Approved August 22, 2008

ROMIPLOSTIM
(FDA Category 1S)

NPLATE (TM) (Amgen, Inc) an Fc-peptide fusion protein (peptibody), increases platelet production through binding and activation of the thrombopoietin (TPO) receptor, a mechanism similar to endogenous TPO.

DOSING INFORMATION: The recommended initial dose is 1 mcg/kg subcutaneously based on actual body weight once a week, adjusted weekly in increments of 1 mcg/kg to achieve a platelet count greater than or equal to 50 x 10(9)/liter. The maximum weekly dose is 10 mcg/kg. Use the lowest dose possible to achieve and maintain a platelet count greater than or equal to 50 x 10(9)/liter. In clinical studies, a median dose of 2 mcg/kg was effective in most patients. A stable platelet count is achieved if the count is 50 x 10(9)/liter or greater for at least 4 weeks without any romiplostim dose adjustments required. If after 4 weeks of romiplostim therapy at the maximum weekly dose of 10 mcg/kg subcutaneously, the platelet count response is not adequate to control bleeding, discontinue therapy and continue monitoring platelets for 2 weeks following discontinuation of romiplostim.

PHARMACOKINETICS: In patients with chronic ITP, after a single subcutaneous dose of 1 to 10 mcg/kg of romiplostim, the peak platelet count was 1.3 to 14.9 times greater than the baseline count over a 2 to 3 week period. Dose-dependent increases in platelet counts were observed. Peak serum concentrations of romiplostim were observed 7 to 50 hours post dose (median: 14 hours) at a dose range of 3 to 15 mcg/kg. The elimination of serum romiplostim is partially dependent on the thrombopoietin receptor on platelets. Half-life is 1 to 34 days (median: 3.5 days).

CAUTIONS: The risk of reticulin deposition within the bone and hematological malignancies are increased. Thrombocytopenia may worsen after discontinuation of romiplostim. Thrombotic/thromboembolic complications may occur. Romiplostim is only available through a restricted distribution program (Nplate NEXUS, 1-877-675-2831). The most common adverse effects are headache, arthralgia, dizziness, insomnia, myalgia, pain in extremity, abdominal pain, shoulder pain, dyspepsia, and paresthesia.

FDA APPROVED INDICATIONS: Romiplostim is indicated for the treatment of thrombocytopenia to reduce the risk of bleeding in patients with chronic immune idiopathic thrombocytopenic purpura when there has been inadequate response to corticosteroids, immunoglobulins, or splenectomy.