Erythropoietin Stimulating Agents
What is erythropoietin?
Red blood cells are produced in the bone marrow (the spongy tissue inside the bone). In order to make red blood cells, the body maintains an adequate supply of erythropoietin (EPO), a hormone that is produced by the kidney.
EPO helps make red blood cells. Having more red blood cells raises your hemoglobin levels. Hemoglobin is the protein in red blood cells that helps blood carry oxygen throughout the body.
Anemia is a disorder that occurs when there is not enough hemoglobin in a person's blood. There are several different causes of anemia. For instance, anemia can be caused by the body's inability to produce enough EPO to make red blood cells. If this is the case, the person may have to have a blood transfusion to treat this type of anemia. If you have anemia, your physician can determine the cause.
What is recombinant erythropoietin?
In cases where transfusions are not an option—for example, when the patient cannot have, or refuses, a transfusion—it may be necessary to give the patient recombinant erythropoietin. Recombinant erythropoietin is a man-made version of natural erythropoietin. It is produced by cloning the gene for erythropoietin.
Recombinant erythropoietin drugs are known as erythropoietin-stimulating agents (ESAs). These drugs are given by injection (shot) and work by stimulating the production of more red blood cells. These cells are then released from the bone marrow into the bloodstream.
There are two ESAs on the U.S. market: epoetin alfa (Procrit,® Epogen®), and darbepoietin alfa (Aranesp®).
Who receives ESAs?
ESAs are usually given to patients who have chronic (long-lasting) kidney disease or end-stage renal (kidney) disease. These patients usually have lower hemoglobin levels because they can't produce enough erythropoietin.
ESAs are also prescribed for patients who have cancer. These patients often have anemia, which can be caused by chemotherapy.
What are the side effects of ESAs?
The side effects that occur most often with ESA use include:
What should the patient consider before using ESAs?
There are several safety issues with ESAs:
- ESAs increase the risk of venous thromboembolism (blood clots in the veins). A blood clot can break away from one location and travel to the lung (pulmonary embolism), where it can block circulation. Symptoms of blood clots include chest pain, shortness of breath, pain in the legs, and sudden numbness or weakness in the face, arm, or leg.
- ESAs can cause hemoglobin to rise too high, which puts the patient at higher risk for heart attack, stroke, heart failure, and death.
- In patients who have cancer, ESAs may cause the tumor to grow. If ESAs are used for these patients, they are usually stopped after the patient's chemotherapy is finished.
- The health care provider will keep an eye on the patient's blood cell counts to make sure they do not put him or her at a higher risk. The dosing may change, depending on the patient's needs.
Patients who have the following conditions need to consult with their health care provider if an ESA is being considered as part of the treatment plan:
- Heart disease
- High blood pressure
- Porphyria (a group of diseases that are caused by enzyme deficiencies)
- An allergy to epoetin alfa or any other part of this medicine
- Uncontrolled high blood pressure
In addition, women who are pregnant, planning to become pregnant, or breastfeeding should consult with their health care provider before taking an ESA.
Other issues to consider:
- Transfusions may improve symptoms of anemia right away. ESAs may take from weeks to months to provide noticeable relief of the symptoms of anemia.
- If a patient has several transfusions, he or she can develop an "iron overload," or high iron levels. This is a serious medical problem.
- Iron supplements are often needed for patients who are on ESAs.
- Keep your health care provider informed about any change in your condition.
- Check your blood pressure and heart rate as recommended by your health care provider.
- Remain informed about the results from any blood work that is done.
- The body may develop antibodies to an ESA. If this happens, the antibodies will block or lessen the body's ability to make red blood cells. This could result in an anemia. It is important that the patient keep the health care provider informed of any unusual tiredness, lack of energy, dizziness, or fainting.
- If you have a life-threatening allergy, wear allergy identification at all times.
- Do not share your medicine with others and do not take anyone else's medicine.
- Keep all medicine out of the reach of children and pets.
- Keep a list of all your medicines (prescription, natural products, supplements, vitamins, over-the counter) with you.
- Call your physician for medical advice about any side effects.
- Talk with your health care provider before starting any other new medicine, including over-the counter products, natural products, or vitamins.
- You may report side effects to the FDA at 1.800.FDA.1088.