Pharmacology · Thrombopoietin receptor agonists
Eltrombopag !
An oral thrombopoietin receptor agonist for immune thrombocytopenia and severe aplastic anaemia. It can harm the liver and binds calcium and iron.
Updated 2026-11-01
Mechanism of action
Eltrombopag is a small non-peptide molecule that binds the transmembrane domain of the thrombopoietin receptor (MPL). It activates the receptor's signalling without competing with natural thrombopoietin, increasing megakaryocyte growth and platelet production.
- Eltrombopag enters the membrane part of MPL
- The receptor signals without thrombopoietin
- Megakaryocytes release more platelets
Pharmacokinetics
- Absorption
- Oral; absorption falls sharply with calcium, iron, magnesium, aluminium, zinc or selenium
- Elimination
- Mainly in faeces
- Half-life
- Long (about a day or more)
Indications
- Chronic immune thrombocytopenia with inadequate response to other treatments Immune thrombocytopenia (ITP) →
- Severe aplastic anaemia (first-line, together with immunosuppression) Aplastic anaemia →
- Thrombocytopenia in chronic hepatitis C, to allow interferon-based treatment
Adverse effects
Common
- Headache
- Cough, fever, tiredness
Contraindications
- Caution in liver disease, previous thrombosis, cataract and myelodysplastic syndrome
- Pregnancy (contraception is advised)
Key interactions
- Antacids and supplements with calcium, aluminium, magnesium, iron, zinc or selenium; dairy foods
- Chelation blocks absorption; eltrombopag is taken hours apart from them
- Interferon and ribavirin (hepatitis C)
- Higher risk of hepatic decompensation
What is monitored
- Liver function tests before and during treatment
- Platelet count
- Signs of thrombosis
Administration and safety
- Oral, once daily, separated by hours from calcium-rich foods, antacids and mineral supplements
- Lower starting doses for people of East or Southeast Asian ancestry and for those with liver impairment
Nursing care
- Teach the timing with respect to dairy, antacids and supplements
- Teach the signs of liver injury and when to report them
- Bleeding precautions continue while platelets recover
Pregnancy and breastfeeding
Pregnancy is avoided during treatment and for a short time after; effective contraception is advised and breastfeeding is avoided.
Test yourself
Think of the answer, then tap the question to see it.
Where on the receptor does eltrombopag bind?
The transmembrane domain of MPL.
Which organ must be monitored?
The liver (hepatotoxicity).
Why is it separated from milk and antacids?
Calcium and other polyvalent cations chelate it and block absorption.
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: Eltrombopag: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); 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).
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