Romiplostim

Pronunciation: pronunciation varies by local usage.

Generic name: romiplostim
Brand names: Nplate
Drug class: Thrombopoietin receptor agonist
Form: Single-dose vials (125 mcg, 250 mcg, 500 mcg)
Route: Subcutaneous injection
Legal status: Prescription-only biologic medicine

Availability and supply rules vary by country

Trade names by country: United States · Canada

What romiplostim is and how it works

Romiplostim is a thrombopoietin receptor agonist that stimulates platelet production. It is used to increase platelet counts in certain conditions. (1)

It is indicated for adults and children with immune thrombocytopenia (ITP) who have had an insufficient response to other treatments or splenectomy, and for hematopoietic syndrome of acute radiation syndrome. It is injected subcutaneously by a healthcare provider. It is not a cure for ITP; after stopping, platelet counts may fall below pre-treatment levels and require monitoring.

Mechanism of action: how romiplostim works

Romiplostim is a thrombopoietin receptor agonist that stimulates platelet production by activating the thrombopoietin receptor. (1)

What romiplostim is used for

Immune thrombocytopenia (ITP) in adults

For adults with ITP who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. (1)

ITP in children (1 year and older)

For children aged 1 year and older with ITP for at least 6 months who have had an insufficient response to other treatments or splenectomy. (1)

Hematopoietic syndrome of acute radiation syndrome

For adults and children (including newborns) with suspected or confirmed exposure to high doses of radiation. (1)

Before taking romiplostim

Do not take / not appropriate for

Do not receive romiplostim after a severe hypersensitivity reaction to romiplostim or any ingredient. (all products) (1)
Do not use romiplostim to normalize platelet counts or for thrombocytopenia from causes other than ITP (e.g., myelodysplastic syndrome). (all indications) (1)

Tell your clinician about

Any previous hypersensitivity or anaphylactic reactions to romiplostim or other biologics.
If you have liver disease, a history of blood clots, or any condition that increases clotting risk.
All current medications, especially anticoagulants (blood thinners), antiplatelet drugs, or other ITP treatments.
If pregnant, planning pregnancy, or breastfeeding — romiplostim may harm an unborn baby and is not recommended during breastfeeding.
Any signs of unusual bleeding or clotting.

(1)

How to take romiplostim

Romiplostim is injected under the skin by a healthcare provider. The dose is calculated based on body weight and platelet count and adjusted weekly.
Do not self-inject. Home administration is not described in the US label.
Do not change the dose or frequency unless directed by the clinician.

(1)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1)

Missed dose

If a scheduled dose is missed, contact the healthcare provider for rescheduling instructions.

Overdose

The US label does not provide specific overdose information. If a dosing error is suspected, seek prompt medical evaluation. Overdose may cause excessive platelet increases and thrombotic risk. (1)

Side effects

Side effects can vary by indication and age. The most common effects in adults with ITP include joint pain, dizziness, and muscle pain. In children, bruising and upper respiratory infections are common. Serious risks include blood clots and worsening thrombocytopenia after stopping.

Arthralgia (joint pain)

What to notice: Pain in joints, reported in 26% of adults in clinical trials.

What to do: Report to the healthcare provider if pain is persistent or severe. (1)

Dizziness and insomnia

What to notice: Dizziness (17%) and trouble sleeping (16%).

What to do: Discuss with the clinician if these symptoms are troublesome. (1)

Myalgia and pain in extremities

What to notice: Muscle pain (14%) and limb pain (13%).

What to do: Inform the treatment team if symptoms persist or worsen. (1)

Contusion and upper respiratory infections (pediatric)

What to notice: Bruising (41%) and cold-like symptoms (31%) in children.

What to do: Monitor and report to the prescriber if severe or frequent. (1)

Thrombotic/thromboembolic complications

What to notice: Signs of a blood clot such as leg swelling, pain, redness, chest pain, shortness of breath, or stroke symptoms (e.g., weakness, vision changes, confusion).

What to do: Seek immediate medical attention. (1)

Worsening thrombocytopenia after discontinuation

What to notice: Increased bruising, bleeding gums, nosebleeds, or unusual bleeding after stopping treatment.

What to do: Contact the clinician; platelet counts should be monitored. (1)

Serious warnings

Thrombotic/thromboembolic complications — emergency

Symptoms: Leg swelling, pain, redness (deep vein thrombosis); chest pain, shortness of breath (pulmonary embolism); heart attack symptoms; stroke symptoms (sudden numbness, confusion, trouble seeing, severe headache).

Action: Seek emergency medical care immediately. (1)

Worsening thrombocytopenia after discontinuation — urgent

Symptoms: Bruising, petechiae, bleeding gums, nosebleeds, or any unusual bleeding after stopping romiplostim.

Action: Contact the clinician promptly; platelet counts should be checked. (1)

Bone marrow reticulin fiber formation — urgent

Symptoms: May be asymptomatic; detected through blood tests and bone marrow examination. Signs could include worsening blood counts or new symptoms.

Action: Report any new or worsening symptoms to the prescriber. (1)

Loss of platelet response — urgent

Symptoms: Platelet counts stop responding to romiplostim; may be due to neutralizing antibodies. This may be detected on routine blood monitoring.

Action: The clinician will investigate if platelet counts do not improve with appropriate dose adjustments. (1)

Progression of myelodysplastic syndrome (MDS) — urgent

Symptoms: If romiplostim is used in MDS (off-label), it can increase blast cells and risk of acute myeloid leukemia. Symptoms may include fatigue, infection, bleeding.

Action: Romiplostim is not recommended for MDS; if used, hematologic monitoring is essential. (1)

Interactions

Medicine or test	Effect	Action
Anticoagulants and antiplatelet medicines	No formal interaction studies were conducted. Romiplostim raises platelet counts, so there is a potential increased risk of bleeding or thrombosis when used with medications that affect coagulation.	Provide the care team with a complete medicine list. Platelet counts will be monitored, and doses may be adjusted. (1)
Other ITP therapies (corticosteroids, immunoglobulins)	Romiplostim may be used with these treatments. The clinician may continue, reduce, or stop them based on platelet response.	Follow the clinician's guidance on tapering or adjusting other ITP medications. (1)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Romiplostim may harm an unborn baby. It should be used during pregnancy only if the potential benefit justifies the potential risk. Clinicians and patients must discuss. (1)

Breastfeeding

The US label advises not to breastfeed during treatment with romiplostim. (1)

Children

Romiplostim is indicated for children aged 1 year and older with ITP for at least 6 months. Pediatric dosing follows the same weight-based, platelet-adjusted schedule as adults. (1)

Chronic liver disease

Portal vein thrombosis has been reported in patients with chronic liver disease. Use with caution and monitor closely. (1)

Monitoring

Before starting

Confirm the diagnosis of ITP and exclude other causes of thrombocytopenia (e.g., MDS).
Obtain baseline platelet count and assess bleeding risk.
Evaluate for any history of thrombosis or liver disease.
Weigh the patient to calculate the initial dose.

During treatment

Monitor platelet counts weekly and adjust dose to maintain a count of at least 50 × 10^9/L as needed to reduce bleeding risk; the clinician skips that week’s dose when the count is above 400 × 10^9/L.
Assess for signs of thrombosis, especially during rapid platelet increases.
Evaluate for loss of response or development of neutralizing antibodies if platelet counts do not improve.
Periodic bone marrow examinations may be considered to monitor for reticulin fibrosis.

(1)

Storage

Vials should be refrigerated at 2–8°C in the original carton to protect from light; do not freeze. Unopened vials may be kept at room temperature (up to 25°C) for a single period of up to 30 days. Handled by healthcare professionals.

Professional information

Clinician-facing context only. Use the current local indication and dosing tables.

United States

Indication: ITP – adults and children

Dose summary: Initial: 1 mcg/kg subcutaneously once weekly. Adjust by 1 mcg/kg weekly to achieve platelet count ≥50 × 10^9/L; maximum 10 mcg/kg weekly. The clinician skips the weekly dose when platelets exceed 400 × 10^9/L and lowers it by 1 mcg/kg when 200–400 × 10^9/L persists for two consecutive weeks. The clinician ends treatment when there is no adequate response after 4 weeks at the maximum dose.

Renal context: No specific renal or hepatic dosing adjustments are described in the US label. (1)

United States

Indication: Acute radiation syndrome

Dose summary: 10 mcg/kg subcutaneously as a single dose, as soon as possible after suspected or confirmed exposure.

Renal context: No specific adjustments. (1)

Mechanism of action

Hepatic guidance

Portal vein thrombosis has been reported in patients with chronic liver disease. No specific dose adjustments are provided for hepatic impairment; use with caution.

Overdose note

The US label does not describe specific overdose management. Medication errors may cause excessive platelet increases and thromboembolic events; supportive care and platelet monitoring are advised. (1)

Frequently asked questions

Is romiplostim a cure for ITP?

No. It raises platelet counts while used. After stopping, thrombocytopenia can return and may be worse than before treatment, so platelet counts will be monitored. (1)

Why do I need weekly blood tests?

The dose is adjusted based on your platelet count to keep it at a safe level (≥50 × 10^9/L) and to avoid it getting too high (≥400 × 10^9/L). (1)

Can I inject romiplostim at home?

The US label only describes administration by a healthcare provider. Self-injection or home use is not recommended without specific authorization and training, which are not covered in the label. (1)

What symptoms need urgent medical attention?

Seek emergency care for signs of a blood clot (leg swelling/pain, chest pain, shortness of breath, stroke symptoms) or unusual bleeding/bruising after stopping treatment. (1)

What is the mechanism of action of romiplostim?

Romiplostim is a thrombopoietin receptor agonist that stimulates platelet production by activating the thrombopoietin receptor. (1)

What is the generic name of Romiplostim?

The generic name is romiplostim. It is sold under brand names including Nplate. (1)

What class of drug is romiplostim?

Romiplostim is classed as: Thrombopoietin receptor agonist. (1)

References

NPLATE (romiplostim) for injection — prescribing informationU.S. Food and Drug Administration · United States · dated 2025-03 · accessed 2026-08-08 · source 1
NPLATE (ROMIPLOSTIM) INJECTION, POWDER, LYOPHILIZED, FOR SOLUTION [AMGEN, INC] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 2
Romiplostim Injection — patient drug information (MedlinePlus)U.S. National Library of Medicine (MedlinePlus) · US · accessed 2026-08-14 · source 3
Nplate — FDA approval record (Drugs@FDA BLA125268)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 4
romiplostim — RxNorm normalized drug concept (RXCUI 805452)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 5

Brand names by country

Single-ingredient romiplostim names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

Nplate500 ug/mL, 125 ug/.25mL, 250 ug/.5mL · amgen, inc

Canada

NPLATE

View brands in additional countries.