Eltrombopag is a medication designed to help individuals with abnormally low platelet counts. Platelets are tiny blood cells that play a fundamental role in stopping bleeding by forming clots. When platelet levels are low, a condition known as thrombocytopenia, the body’s ability to prevent bruising and bleeding is impaired. Eltrombopag works to address this by stimulating the production of new platelets within the body.
How Eltrombopag Works
The body’s natural production of platelets is regulated by a hormone called thrombopoietin (TPO). TPO is primarily produced in the liver and kidneys, traveling through the bloodstream to the bone marrow. There, it binds to specific receptors on the surface of cells called megakaryocytes, which are large cells responsible for producing platelets. This binding stimulates megakaryocytes to mature and proliferate, ultimately leading to the release of more platelets into the circulation.
Eltrombopag functions as a thrombopoietin receptor agonist. It is a non-peptide, small molecule, meaning it is not a protein like natural TPO and can be taken orally. Eltrombopag works by binding to a specific site on the TPO receptor located on megakaryocytes in the bone marrow. While its binding site is distinct from that of natural TPO, it effectively activates the receptor.
This activation triggers intracellular signaling pathways, including the Janus kinase (JAK) and signal transducer and activator of transcription (STAT) pathways. The activation of these pathways promotes the proliferation and differentiation of megakaryocytes, leading to an increased production of mature platelets.
Medical Uses
Eltrombopag is approved for treating several medical conditions characterized by low platelet counts. One such condition is chronic immune thrombocytopenia (ITP), an autoimmune disorder where the immune system mistakenly attacks and destroys the body’s own platelets. In individuals with chronic ITP who have not responded adequately to other treatments, eltrombopag helps increase platelet counts and reduce bleeding episodes.
The medication is also used in the treatment of severe aplastic anemia (SAA). SAA is a rare and serious blood disorder in which the bone marrow fails to produce enough new blood cells, including red blood cells, white blood cells, and platelets. Eltrombopag can stimulate the remaining bone marrow cells to produce more blood cells, including platelets, in patients who have had an insufficient response to immunosuppressive therapy.
Eltrombopag also addresses thrombocytopenia in patients with chronic hepatitis C (HCV) infection. Low platelet counts are common in HCV patients, which can complicate or prevent the initiation and maintenance of antiviral therapy. By increasing platelet counts, eltrombopag allows these patients to safely undergo antiviral treatment for their hepatitis C.
Important Considerations
Eltrombopag is an oral medication, typically taken once daily. It is usually advised to take it on an empty stomach, either at least one hour before or two hours after a meal, to enhance absorption and effectiveness. It is also recommended to avoid consuming dairy products or mineral supplements containing polyvalent cations, such as iron, calcium, magnesium, aluminum, selenium, and zinc, around the time of dosing, as these can interfere with the medication’s absorption.
Common side effects associated with eltrombopag can include headache, nausea, diarrhea, fatigue, and muscle aches. Some individuals may also experience elevated liver enzyme levels. These side effects are generally mild, but patients with pre-existing liver conditions, particularly those with advanced chronic hepatitis C, require close monitoring due to a potentially increased risk of serious liver problems.
Regular blood tests are important while taking eltrombopag. This includes monitoring platelet counts to ensure the medication is working effectively and adjusting the dose as needed. Liver function tests are also performed regularly to check for any signs of liver enzyme elevation or other liver-related issues. Healthcare providers also monitor for potential risks such as blood clots, as increasing platelet counts can, in some cases, increase this risk.