Romiplostim

also known as: Nplate, AMG 531, TPO mimetic peptibody

A peptibody that boosts platelet production — an Fc-fused peptide mimicking thrombopoietin, FDA-approved for immune thrombocytopenia.

A recombinant peptide-Fc fusion protein containing four copies of a 14-amino-acid TPO-mimetic peptide fused to an IgG1 Fc domain, FDA-approved for immune thrombocytopenia (ITP).

Mechanism of action

Four TPO-mimetic peptides bind c-Mpl (TPO receptor) on megakaryocyte progenitors, triggering JAK2/STAT5 and MAPK signaling to promote platelet production. Fc domain provides extended half-life via FcRn recycling. No homology with endogenous TPO.

Primary uses

Chronic immune thrombocytopenia (FDA-approved)
ITP refractory to corticosteroids, IVIG, or splenectomy

Typical dosing

1-10 mcg/kg once weekly (subcutaneous)

Start 1 mcg/kg SC weekly. Titrate to platelet count >=50,000/mcL. Max 10 mcg/kg.

Regulatory status

FDA-approved August 2008 as Nplate for chronic ITP in adults. Expanded to pediatric ITP in 2018. Developed by Amgen. First 'peptibody' approved by the FDA.

References

[pubmed] Kuter DJ, et al. "Efficacy of romiplostim in patients with chronic immune thrombocytopenic purpura." Lancet. 2008;371(9610):395-403.

Related peptides

Thymosin α1

The most clinically studied thymic peptide — approved in 35+ countries as Zadaxin for hepatitis B and C, with 30+ RCTs across more than 11,000 subjects. Not FDA-approved despite extensive global use.

Thymopentin

A synthetic pentapeptide fragment of thymopoietin — historically marketed as Timunox for immunodeficiency, now primarily used in research and limited European clinical practice.

Erythropoietin (EPO)

A glycoprotein hormone that drives red blood cell production; recombinant forms are FDA-approved standards of care for anemia of chronic kidney disease and chemotherapy-induced anemia, and have a notorious history of misuse in endurance sport.

Disclaimer

This entry is for educational purposes only and does not constitute medical advice. Dosing information reflects published regulatory or research data and is not a recommendation. Many compounds described here are not approved for human use in the United States. Consult a licensed medical professional before considering any peptide therapy.