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ITP–General Information

Incidence and prevalence of ITP

Idiopathic thrombocytopenic purpura (ITP), also known as primary immune thrombocytopenic purpura and autoimmune thrombocytopenic purpura, is a clinical syndrome in which a decreased number of circulating platelets manifests as a bleeding tendency, easy bruising, or extravasation of blood from capillaries into skin and mucous membranes.1

ITP is primarily a disease of increased peripheral platelet destruction, with most patients having antibodies to specific platelet membrane glycoproteins.1

Acute ITP typically follows an acute infection and resolves within 2 months. Chronic ITP persists for more than 6 months with no specific cause.1

In the United States, the incidence of ITP in adults is approximately 66 cases per 1,000,000 per year. An average estimate of the incidence in children is 50 cases per 1,000,000 per year. New cases of chronic refractory ITP comprise approximately 10 cases per 1,000,000 per year.

ITP has also been studied internationally, and according to studies in Denmark and England, childhood ITP occurs in approximately 10 to 40 cases per 1,000,000 per year. A study in Kuwait reported a higher incidence of 125 cases per 1,000,000 per year.1

Signs and symptoms of ITP

Common signs and symptoms include1

  • nonpalpable petechiae, which mostly occur in dependent regions
  • purpura
  • gingival bleeding/epistaxis
  • menorrhagia
  • bruising tendency
  • signs of GI bleeding
  • nonpalpable spleen
  • retinal hemorrhages
  • hemorrhagic bullae on mucous membranes
  • spontaneous bleeding when platelet count is less than 20,000/mm3
  • intracranial hemorrhage, with possible neurologic symptoms

Precipitating factors include

  • recent live virus immunization (childhood ITP)
  • recent viral illness (childhood ITP)

Diagnosing ITP

There is no single laboratory result or clinical finding that can establish a diagnosis of ITP; the type and severity of bleeding must be evaluated and other causes of bleeding excluded.

Alternative diagnoses that should be eliminated include1

  • liver disease
  • myelodysplasia
  • lymphoproliferative, autoimmune, or infectious diseases
  • pregnancy-associated thrombocytopenia
  • drug-induced immune thrombocytopenia (alcohol, heparin, quinine/quinidine, sulfonamides)
  • infection/sepsis
  • acute leukemia
  • myelodysplastic syndrome
  • malignancy
  • megaloblastic anemia
  • isoimmune neonatal purpura
  • transfusion

Treatment of ITP

In children, ITP often runs its course without the need for treatment. About 80% of children recover completely within 6 months.1 Adults with platelet counts <50,000/mm3 require treatment.2

Treatment of ITP may be coordinated with a hematologist. Glucocorticoids and IGIV are the current standards of treatment. IGIV is used when a rapid elevation in platelet count is needed, such as in the case of critical bleeding or in preparation for surgery.1

Important Safety Information for GAMUNEX

Gamunex, Immune Globulin Intravenous (Human), 10% Caprylate/Chromatography Purified, is indicated for the treatment of primary humoral immunodeficiency disease (PI), idiopathic thrombocytopenic purpura (ITP), and chronic inflammatory demyelinating polyneuropathy (CIDP).

Immune Globulin Intravenous (Human) products have been reported to be associated with renal dysfunction, acute renal failure, osmotic nephrosis and death. Patients predisposed to acute renal failure include patients with any degree of pre-existing renal insufficiency, diabetes mellitus, age greater than 65, volume depletion, sepsis, paraproteinemia, or patients receiving known nephrotoxic drugs. Especially in such patients, IGIV products should be administered at the minimum concentration available and the minimum rate of infusion practicable. While these reports of renal dysfunction and acute renal failure have been associated with the use of many of the licensed IGIV products, those containing sucrose as a stabilizer accounted for a disproportionate share of the total number. Gamunex does not contain sucrose. Glycine, a natural amino acid, is used as a stabilizer.

Gamunex is contraindicated in individuals with acute severe hypersensitivity reactions to Immune Globulin (Human). It is contraindicated in IgA deficient patients with antibodies against IgA and history of hypersensitivity.

There have been reports of noncardiogenic pulmonary edema [Transfusion-Related Lung Injury (TRALI)], hemolytic anemia, and aseptic meningitis in patients administered with IGIV.

Thrombotic events have been reported in association with IGIV. Patients at risk for thrombotic events may include those with a history of atherosclerosis, multiple cardiovascular risk factors, advanced age, impaired cardiac output, and/or known or suspected hyperviscosity. Hyperproteinemia, increased serum viscosity, and hyponatremia may occur in patients receiving IGIV therapy.

Gamunex is made from human plasma. Because this product is made from human plasma, it may carry a risk of transmitting infectious agents, e.g., viruses, and, theoretically, the Creutzfeldt-Jakob disease (CJD) agent.

In clinical studies, the most common adverse reactions with Gamunex were headache, fever, chills, hypertension, rash, nausea, and asthenia (in CIDP); headache, cough, injection site reaction, nausea, pharyngitis, and urticaria (in PI); and headache, vomiting, fever, nausea, back pain, and rash (in ITP). The most serious adverse reactions were pulmonary embolism (PE) in one subject with a history of PE (in CIDP), an exacerbation of autoimmune pure red cell aplasia in one subject (in PI), and myocarditis in one subject that occurred 50 days post-study drug infusion and was not considered drug related (in ITP).

Please see accompanying GAMUNEX full Prescribing Information for complete prescribing details.

You are encouraged to report negative side effects of prescription drugs to the FDA.
Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.

References:

  1. Silverman MA. Idiopathic thrombocytopenic purpura. January 2007. eMedicine article. http://www.emedicine.com/emerg/topic282.htm.
    Accessed May 20, 2009.

  2. Sandler SG, Bhanji R. Immune thrombocytopenic purpura. May 2006. eMedicine article. http://www.emedicine.com/med/topic1151.htm.
    Accessed May 20, 2009.