Chemotherapy and Drug Therapy
Drug therapy is used for polycythemia vera (PV) to lower platelet count. Your doctor may use one or more of the following drugs:
Aspirin therapy. Low-dose aspirin may lessen your risk of developing a blood clot in an artery (thrombosis). It acts by making platelets less likely to clump to an artery wall. Aspirin is given by mouth.
Anagrelide (Agrylin®). Anagrelide, given by mouth, can be used to reduce the rate that platelets form in the marrow without affecting the other blood cells. Anagrelide may cause side effects, including fluid retention, heart and blood pressure problems, headaches, dizziness, nausea and diarrhea. Older patients and patients with heart disease are generally not treated with anagrelide.
Antihistamines or related drugs. These drugs may be prescribed to relieve itching and are given by mouth. Side effects include dry mouth, drowsiness, dizziness and restlessness. Some antihistamines can impair a person?s ability to drive or operate heavy machinery.
Myelosuppressive drugs. Myelosuppressive drugs are agents that can reduce red cell or platelet concentrations. In some patients, phlebotomy alone can't control the overproduction of red cells and can contribute to the platelets' overproduction. Myelosuppressive agents may be used if you have an extremely high platelet count, complications from bleeding or blood clots or other serious complications that don't respond to low-dose aspirin or phlebotomy. Your doctor may either combine drug therapy with phlebotomy or use it to replace phlebotomy to suppress your marrow's red cell and platelet production.
Hydroxyurea (Hydrea®). The most commonly used myelosuppressive agent for PV is hydroxyurea, given in pill form. It has few side effects and helps to reduce the hematocrit or hemoglobin concentration and platelet count. There is some controversial evidence that, after long-term therapy, hydroxyurea is associated with an increased risk for patients to develop acute leukemia, so is frequently avoided as therapy for younger patients. However, it is thought to have much less potential for causing leukemia than other myelosuppressive agents, such as radiophosphorus and alkylating agents, which include melphalan (Alkeran®), busulfan (Myleran®), chlorambucil (Leukeran®) and others. Radiophosphorous and alkylating agents are reserved for patients with short life expectancy.
Interferon alfa (Intron® A, Roferan-A®). Interferon alfa and other chemotherapy agents are available but aren't used in most patients because they're inconvenient to administer (they are given by intramuscular or subcutaneous injection) and may have frequent side effects. Some patients develop moderately severe flu-like symptoms, confusion, depression or other complications. Development of sustained-release preparations provides a new option for patients; injections would be weekly, a regimen patients tend to tolerate better (particularly in the case of Pegasys).
If you would like to read about these drugs individually, including information about side effects, click here.