Steroids

Corticosteriods are given as a brief, initial treatment. These prevent bleeding by decreasing platelet destruction and can increase platelet count in 2-3 weeks. An infusion of high-dose dexamethasone or methylprednisone is given in urgent situations; oral forms (e.g. prednisone, prednisolone) are given in less severe cases. As the platelet count improves, the dose is gradually reduced; 60–90% will experience a relapse during dose reduction or cessation. Long-term steroids are avoided due to potential side effects such as osteoporosis, diabetes, and cataracts (Bussel, 2019).

Rho (D) immune globulin (Anti-D or Rh immune globulin)

This is given to Rh-positive patients with functional spleens. It is administered intravenously and temporarily stops the spleen from destroying platelets. However, it is used with caution because it may cause the destruction of red blood cells. The mechanism of action of anti-D is not fully understood. After administration, anti-D-coated red blood cell complexes saturate Fcy receptor sites on macrophages, and this results in preferential destruction of red blood cells (RBCs) and spares antibody-coated platelets. Products indicated for use are WinRho® SDF and rhophylac. The most common adverse reactions are as follows (Heitink-Pollé et al., 2018):

• Headache (15%)
• Nausea or vomiting (12%)
• Chills (<2%)
• Fever (1%)

Steroid-sparing agents

There is an increasing use of immunosuppressants as second-line agents (e.g., mycophenolate mofetil and azathioprine). For chronic refractory cases, where immune pathogenesis has been confirmed, vinca alkaloid (off-label use) and vincristine (chemotherapy agent) may be used. However, vincristine has significant side effects, so it is used with caution in children (Bussel, 2019).

Intravenous immunoglobulin (IVIg)

This may be infused in some cases to decrease the rate at which macrophages consume antibody-tagged platelets. It is sometimes effective. Although costly, IVIg produces improvement that generally lasts less than a month. For dangerously low platelet counts and poor response to other treatments, IVIg can rapidly increase platelet counts, reducing the risk of major bleeding. A single dose of IVIg is administered to slow the destruction of platelets. It works more quickly than steroids (within 24–48 hours). (Heitink-Pollé et al., 2018)

Thrombopoietin receptor agonists

These are used stimulate platelet production in the bone marrow in an attempt to curtail platelet destruction. Romiplostim (Nplate), a thrombopoiesis-stimulating Fc-peptide fusion protein (peptibody), is administered by subcutaneous injection. Eltrombopag (Promacta in the United States, Revolade in the EU), an orally-administered agent with an effect similar to that of romiplostim, increases platelet counts and decreases bleeding in a dose-dependent manner. Side effects of thrombopoietin receptor agonists include the following (Bussel, 2019):

• Headache
• Joint or muscle pain
• Dizziness
• Nausea or vomiting
• Increased risk of blood clots

Surgery

Splenectomy is considered in patients who are unresponsive to steroid treatment, have frequent relapses, and cannot be tapered off steroids after a few months. Splenectomy reduces platelet destruction (platelet macrophages have Fc receptors that do this), but it is risky due to the increased possibility of significant bleeding during surgery. Durable remission following splenectomy is achieved in 75% of ITP cases. This method to treat ITP has diminished since the development of steroid therapy and other pharmaceutical remedies. (Bussel, 2019)

Platelet transfusion

This is normally not recommended except in an emergency. This is usually unsuccessful in producing a long-term platelet count increase. An underlying autoimmune mechanism that is destroying the patient's platelets will also destroy donor platelets. Hence, platelet transfusions are not considered a long-term treatment option (Bussel, 2019).

Other agents

Dapsone (idiphenylsulfone, DDS, avlosulfon) is an anti-infective sulfone medication that may be helpful in treating lupus and rheumatoid arthritis and is used as a second-line treatment for ITP [mechanism is unclear] (Grace et al., 2018). Off-label use of Rituximab may help increase platelets and may sometimes be an effective alternative to splenectomy. However, it has significant side effects (Bussel, 2019).