PHILADELPHIA, Nov. 21 -- The FDA has approved oral eltrombopag (Promacta) for adult patients with refractory chronic immune thrombocytopenic purpura, the drug's maker announced.
Eltrombopag's label will carry a boxed warning about hepatotoxicity risks.
The approval marked the second platelet stimulator for refractory ITP. Last August, the FDA has approved romiplostim (Nplate), which is delivered by subcutaneous injection. (See: FDA Approves Platelet Stimulator as Second Line Therapy for Chronic ITP)
The eltrombopag warning advises clinicians to perform regular serum liver tests and to discontinue treatment if alanine aminotransferase levels increase to three times the upper limit of normal and are progressive or persistent for four weeks, accompanied by increased direct bilirubin, or accompanied by symptoms of liver injury or evidence for hepatic decompensation.
Restarting treatment after discontinuation was discouraged.
Because of the risks, eltrombopag will only be available through a restricted distribution program called Promacta Cares, which is being launched by GlaxoSmithKline, the drug's manufacturer. Physicians, pharmacies, and patients are required to enroll in the program before prescribing, distributing, or receiving the drug.
Additional precautions warned of the possible development or progression of reticulin fibers within the bone marrow, worsened thrombocytopenia following discontinuation of the drug, thromboembolic complications, and cataract.
The drug is indicated for patients who have not responded to corticosteroids, immunoglobulins, or splenectomy.
The approval was made on the basis of results from two randomized, placebo-controlled trials in patients given eltrombopag for up to six weeks, and a longer-term open-label extension study.
Adverse events that were more common with eltrombopag than with placebo included nausea, vomiting, menorrhagia, myalgia, paresthesia, cataract, dyspepsia, ecchymosis, thrombocytopenia, increased liver enzymes, and conjunctival hemorrhage.
Eltrombopag is a thrombopoietin receptor agonist that stimulates the proliferation and differentiation of megakaryocytes, which give rise to platelets.
The initial dosage will be 50 mg once daily for most patients. A 25-mg dose will be used for patients of East Asian ancestry and for those with moderate to severe hepatic insufficiency.
According to the label, eltrombopag should be discontinued if platelet counts have not increased to a level sufficient to prevent clinically significant bleeding after four weeks.