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Generic name: romiplostim
Brand name: Nplate
Dosage form: subcutaneous injection
Drug class: Platelet-stimulating agents

Medically reviewed by Carmen Pope, BPharm. Last updated on Jul 7, 2024.

What is romiplostim?

Romiplostim (Nplate) stimulates thrombopoietin (TPO) production and may be used to treat low blood platelet counts (thrombocytopenia) in adults and children aged 1 year and older with immune thrombocytopenia (ITP) when certain medicines or surgery to remove the spleen have not worked well enough.

Romiplostim works by mimicking the action of natural TPO, which is a hormone produced by your liver and kidneys that regulates how many platelets you produce. Romiplostim's mechanism of action is to bind to and activate the same receptors that naturally occurring TPO uses to increase platelet production. This helps your body to make more platelets, which are cells that help your blood clot. Romiplostim is a TPO receptor agonist.

Romiplostim was FDA-approved on August 22, 2008, under the brand name Nplate. There is no generic Nplate available.   

What is romiplostim used for?

Romiplostim is an injectable prescription medicine administered by a healthcare provider that may be used to treat low blood platelet counts (thrombocytopenia) in:

Romiplostim may also used to treat adults and children including newborns exposed to high levels of radiation (acute radiation syndrome). The effectiveness of romiplostim for this use was only studied in animals because it could not be studied in people.

What are the side effects of romiplostim?

The most common side effects of romiplostim in adults include:

The most common side effects of romiplostim in children 1 year of age and older include:

Serious side effects and warnings

Romiplostim can cause serious side effects, including:

Worsening of a precancerous blood condition to a blood cancer (leukemia). Romiplostim is not for use in people with a precancerous condition called myelodysplastic syndromes (MDS), or for any condition other than immune thrombocytopenia (ITP). If you have MDS and receive romiplostim, your MDS condition may worsen and become acute leukemia. If MDS worsens to become acute leukemia you may die sooner from the acute leukemia.

Higher risk for blood clots. You may have a higher risk of getting a blood clot if your platelet count becomes high during treatment with romiplostim. You may have severe complications or die from some forms of blood clots, such as clots that spread to the lungs or that cause heart attacks or strokes.

Injection of too much romiplostim may cause a dangerous increase in your blood platelet count and serious side effects. Your healthcare provider may change your dose or stop romiplostim depending upon the change in your blood platelet count. You must have blood platelet counts done before you start, during, and after romiplostim therapy is stopped (see “How should I receive romiplostim?” below).

People who take romiplostim may have an increased risk of developing new or worsening changes in the bone marrow called “increased reticulin”. These changes may improve if you stop taking romiplostim. Your healthcare provider may need to check your bone marrow for this problem during treatment with romiplostim.

This is not a complete list of side effects. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects to Amgen at 1-800-77-AMGEN (1-800-772-6436).

Before taking

Do not use romiplostim if you have a precancerous condition called myelodysplastic syndrome (MDS), or low platelet count caused by any condition other than ITP.

Before receiving romiplostim, tell your healthcare provider about all of your medical conditions, including if you:

It is not known if romiplostim is safe and effective in children under the age of 1.


Romiplostim may harm your unborn baby. Tell your healthcare provider if you become pregnant or think you may be pregnant during treatment with romiplostim.


Romiplostim may pass into your breast milk and harm your baby. Do not breastfeed during treatment with romiplostim.

How is romiplostim injection administered?

Romiplostim is administered by a healthcare provider as an injection under the skin (subcutaneous) once a week when used for ITP.

During treatment for ITP, your healthcare provider will check your platelet count every week and change your dose of romiplostim as needed.

Romiplostim dosing

Recommended initial dose of romiplostim for adults and children with ITP

Recommended dose of romiplostim for adults and children acutely exposed to myelosuppressive doses of radiation

What happens if I miss a dose?

If you miss a scheduled dose of romiplostim, call your healthcare provider to schedule your next dose as soon as possible.

What should I avoid while receiving romiplostim?

Avoid situations or medicines that may increase your risk of bleeding.

What other drugs will affect romiplostim?

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal products.

Romiplostim may be used with other medical ITP therapies, such as corticosteroids, danazol, azathioprine, intravenous immunoglobulin (IVIG), and anti-D immunoglobulin.

Know the medicines you take. Keep a list of them and show it to your healthcare provider or pharmacist when you get a new medicine.


Store romiplostim vials in the refrigerator at 2°C to 8°C (36°F to 46°F) in the original carton to protect from light. Do not freeze.

Unopened romiplostim vials may be stored in the original carton at room temperature up to a maximum of 25°C (77°F) for a single period of up to 30 days.

Romiplostim injection ingredients

Active ingredient: romiplostim.

Inactive ingredients: L-histidine, mannitol, polysorbate 20, sucrose, and hydrochloric acid.

Romiplostim is a peptibody, which is a peptide fused to an antibody. It was the first fully engineered peptibody designed to stimulate platelet production.

Who makes romiplostim?

Amgen Inc. makes romiplostim under the brand name Nplate.

Popular FAQ

Nplate starts working from the first dose to increase platelet counts. Nplate works quickly to increase platelets. The median time to first platelet response was 2.1 weeks, according the the results of a single-arm, open-label study conducted in 75 adults with immune thrombocytopenia.

Nplate should be discontinued after 4 weeks of treatment at the maximum dose of 10 mcg/kg a week if platelet counts have not increased to sufficient levels. Continue reading

No, Nplate is not a chemotherapy (cancer) drug, it is a prescription medicine used to treat low platelet counts that can lead to bleeding in people with chronic immune thrombocytopenic purpura (ITP). Continue reading

Nplate (romiplostim) is a once-weekly subcutaneous injection that is administered by your healthcare provider and which is used to treat thrombocytopenia in certain patients with immune thrombocytopenia (ITP) who have not responded well enough to corticosteroids, immunoglobulins or splenectomy. Continue reading

Nplate (romiplostim) is a biological drug used to treat immune thrombocytopenia (ITP, low blood platelet counts) and increase survival in people exposed to high doses of radiation who have hematopoietic syndrome of acute radiation syndrome (HS-ARS) . Continue reading

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.