Phosphorus is a mineral found in many different types of foods which is necessary for keeping our bones healthy. However, if our bodies have too much phosphorus (hyperphosphatemia), it can cause chemical changes which pull calcium out of our bones and cause hypocalcemia (low calcium levels). Calcium is essential for strong, healthy bones, which is why it can be dangerous for phosphorus levels to get too high. Excess phosphorus can also cause other serious health complications throughout the body. The kidneys are responsible for removing excess phosphorus from the body, but in people with CKD, this process is far less effective.
Kidney dialysis can help to remove some excess phosphorus from the body in people with CKD, but in some cases, it may not be enough to prevent hyperphosphatemia and hypocalcemia. This is why phosphate binders like sevelamer are used. The drug is taken at the same time as meals in order to bind to the phosphorus in the food so that it doesn’t remain in the body. Often, patients will also be advised to control their diet to minimize their intake of foods which contain high amounts of phosphorus.
In the US, sevelamer is administered orally and is available in tablet, powder and capsule forms. It is sold under the brand names Renagel and Renvela.
As well as having its intended effect of managing phosphorus levels, sevelamer can also cause unwanted effects. Some of these unwanted effects are serious and should be immediately reported to a doctor. If you notice any of the following symptoms when you start taking sevelamer, contact your doctor urgently or visit the emergency room:
Some side effects associated with sevelamer are relatively minor and do not require medical attention unless they become very severe or bothersome. In some instances, they may go away as your body adjusts to the medicine. If in doubt whether a side effect needs medical treatment, contact your doctor for advice. Some of the more common minor side effects associated with sevelamer include:
In very rare instances, sevelamer can cause a rash and itchy skin. Usually, this isn’t something to worry about unless it becomes severe and widespread very quickly.
If you notice any other side effects not listed here, consult your doctor. You could also report side effects to the FDA.
The amount of sevelamer you take will depend on your blood phosphorus levels. Always follow your doctor’s instructions. Your dose may be adjusted depending on your progress; you will probably be required to have frequent blood tests to check your phosphorus levels.
Renvela (powder for suspension)
For patients switching from Renegal tablets to Renvela (which should only be done under your doctor’s instruction), you should take the equivalent dose in milligrams. Your doctor may then adjust the dose as necessary.
Sevelamer tablets should be consumed with meals. Simply swallow each tablet whole, without breaking, crushing or chewing it, at the same time as your meal. If you have trouble swallowing sevelamer tablets or feel as though the tablet gets stuck in the esophagus after taking it, consult your doctor immediately.
If you have been prescribed sevelamer powder, thoroughly read the information leaflet provided with the medicine as this will instruct you how to take it correctly.
The powder can be mixed with water and drunk as a solution. The instruction leaflet will tell you how much water to use, but usually it is:
Stir the mixture thoroughly and drink it within 30 minutes of preparation. Bear in mind that the mixture will be cloudy since the powder does not dissolve. The mixture may begin to separate within the 30-minute period, so you may need to stir it again before drinking.
You may also be able to mix sevelamer powder with other beverages or food, but you should not add it to hot food or drinks and you should not heat or microwave foods or drinks which contain the powder. As when mixing it with water, you must consume the powder within 30 minutes of preparing it.
If you forget a dose of sevelamer, simply skip it and continue with your normal dosing schedule. The drug is designed to be taken with meals, so if you forget to take it at the time that you are eating, do not take it afterwards.
Sevelamer may make it difficult for other medicines to be absorbed by the body. For this reason, your doctor may give you new instructions as to the time at which you should take your existing medicines and sevelamer. For example:
Sevelamer should not be taken by patients with bowel blockage conditions, as it could make the bowel blockage worse or the absorption of the drug may be inhibited.
Some other stomach or bowel problems, such as constipation, and past major surgery on the gastrointestinal tract, could also affect the way that the drug is absorbed by the body. Depending on the nature of these problems, your doctor may choose not to prescribe sevelamer to you.
If you have had problems with swallowing in the past, your doctor may not prescribe sevelamer as it could cause serious side effects if it becomes lodged in the esophagus. If they do prescribe the drug, they may be more likely to prescribe it in powder form since this is usually easier to swallow than the tablet form.
Only use the brand of sevelamer prescribed to you
Sevelamer is available under two brand names in the US, Renagel and Renvela. There may be differences in the ways the two brands are designed to be used, so only use the brand that your doctor has prescribed. Do not switch to the other brand unless directed by your doctor.
There have not been enough studies performed to assess the safety and efficacy of sevelamer in children. For this reason, sevelamer may not be prescribed to children unless a doctor has deemed it appropriate. In these instances, dosages will be decided by the doctor.
Sevelamer appears to be just as effective and safe in elderly patients as it is in younger adults. However, elderly patients will typically start sevelamer at a lower dose than younger adults.
Sevelamer is a pregnancy category C drug, which means it should only be used if the benefits of the drug far outweigh potential risks to the fetus. There is limited data on the safety of sevelamer when taken by pregnant women, but animal studies have demonstrated an increased risk of fetal damage.
It isn’t known whether sevelamer is excreted in human breast milk, but the nonabsorbent nature of the drug makes it unlikely. Despite this, since no studies have been performed to check if the drug is excreted and, if so, what effects it could have on a nursing infant, the drug should only be used by breastfeeding women if the benefits far outweigh potential risks.
Phosphorus enters our bodies via the foods we eat. Some foods contain more phosphorus than others or allow phosphorus to be more easily and readily absorbed than others. For this reason, your doctor may instruct you to adopt a low-phosphorus diet while taking sevelamer. It is very important that you follow this diet as closely as possible. Your doctor may be able to refer you to a nutritionist who will help you to adjust to a new, balanced diet which contains minimal phosphorus.
Your doctor will want to closely monitor your progress when you take sevelamer, particularly when you first start taking the medicine. You can expect to have regular blood tests, with your dose being adjusted perhaps once every two weeks if necessary.
Sometimes sevelamer can reduce levels of folic acid and some vitamins in the body. Your doctor may test vitamin and mineral levels regularly throughout your sevelamer therapy and they may prescribe supplements where necessary. Only take additional supplements and multivitamins with your doctor’s approval.
You should store sevelamer in the container it came in at room temperature and away from direct light, heat and moisture. Do not keep it in the bathroom where it could be exposed to humid conditions.
Make sure the sevelamer container is tightly closed at all times and stored up and away from the ground so that it is not within easy reach of children or pets. Avoid keeping the medicine in pill boxes that do not have child-resistant safety caps.
Do not store unused medicine. Instead, ask your healthcare provider for advice on how to correctly dispose of it. Do not flush it down the toilet. Your healthcare provider may have a medicine take-back program available which ensures safe disposal of unused drugs.
Sevelamer is a phosphate binder which helps to prevent high phosphate levels in patients with chronic kidney disease (CKD) who are undergoing dialysis.
CKD makes it difficult for the body to remove excess phosphorus, and high levels of the mineral can cause calcium to be pushed out of the bones, leading to bone weakness and other serious complications. Sevelamer is taken with food and binds with the phosphorus in food so that it is not absorbed by the body.
Available in powder and tablet forms, sevelamer is known in the US under brands names Renegal and Renvela. It is suitable for adult and elderly patients, but is not recommended for children or pregnant women. It is also not suitable for patients with stomach or intestinal blockages.
More common side effects, which don’t require medical attention, include sour stomach, bloating, mild stomach upset and constipation. If patients experience black or bloody stools, vomiting, prolonged constipation, severe pain or cramping in the stomach or abdomen, or difficulty swallowing, they should consult a doctor urgently.