Calcium Carbonate vs. Sevelamer

Attribute	Calcium Carbonate	Sevelamer
Chemical Formula	CaCO3	(C3H7NO)n
Class	Mineral supplement	Phosphate binder
Usage	Used to treat calcium deficiency	Used to lower phosphate levels in patients with kidney disease
Side Effects	Constipation, gas, bloating	Nausea, vomiting, diarrhea

Introduction

Calcium carbonate and sevelamer are two commonly used medications for the treatment of high phosphate levels in the blood, a condition known as hyperphosphatemia. Both medications work by binding to phosphate in the gastrointestinal tract, preventing its absorption into the bloodstream. However, there are some key differences between the two drugs in terms of their chemical composition, side effects, and effectiveness.

Chemical Composition

Calcium carbonate is a calcium salt of carbonic acid, with the chemical formula CaCO3. It is commonly used as a dietary supplement to provide calcium to the body and is also used as an antacid to treat heartburn and indigestion. Sevelamer, on the other hand, is a non-calcium, non-metal containing phosphate binder. It is a polymer that binds to phosphate in the gut, preventing its absorption into the bloodstream. Sevelamer is available in two forms: sevelamer hydrochloride and sevelamer carbonate.

Side Effects

One of the main differences between calcium carbonate and sevelamer is their side effect profiles. Calcium carbonate can cause constipation, gas, and bloating in some patients, especially when taken in high doses. It can also lead to hypercalcemia, or high levels of calcium in the blood, which can be dangerous. Sevelamer, on the other hand, is generally well-tolerated and has fewer gastrointestinal side effects compared to calcium carbonate. However, some patients may experience nausea, vomiting, or diarrhea while taking sevelamer.

Effectiveness

Both calcium carbonate and sevelamer are effective in lowering phosphate levels in the blood. However, studies have shown that sevelamer may be more effective than calcium carbonate in certain patient populations, such as those with chronic kidney disease. Sevelamer has been shown to lower phosphate levels more consistently and effectively than calcium carbonate in these patients. Additionally, sevelamer has been associated with a lower risk of cardiovascular events compared to calcium carbonate.

Dosing and Administration

Calcium carbonate is typically taken with meals to help bind to phosphate in the gut. The dose of calcium carbonate is based on the amount of elemental calcium it contains, with doses ranging from 500 mg to 1,500 mg per day. Sevelamer, on the other hand, is usually taken with meals as well, but the dose is based on the patient's phosphate levels. The starting dose of sevelamer is usually 800-1600 mg per day, with adjustments made based on the patient's response.

Cost

Another important factor to consider when comparing calcium carbonate and sevelamer is the cost. Calcium carbonate is generally less expensive than sevelamer, making it a more cost-effective option for some patients. However, sevelamer may be covered by insurance or Medicare, reducing the out-of-pocket cost for patients. It is important to consider the cost of both medications when making a decision about which one to use for the treatment of hyperphosphatemia.

Conclusion

In conclusion, both calcium carbonate and sevelamer are effective medications for the treatment of hyperphosphatemia. However, there are some key differences between the two drugs in terms of their chemical composition, side effects, effectiveness, dosing, and cost. Patients should work with their healthcare provider to determine which medication is the best choice for their individual needs and circumstances.