Pharmacology · Thrombopoietin receptor agonists
Romiplostim !
A weekly injected thrombopoietin receptor agonist (a peptide on an antibody fragment) that raises platelets in chronic immune thrombocytopenia.
Updated 2026-11-01
The figure shows natural human thrombopoietin bound to its receptor MPL (cryo-EM); romiplostim's peptide binds the same receptor but has no sequence similarity to thrombopoietin.
Mechanism of action
Romiplostim is a peptide that binds the thrombopoietin receptor, joined to antibody fragments that prolong its half-life. Its peptide has no sequence similarity to thrombopoietin, so it does not induce antibodies against the natural hormone. Activation of MPL increases megakaryocyte growth and platelet production.
- Romiplostim binds MPL on megakaryocyte progenitors
- The receptor signals growth and maturation
- Megakaryocytes release more platelets
Pharmacokinetics
- Absorption
- Subcutaneous injection
- Elimination
- Cleared by the reticuloendothelial system
- Half-life
- Several days; longer when platelets are low
Indications
- Chronic immune thrombocytopenia with inadequate response to other treatments Immune thrombocytopenia (ITP) →
- Bone marrow injury from acute radiation exposure (haematopoietic syndrome)
Adverse effects
Common
- Headache, dizziness
- Joint, muscle and limb pain
- Tingling in arms or legs
- Trouble sleeping
Contraindications
- Hypersensitivity to romiplostim
- Caution in myelodysplastic syndrome, other marrow diseases and liver disease
Key interactions
- Anticoagulants and antiplatelets
- Bleeding risk persists while platelets are low; the combination needs close review
What is monitored
- Platelet count regularly
- Complete blood count after stopping
- Signs of thrombosis
Administration and safety
- Weekly subcutaneous injection, usually by a health professional
- The dose is adjusted to the platelet response; a missed appointment is reported at once
Nursing care
- Check the platelet count before each dose
- Teach bleeding precautions and to avoid injury
- Warn that platelets can fall if doses are missed or treatment stops
Pregnancy and breastfeeding
Data in pregnancy are limited; breastfeeding is avoided during treatment.
Test yourself
Think of the answer, then tap the question to see it.
What is romiplostim made of?
A thrombopoietin-receptor-binding peptide joined to antibody fragments.
How is it given?
By subcutaneous injection once a week.
What can happen if it is stopped?
Platelets fall again, with a risk of bleeding.
Related drugs
Related conditions
← Back to the class: Thrombopoietin receptor agonists
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Romiplostim Injection: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2025); Farmacología básica y clínica (Katzung), 16.ª ed., cap. 33 (McGraw Hill, 2025); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 45 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.