urine.

Precautions

What Are Reasons I Shouldn't Take Auryxia?

Auryxia is not used in people with hemochromatosis.

This medication is only intended for adults. Its safety and effectiveness have not been established in children.

The safety of Auryxia in pregnant or breastfeeding people is also unknown. Studies in rats have suggested a risk of birth defects if the drug is delivered intraperitoneally (directly into the stomach) but not if it is taken by mouth. If you are pregnant, planning to get pregnant, or breastfeeding, speak with your healthcare provider to fully understand the benefits and risks of treatment.

What Other Medications Interact With Auryxia?

There are few notable drug interactions with Auryxia. Certain antibiotics may interfere with the absorption of Auryxia. You may need to separate the doses by a few hours to prevent these interactions. 

The two antibiotics of particular concern are:

• Doxycycline (marketed under the brand names Doryx, Monodox, Vibramycin, and others): Take at least one hour before Auryxia.
• Ciprofloxacin (marketed under the brand names Cipro, ProQuin, and others): Take at least two hours before Auryxia.

Use Auryxia with caution if you are being treated with intravenous iron for anemia. Taking both forms of iron can increase the risk of hemochromatosis.

To avoid interactions, always tell your healthcare provider about any drugs you take, whether they are prescription, over-the-counter, herbal, nutritional, or recreational.

What Medications Are Similar?

Iron-based phosphate binders like Auryxia represent a newer form of phosphate binder used in people with CKD.

Traditional calcium- and aluminum-based binders have been around for years and have their proven benefits, but also have limitations. Calcium-based binders may increase the risk of calcification (hardened calcium deposits) in blood vessels. Aluminum-based binders are considered second-line options to calcium-based binders as they are linked to a significant risk of aluminum overload.

In addition to Auryxia, The FDA approved the phosphate binder Velphoro (sucroferric oxyhydroxide) to treat hyperphosphatemia in people with CKD. The FDA is currently evaluating another iron-based phosphate binder called Fermagate (iron-magnesium hydroxycarbonate).

How Can I Stay Healthy While Taking Auryxia?

Living with advanced CKD can be challenging and sometimes overwhelming, particularly since there are things you can control and others you can’t. One of the things you can control is diet. This includes getting the right amount of protein each day while limiting your intake of salt, fluids, potassium, and phosphorus.

To reap the optimal benefits of CKD treatment, it’s important to work with your healthcare provider and registered dietitian if your kidneys are failing. They can help guide your daily food choices and ensure that you get ample nutrition and calories to keep you well.

When it comes to phosphorus, that means knowing how much milk and dairy you can consume and avoiding high-phosphorus foods like bran, nuts, peanut butter, seeds, beans, cola, organ meats, and fish like sardines and mackerel.

Try not to skip any meals, especially if you are on medications like Auryxia that require food. Try spacing your meals out so that your three daily doses are about six to eight hours apart. If you do not feel very hungry, try eating smaller meals throughout the day (while keeping to your dosing schedule).

By doing your part and working with your healthcare team, you can stay healthier at whatever stage of kidney disease you have.