Nplate (Romiplostim) for Immune Thrombocytopenia

Nplate (romiplostim) is a prescription medication approved by the U.S. Food and Drug Administration (FDA) to treat low platelet counts in adults and children ages 1 and older with immune thrombocytopenia (ITP).

How Nplate Works and How It’s Taken

Nplate is a type of medicine called a thrombopoietin receptor agonist. It works on the thrombopoietin receptor, which helps the body make more platelets. Platelets are blood cells that help stop bleeding.

Doctors prescribe Nplate for adults and children ages 1 and older when certain ITP treatments have not worked well enough. These treatments include corticosteroids, immunoglobulins, or surgery to remove the spleen. For children, Nplate is used only if they have had ITP for at least six months.

In ITP, platelet counts are too low. Nplate helps raise platelet counts enough to lower the risk of bleeding.

Nplate is given as an injection under the skin by a healthcare provider.

Typical Dosing for ITP

Starting dose — The recommended starting dose is 1 microgram per kilogram once a week as an injection under the skin.
Dose adjustments — The doctor checks platelet counts during treatment and may change the dose by 1 microgram per kilogram at a time.
Maximum dose — The dose should not exceed 10 micrograms per kilogram once a week.
High platelet counts — If platelet counts get too high, the doctor may lower the dose or hold it. After a held dose, the doctor may restart Nplate at a lower dose once platelet counts have fallen enough.
Stopping treatment — If platelet counts do not rise enough to help prevent clinically important bleeding after four weeks at the highest weekly dose, the doctor will stop Nplate.

This information is based on prescribing information, but your healthcare provider may tailor your treatment plan. Always follow their guidance.

Nplate Side Effects

In clinical studies of Nplate for ITP, common side effects occurred in about 5 percent to 41 percent of adults and children taking Nplate, depending on the age group and side effect.

In adults, side effects included:

Headache
Arthralgia (joint pain)
Dizziness
Insomnia (trouble sleeping)
Myalgia (muscle pain)
Pain in the arms or legs
Shoulder pain
Abdominal pain
Dyspepsia (indigestion)
Paresthesia (tingling or numbness in the hands or feet)

In children ages 1 and older with ITP, the most common side effects were:

Contusion (bruising)
Upper respiratory tract infection, such as a cold
Oropharyngeal pain (pain in the mouth or throat)

Serious Side Effects and Warnings

Nplate can cause serious side effects that may require immediate medical attention. These include:

Thrombotic or thromboembolic complications — Blood clots can occur in the legs, lungs, liver veins, heart, or brain, potentially causing a heart attack or stroke.
Bone marrow changes — Increased reticulin or collagen fibers in the bone marrow can affect blood cell production.
Loss of response to Nplate — The medicine may stop raising platelet counts well enough, sometimes because of antibodies.
Progression of myelodysplastic syndromes (MDS) — In people with MDS, Nplate may increase the risk of progression to acute myeloid leukemia and death.

Get medical help right away if you think you are having a serious reaction.

How To Save on Nplate

Amgen, the manufacturer of Nplate, offers the Amgen SupportPlus Co-Pay Program. Eligible people with commercial or private insurance may pay as little as $0. The copay program is not valid for people whose Nplate is paid for in whole or in part by Medicare, Medicaid, or another federal or state healthcare program, or for people paying cash.

People with government insurance or no insurance can access information about other financial assistance options that may be available. Amgen SupportPlus also offers financial support resources and other patient support services.

To learn more, visit the Amgen SupportPlus Co-Pay Program or call 866-264-2778.

What To Know Before Taking Nplate

Before and during treatment with Nplate, your doctor will check your complete blood counts, including your platelet count.

Tell your doctor if you have any allergies to romiplostim or any ingredients in Nplate.

Tell your doctor about all medicines you take, including prescription drugs, over-the-counter medicines, vitamins, and herbal supplements.

Before receiving Nplate, tell your healthcare provider about all of your medical conditions. Tell them if you:

Have had surgery to remove your spleen
Have a bone marrow problem, including blood cancer or MDS
Have or have had a blood clot
Have chronic liver disease
Have bleeding problems

Nplate is also FDA-approved to increase survival in adults and children, including term newborns, who have been exposed to high levels of radiation that can damage the bone marrow (hematopoietic syndrome of acute radiation syndrome).

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

Tell your healthcare provider if you are pregnant or think you may be pregnant during treatment. Nplate may harm your baby if you are pregnant. Do not breastfeed during treatment with Nplate.

Community FAQs

These answers are fact-checked by our editorial staff.

How effective is Nplate for ITP?

In adult studies of Nplate for ITP, Nplate helped raise platelet counts. In one 24-week study of adults who had not had their spleen removed, 61 percent of people taking Nplate had a durable platelet response. This means their platelet counts stayed at a helpful level for a set amount of time.

By comparison, 5 percent of people taking placebo (an inactive treatment) had this response. In another 24-week study of adults who had their spleen removed, 38 percent of people taking Nplate had a durable platelet response, compared with no one taking placebo.

Overall platelet response rates were also higher with Nplate. The rates were 88 percent with Nplate versus 14 percent with placebo in one study and 79 percent with Nplate versus 0 percent with placebo in another study.

In a separate 12-month study, 93 percent of adults taking Nplate had a platelet response of at least 50 × 10⁹/L during treatment.

How long does Nplate take to work for ITP?

In clinical studies, platelet counts increased after Nplate, and the increase depended on the dose.

After a single dose of 1 to 10 micrograms per kilogram injected under the skin, peak platelet counts were seen over a two- to three-week period in people with ITP.

Nplate is given once a week as an injection under the skin. The doctor adjusts the dose based on the person’s platelet count.

What tests or monitoring are needed with Nplate for ITP?

Your doctor will check your complete blood count (CBC), which includes your platelet count.

During dose adjustment, these blood tests are done every week. After your dose is stable, the tests are done monthly.

If you stop Nplate, your doctor will check your blood counts every week for at least two weeks.

These tests help your doctor adjust your Nplate dose. The goal is to keep your platelet count high enough to help lower bleeding risk. Nplate is not used to make platelet counts normal.

Tell your doctor about any bruising or bleeding during treatment with Nplate.