Platelets are tiny, colorless cell fragments in the blood that play a fundamental role in stopping bleeding. When a blood vessel is damaged, platelets rush to the site and clump together, forming a plug to seal the injury. This crucial process, known as hemostasis, prevents excessive blood loss. A low platelet count, medically termed thrombocytopenia, means there are fewer of these clotting cells than normal. This reduction can lead to an increased risk of bruising, spontaneous bleeding, and prolonged bleeding from injuries.
Medications That Stimulate Platelet Production
One approach to increasing platelet count involves stimulating the bone marrow to produce more of these cells. This is primarily achieved through a class of medications called thrombopoietin receptor agonists (TPO-RAs). These medications work by mimicking the natural hormone thrombopoietin (TPO), which is produced in the liver and regulates platelet production. TPO-RAs bind to receptors on bone marrow cells, activating pathways that promote megakaryocyte maturation and increase platelet release.
Several TPO-RAs are available, each with unique characteristics. Romiplostim, for instance, is a “peptibody” administered as a subcutaneous injection, typically once a week. Eltrombopag is an oral, non-peptide molecule that binds to a different site on the TPO receptor’s transmembrane domain but still achieves the same stimulatory effect. This oral medication’s absorption can be affected by certain foods, particularly those high in calcium.
Other oral TPO-RAs include avatrombopag and lusutrombopag. Avatrombopag is notable for not having the same dietary restrictions as eltrombopag, making it a flexible option for some individuals. Lusutrombopag is specifically approved for increasing platelet counts in patients with chronic liver disease undergoing certain procedures.
Medications That Reduce Platelet Destruction
Another strategy to increase platelet count focuses on reducing the premature destruction of platelets, particularly when the immune system is involved. Corticosteroids, such as prednisone and dexamethasone, are commonly used for this purpose. These medications suppress the overall immune system, which can reduce the production of antibodies that mistakenly target and destroy platelets. They can also decrease the activity of cells in the spleen that are responsible for clearing platelets from circulation.
Intravenous Immunoglobulin (IVIG) is another treatment that modulates the immune response to preserve platelets. IVIG is a blood product that modulates the immune response. It works by saturating receptors on immune cells that destroy antibody-coated platelets, preventing their destruction. IVIG can also neutralize harmful anti-platelet antibodies.
Anti-D immunoglobulin, also known as Rh immune globulin, is used in specific cases for individuals who are Rh-positive. This treatment works by binding to Rh-positive red blood cells, leading to their removal by the spleen. This process “distracts” the spleen, effectively sparing the antibody-coated platelets from destruction and allowing the platelet count to rise.
Important Considerations For Treatment
Medications to increase platelet count are typically prescribed for conditions where low platelet levels pose a bleeding risk. These include immune thrombocytopenia (ITP), an autoimmune disorder where the immune system attacks platelets. They are also used for chemotherapy-induced thrombocytopenia, a common side effect of cancer treatment that damages bone marrow cells. Additionally, certain liver diseases, like cirrhosis, can cause low platelet counts, making these medications relevant for managing bleeding risks during procedures.
Patients receiving TPO-RAs may experience side effects, including an increased risk of blood clots. Other reported side effects can include headache, fatigue, or joint pain. Eltrombopag has been associated with elevated liver enzymes and, in some instances, cataract formation. For medications that suppress the immune system, such as corticosteroids and IVIG, an increased susceptibility to infections is a consideration. Corticosteroids, if used long-term, can also lead to weakened bones, elevated blood sugar levels, and mood changes.
Given the potential for side effects and the varied responses to treatment, medical supervision is essential. Regular monitoring of platelet counts, along with other blood parameters through a complete blood count, is necessary to assess treatment effectiveness and adjust dosages. Treatment plans are personalized, taking into account the specific cause of thrombocytopenia, the patient’s overall health, and their response to therapy.