Romiplostim — Drug Monograph

Brand names: Nplate

Drug class: Supportive Care Agent

Mechanism of Action

Recombinant fusion protein ("peptibody") — an Fc-domain carrier fused to peptide sequences that bind and activate the thrombopoietin receptor (TPO-R / c-Mpl). It has no sequence homology to endogenous thrombopoietin (reducing the risk of neutralizing cross-reactive antibodies) but reproduces TPO's effect: activation of JAK2/STAT5 signaling to stimulate megakaryocyte proliferation, differentiation, and platelet production. Administered subcutaneously once weekly.

FDA Indications

• Chronic immune thrombocytopenia (ITP) in adults with insufficient response to corticosteroids, immunoglobulins, or splenectomy
• Immune thrombocytopenia (ITP) in pediatric patients ≥1 year with ITP for ≥6 months and insufficient response to prior therapy
• Hematopoietic subsyndrome of acute radiation syndrome (H-ARS) in adults and pediatric patients (including term neonates) to increase survival after acute myelosuppressive radiation exposure

Common Side Effects

• Headache
• Arthralgia
• Fatigue
• Insomnia
• Injection site reactions
• Myalgia
• Dizziness

Clinical Pearl

Romiplostim is the only weekly subcutaneous TPO-RA, making it useful when oral adherence or absorption (food/cation restrictions with eltrombopag) is a concern. Its "peptibody" design deliberately shares no sequence with native thrombopoietin, avoiding the cross-reactive neutralizing antibodies that doomed earlier recombinant TPO molecules. Because small dosing volumes invite measurement errors, always use the dedicated reconstitution and low-volume administration steps.

Related Therapies & Mechanisms

• Avatrombopag (Doptelet) — Supportive Care Agent · Supportive Care
• Defibrotide (Defitelio) — Supportive Care Agent · Supportive Care
• Dexrazoxane (Zinecard) — Supportive Care Agent · Supportive Care
• Eltrombopag (Promacta) — Supportive Care Agent · Supportive Care