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#86

Romiplostim

HematologyNplateAMG 531Romiplostim Injection

A peptibody (peptide-Fc fusion protein) thrombopoietin receptor agonist that stimulates platelet production, FDA-approved for chronic immune thrombocytopenia in patients with insufficient response to other treatments.

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Overview

Romiplostim is a novel fusion protein termed a "peptibody," consisting of two identical peptide sequences that bind and activate the thrombopoietin (TPO) receptor (also known as c-Mpl), linked to a human IgG1 Fc domain. Developed by Amgen and approved by the FDA in 2008, romiplostim was one of the first thrombopoietin receptor agonists (TPO-RAs) approved for clinical use, representing a paradigm shift in the management of chronic immune thrombocytopenia (ITP).

ITP is an autoimmune condition in which antibodies target platelets for destruction and also suppress megakaryocyte platelet production in the bone marrow. Traditional treatments (corticosteroids, splenectomy, immunosuppressants) focused on reducing platelet destruction, but romiplostim addresses the disease from the production side by directly stimulating megakaryocyte proliferation and differentiation, resulting in increased platelet production.

The TPO-binding peptide sequences in romiplostim have no amino acid sequence homology to native TPO, which is important because it means romiplostim does not induce anti-TPO antibodies that could cross-react with endogenous thrombopoietin and cause severe thrombocytopenia. The Fc domain extends the half-life and allows for once-weekly dosing.

Pivotal clinical trials demonstrated that romiplostim significantly increased platelet counts to safe levels (≥50,000/μL) in approximately 80-90% of patients with chronic ITP, allowing reduction or discontinuation of concurrent ITP therapies in many cases. The drug requires individualized dose titration based on weekly platelet counts, starting at 1 mcg/kg and adjusting by 1 mcg/kg per week to maintain platelets in the target range. Long-term studies have shown sustained platelet responses over several years of treatment.

Research Uses & Applications

  • FDA-approved treatment of chronic ITP in adults with insufficient response to corticosteroids, immunoglobulins, or splenectomy
  • FDA-approved for pediatric ITP patients aged 1 year and older with insufficient response to prior therapy
  • Reduction of concurrent ITP medication doses (steroid-sparing effect)
  • Pre-procedural platelet count elevation in ITP patients requiring surgery
  • Investigated for other thrombocytopenic conditions (MDS, chemotherapy-induced, aplastic anemia)
  • Research into thrombopoietin receptor agonist biology

Key Research Findings

  • Pivotal trials showed romiplostim achieved durable platelet response (≥50,000/μL) in approximately 80-90% of chronic ITP patients.
  • Long-term extension studies demonstrated sustained efficacy over 5+ years with continued weekly dosing.
  • Studies showed romiplostim allows reduction or discontinuation of concurrent ITP therapies (corticosteroids, immunosuppressants) in approximately 70% of patients.
  • Research in pediatric ITP confirmed efficacy and safety similar to the adult population.
  • Bone marrow studies showed reticulin fibrosis in some long-term treated patients, though clinical significance remains debated.

Risks & Side Effects

  • Rebound thrombocytopenia after discontinuation, with platelet counts potentially dropping below baseline; gradual tapering recommended.
  • Bone marrow reticulin fibrosis observed in some patients; periodic monitoring with blood smears recommended.
  • Thrombotic/thromboembolic events (DVT, PE, stroke) reported, likely related to platelet count elevation; target platelet count should avoid excessive levels.
  • Headache, fatigue, arthralgia, and dizziness reported as common side effects.
  • Risk of progression to myelodysplastic syndrome or acute myeloid leukemia in patients with MDS treated with romiplostim (not approved for this indication).

Administration

Administered as weekly subcutaneous injection. Starting dose: 1 mcg/kg based on actual body weight. Dose adjusted by 1 mcg/kg per week to achieve platelet count ≥50,000/μL while avoiding excessive counts. Maximum dose: 10 mcg/kg/week. Platelet counts monitored weekly during dose adjustment and monthly once stable. Reconstituted from lyophilized powder before injection.

Legal Status

FDA-approved prescription medication marketed as Nplate. Approved for chronic ITP in adults and children ≥1 year. Available by prescription only, with a REMS (Risk Evaluation and Mitigation Strategy) program. Manufactured by Amgen. Not a controlled substance.

Frequently Asked Questions

What is Romiplostim?

A peptibody (peptide-Fc fusion protein) thrombopoietin receptor agonist that stimulates platelet production, FDA-approved for chronic immune thrombocytopenia in patients with insufficient response to other treatments.

What are the main uses of Romiplostim?

The primary research applications of Romiplostim include: FDA-approved treatment of chronic ITP in adults with insufficient response to corticosteroids, immunoglobulins, or splenectomy; FDA-approved for pediatric ITP patients aged 1 year and older with insufficient response to prior therapy; Reduction of concurrent ITP medication doses (steroid-sparing effect); Pre-procedural platelet count elevation in ITP patients requiring surgery; Investigated for other thrombocytopenic conditions (MDS, chemotherapy-induced, aplastic anemia); Research into thrombopoietin receptor agonist biology.

What are the risks and side effects of Romiplostim?

Documented risks and side effects include: Rebound thrombocytopenia after discontinuation, with platelet counts potentially dropping below baseline; gradual tapering recommended.; Bone marrow reticulin fibrosis observed in some patients; periodic monitoring with blood smears recommended.; Thrombotic/thromboembolic events (DVT, PE, stroke) reported, likely related to platelet count elevation; target platelet count should avoid excessive levels.; Headache, fatigue, arthralgia, and dizziness reported as common side effects.; Risk of progression to myelodysplastic syndrome or acute myeloid leukemia in patients with MDS treated with romiplostim (not approved for this indication).. Always consult a healthcare professional before considering any peptide.

Is Romiplostim legal?

FDA-approved prescription medication marketed as Nplate. Approved for chronic ITP in adults and children ≥1 year. Available by prescription only, with a REMS (Risk Evaluation and Mitigation Strategy) program. Manufactured by Amgen. Not a controlled substance.

How is Romiplostim administered?

Administered as weekly subcutaneous injection. Starting dose: 1 mcg/kg based on actual body weight. Dose adjusted by 1 mcg/kg per week to achieve platelet count ≥50,000/μL while avoiding excessive counts. Maximum dose: 10 mcg/kg/week. Platelet counts monitored weekly during dose adjustment and monthly once stable. Reconstituted from lyophilized powder before injection.

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The information on this page is for educational and informational purposes only. It is not intended as medical advice. Always consult a qualified healthcare professional before considering any peptide or supplement. 50 Best Limited does not endorse, recommend, or promote the use of any peptide for self-administration. Read our full disclaimer.

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