Sevelamer

Control of Phosphorus Levels

Sevelamer is primarily prescribed for people with chronic kidney disease who are undergoing dialysis. In patients with severe kidney disease, the kidneys are unable to effectively remove phosphorus from the bloodstream. This medication works by binding to the phosphorus found in food during digestion, preventing it from being absorbed into the body.

Conditions Treated

This medication is used to manage:

• Hyperphosphatemia: This is the medical term for abnormally high levels of phosphorus in the blood.
• Complications of Chronic Kidney Disease: By lowering phosphorus levels, sevelamer helps prevent complications such as low calcium levels, bone disease, and the buildup of mineral deposits in the heart, lungs, and blood vessels.

Patient Population

Sevelamer is approved for use in both adults and children who are at least 6 years of age and are receiving dialysis treatment for kidney failure.

How Sevelamer Works

Sevelamer belongs to a class of medications known as phosphate binders. It is used to manage phosphorus levels in people with chronic kidney disease who are on dialysis. When the kidneys are not functioning properly, they cannot effectively remove phosphorus from the blood, which can lead to serious health complications.

The medication works through the following process:

• Binding in the Digestive Tract: Sevelamer is a polymer that is not absorbed by the body. When taken with meals, it stays within the stomach and intestines, where it attaches to the phosphorus found in food.
• Blocking Absorption: By binding to the phosphorus, the medication prevents the mineral from passing through the intestinal walls and entering the bloodstream.
• Elimination: The bound phosphorus remains trapped with the medication and is eventually passed out of the body through bowel movements.

By reducing the amount of phosphorus absorbed from the diet, sevelamer helps maintain a healthier balance of minerals. This process also helps prevent the body from pulling calcium out of the bones and reduces the risk of calcium deposits forming in the heart, lungs, and blood vessels.

Common Side Effects

The most frequently reported side effects of sevelamer involve the digestive system. These may include:

• Nausea and vomiting
• Stomach pain, gas, or bloating
• Diarrhea or constipation
• Indigestion
• Headache
• Cough
• Joint pain
• Feeling tired

Serious Side Effects

While less common, sevelamer can cause serious medical issues. Seek immediate medical attention if you experience:

• Severe constipation or worsening stomach pain
• Difficulty swallowing or the sensation of food getting stuck in the throat
• Black, bloody, or tarry stools
• Signs of an allergic reaction, such as hives, rash, or swelling of the face, lips, or throat
• Severe nausea and vomiting accompanied by fever
• Trouble breathing

Gastrointestinal Conditions

Sevelamer should not be used by individuals with a bowel obstruction. Serious gastrointestinal issues have been reported, including intestinal perforation, bleeding, and obstruction. It should be used with caution in patients with severe constipation, diverticulitis, or those who have had major gastrointestinal surgery. Inflammatory disorders such as colitis or necrosis of the intestine have also occurred.

Patients with swallowing disorders or difficulty swallowing should use caution, as the tablets may pose a choking risk or become stuck in the esophagus.

Vitamin and Mineral Levels

This medication may interfere with the body's ability to absorb fat-soluble vitamins (A, D, E, and K) and folic acid. Healthcare providers may monitor these levels and provide supplements if they become too low. Additionally, blood tests are used to monitor levels of phosphorus, bicarbonate, and chloride to ensure the medication is working safely.

Drug Interactions

Sevelamer can bind to other medications in the digestive tract, making them less effective. Other oral medications are typically taken at least one hour before or three hours after sevelamer. This is particularly important for certain antibiotics, medications for heart rhythm, and thyroid treatments.

Pregnancy

There are no adequate and well-controlled studies of sevelamer use in pregnant women. Because the medication is not absorbed from the digestive tract into the bloodstream, it is not expected to reach the developing fetus directly.

However, sevelamer can bind to and decrease the absorption of certain nutrients that are vital for fetal development, including:

• Folic acid
• Vitamin A
• Vitamin D
• Vitamin E
• Vitamin K

If you are pregnant or planning to become pregnant, discuss the potential risks and benefits of this medication with your healthcare provider. They may monitor your vitamin levels or recommend supplements if sevelamer is necessary for your treatment.

Breastfeeding

It is not known whether sevelamer passes into human breast milk. Because the drug is not absorbed into the mother's systemic circulation, it is unlikely to be present in breast milk or to pose a direct risk to a nursing infant.

As with pregnancy, the primary concern is the medication's potential effect on the mother's vitamin levels. Consult with a healthcare professional to determine if sevelamer is appropriate while breastfeeding and to ensure adequate nutritional intake for both mother and child.

Available Forms

Sevelamer is provided in two chemical formulations: sevelamer carbonate and sevelamer hydrochloride. Both types are intended for oral use and are typically taken with meals.

Sevelamer Carbonate

• Tablets: These are oral tablets that should be swallowed whole and not crushed, chewed, or broken.
• Powder for Oral Suspension: This form comes in individual packets. The powder must be mixed with a specific amount of water and stirred thoroughly before drinking.

Sevelamer Hydrochloride

• Tablets: This formulation is available as oral tablets to be swallowed whole with meals.

FDA Approval and Indications

Sevelamer was first approved by the U.S. Food and Drug Administration (FDA) in 1998 as sevelamer hydrochloride. A second form, sevelamer carbonate, received FDA approval in 2007. It is indicated for the control of serum phosphorus in patients with chronic kidney disease (CKD) who are undergoing dialysis.

Usage in Specific Populations

Sevelamer carbonate is approved for use in both adults and pediatric patients aged 6 years and older. The medication is available by prescription only and comes in several forms, including oral tablets and powder for oral suspension.

Regulatory Safety Information

There are currently no boxed warnings or Risk Evaluation and Mitigation Strategy (REMS) programs required for sevelamer. However, regulatory labeling includes warnings regarding the potential for serious gastrointestinal events. These may include:

• Bowel obstruction or perforation
• Gastrointestinal tract inflammation or ulceration
• Difficulty swallowing tablets

The FDA requires that these risks be documented in the prescribing information, particularly for patients with a history of gastrointestinal disorders or major gastrointestinal surgery.

Generic Availability

Sevelamer is available in generic form as both sevelamer carbonate and sevelamer hydrochloride. Generic versions are generally less expensive than the brand-name medications Renvela and Renagel.

Factors Influencing Cost

The amount you pay for sevelamer can vary based on several factors:

• Insurance Coverage: Most insurance plans, including Medicare Part D, cover sevelamer, but the cost depends on your plan's specific drug tier and copay requirements.
• Formulation: Sevelamer is available as an oral tablet and as a powder for oral suspension. The price may differ between these two forms.
• Pharmacy Pricing: Costs can vary between different retail pharmacies or mail-order services.