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[Pharmacology](https://durgical.com/en/pharmacology/) · Class

# Thrombopoietin receptor agonists

Drugs that switch on the thrombopoietin receptor so the marrow makes more platelets, used mainly in chronic immune thrombocytopenia.

Updated 2026-11-01

## What they are

Romiplostim (a peptide on an antibody fragment, injected weekly) and eltrombopag (an oral small molecule) stimulate megakaryocytes. They are used when immune thrombocytopenia responds poorly to other treatments; eltrombopag is also used in severe aplastic anaemia and hepatitis C-related thrombocytopenia. The goal is a safe platelet count, not a normal one.

## Mechanism of action

They activate MPL, the thrombopoietin receptor, on megakaryocyte progenitors, increasing megakaryocyte growth and platelet production. Romiplostim binds the extracellular part of the receptor; eltrombopag binds its transmembrane domain.

Target: Thrombopoietin receptor (MPL)

## Key points

- Main use: chronic immune thrombocytopenia with inadequate response to steroids, immunoglobulin or splenectomy
- Risk of thrombosis, including portal vein thrombosis in advanced liver disease
- Eltrombopag: hepatotoxicity; avoid taking it with calcium, iron, magnesium or aluminium products
- Platelets fall again if treatment stops

## Drugs in this class

- [**Romiplostim** A weekly injected thrombopoietin receptor agonist (a peptide on an antibody fragment) that raises platelets in chronic… Thrombopoietin receptor (MPL, c-Mpl) on megakaryocytes](https://durgical.com/en/pharmacology/romiplostim/)
- [**Eltrombopag** An oral thrombopoietin receptor agonist for immune thrombocytopenia and severe aplastic anaemia. It can harm the liver… Thrombopoietin receptor (MPL, c-Mpl) on megakaryocytes](https://durgical.com/en/pharmacology/eltrombopag/)

## Others in the class

- avatrombopag
- lusutrombopag

## Test yourself

Think of the answer, then tap the question to see it.

## Which receptor do these drugs activate?

MPL, the thrombopoietin receptor.

## Which one is oral?

Eltrombopag (romiplostim is a weekly subcutaneous injection).

## Is the target a normal platelet count?

No; a count that lowers the bleeding risk.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: 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); [Romiplostim Injection: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a609008.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [Eltrombopag: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a609011.html) (MedlinePlus (U.S. National Library of Medicine), 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/classes/thrombopoietin-receptor-agonists/