Romiplostim, sold under the brand name Nplate among others, is a fusion protein analog of thrombopoietin, a hormone that regulates platelet production.

The most common side effects in adults include headache, infections of the nose and throat, and allergic (hypersensitivity) reactions such as rash, itching and rapid swelling under the skin.

[1] Romiplostim is indicated as a potential treatment for chronic idiopathic (immune) thrombocytopenic purpura (ITP).

[2] In well designed, 24-week, Phase III trials, romiplostim was significantly more effective than placebo in achieving the primary endpoint of a protocol-defined durable platelet response in nonsplenectomized or splenectomized adults with chronic immune thrombocytopenic purpura.

[5] Romiplostim was designated an orphan drug by the US Food and Drug Administration (FDA) in 2003[6] In August 2008, the FDA approved romiplostim as a long-term treatment for chronic immune thrombocytopenia in adults who have not responded to other treatments, such as corticosteroids, intravenous immunoglobulin, Rho(D) immune globulin or splenectomy.