Nplate (romiplostim) is a brand-name drug prescribed for blood cell problems including immune thrombocytopenia (ITP). Nplate comes as a subcutaneous injection that’s typically given once a week by a healthcare professional.

Nplate is a biologic and belongs to a drug class called thrombopoietin receptor agonists. Nplate works by increasing the number of platelets in your blood. It isn’t available in a biosimilar version.

Keep reading for specific information about the dosage of Nplate, including its strengths and how to take the medication. For a comprehensive look at Nplate, see this article.

Note: This article describes typical dosages for Nplate provided by the drug’s manufacturer. However, your doctor will the prescribe the Nplate dosage that’s right for you.

Below is detailed information about Nplate dosages.

Nplate form

Nplate comes as a powder in single-dose vials. The powder is mixed with liquid to form a solution for subcutaneous injection. You’ll receive Nplate injections in a healthcare setting such as your doctor’s office.

Nplate strengths

Nplate comes in the following strengths:

  • 125 micrograms (mcg)
  • 250 mcg
  • 500 mcg

Typical dosages

The following information describes Nplate dosages that are commonly prescribed or recommended in adults. However, your doctor will determine the best dosage to fit your needs.

Dosage for immune thrombocytopenia

Nplate is prescribed to treat immune thrombocytopenia (ITP). For adults with ITP, the recommended initial dosage is 1 mcg of drug per kilogram* (mcg/kg) of body weight once per week.

After your first injection, your doctor will determine your weekly dosage based on your platelet levels. (A platelet is a type of blood cell that helps blood clot as usual.) To check your platelet levels, your doctor will have you take a platelet count test.

Typically, your dose will increase by 1 mcg/kg of body weight every week. This continues until your platelet count is more than 50,000 platelets per microliter (platelets/mcL) of blood. If your platelet count becomes too high, your doctor will decrease your dose. Sometimes, they need to skip a dose. They’ll monitor your platelet count weekly until it’s stable.

The maximum dose of Nplate is 10 mcg/kg of body weight per week.

The table below provides typical Nplate dosage recommendations by platelet count:

Platelet countDose adjustment
less than 50,000 platelets/mcLIncrease the dose by 1 mcg/kg of body weight.
200,000–400,000 platelets/mcL for 2 straight weeksDecrease the dose by 1 mcg/kg of body weight.
more than 400,000 platelets/mcLSkip the dose and monitor platelets every week. After platelets fall to less than 200,000/mcL, restart Nplate by decreasing the dose by 1 mcg/kg of body weight.

* For reference, 1 kg is about 2.2 pounds (lb).

Dosage for hematopoietic syndrome of acute radiation syndrome

Nplate is prescribed to treat hematopoietic syndrome of acute radiation syndrome. With this condition, radiation exposure leads to fewer red blood cells, white blood cells, and platelets. For adults, the typical dose is 10 mcg/kg of body weight. This is a single subcutaneous injection, given as soon as possible after radiation exposure.

Children’s dosage

Nplate treats ITP in children ages 1 year and older. It’s approved for ITP that’s been present at least 6 months. The drug is also approved to treat hematopoietic syndrome of acute radiation syndrome in children of any age. The dosage of Nplate for children with these conditions is the same as for adults. For details, see the “Typical dosages” section above.

If you have questions about your child’s Nplate dosage, talk with their doctor for more information.

Note: Your child’s doctor will calculate their Nplate dosage based on their platelet count and body weight. They’ll likely monitor your child’s body weight every 12 weeks.

Long-term treatment

Nplate is meant to be given as a long-term treatment for ITP. If you and your doctor determine that Nplate is safe and effective for you, you’ll likely receive the drug long term.

For treating hematopoietic syndrome of acute radiation syndrome, Nplate is typically given as a one-time dose.

Talk with your doctor if you have questions about your Nplate treatment.

The Nplate dosage your doctor prescribes will depend on several factors. These include:

  • the type and severity of the condition you’re taking Nplate to treat
  • your platelet levels
  • your body weight

If you have questions about your dosage, talk with your doctor for more information.

Your doctor gives Nplate as a subcutaneous injection. You’ll receive your doses at a healthcare setting, such as your doctor’s office or hospital. Your doctor will inject the drug at one of the recommended injection sites, which include the:

  • stomach
  • upper arm
  • thigh

If you’d like to know more about how Nplate is given, talk with your doctor.

If you miss an appointment for receiving your Nplate dose, call your doctor’s office right away. They’ll reschedule your appointment.

To help make sure that you don’t miss an appointment, try using a reminder system. This can include creating an appointment reminder on your phone. Or, put a note where you’ll see it, such as on your bathroom mirror or bedside table. You could also download a reminder app on your phone.

The dosages in this article are typical dosages provided by the drug manufacturer. If your doctor recommends Nplate for you, they’ll prescribe the dosage that’s right for you. If you have questions about the dosage of Nplate that’s best for you, talk with your doctor.

Besides learning about dosage, you may want other information about Nplate. These additional articles might be helpful:

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.