medicationsnplateNplate dosage

Nplate Dosage, forms & strengths

Jamie Winn, PharmD
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Medically reviewed by  Jamie Winn, PharmD

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Nplate (romiplostim) is an injectable thrombopoietin (TPO) receptor agonist that is manufactured by Amgen Inc. It is FDA-approved to treat thrombocytopenia (low platelet counts) in:

  • Adult patients with chronic immune thrombocytopenia (ITP) who did not respond to prior ITP treatments such as corticosteroids, immunoglobulins, or a splenectomy.
  • Pediatric patients 1 year and older with ITP for at least 6 months who did not respond to previous ITP treatments such as corticosteroids, immunoglobulins, or a splenectomy.
  • Adult and pediatric patients exposed to high doses of radiation.

What is Nplate’s mechanism of action?

Nplate is a thrombopoietin receptor agonist that works the same way as endogenous TPO does to help with the production of platelets. Platelets help your body form clots to heal injuries and prevent bleeding. Nplate is given to increase your platelet counts and reduce your risk of bleeding if you have a condition where the immune system attacks your platelets. This medication can also be used to improve platelet counts if you have acute radiation syndrome.

Nplate dosage forms and strengths

Nplate single-dose vial for injection in strengths of 125mcg, 250mcg, or 500mcg.

Nplate dosage

Adult and Pediatric Patients with ITP:

The initial dose of Nplate is 1 mcg/kg using your actual body weight. For adult patients, weekly dose adjustments will be made based on changes to their platelet counts only. For pediatric patients, weekly dose adjustments will be made based on changes to their platelet counts and body weight. Pediatric patients should have their body weight checked every 12 weeks. Your doctor can change the weekly dose of Nplate by 1 mcg/kg increments until your platelet count is ≥ 50 × 10^9/L. The maximum weekly dose of Nplate is 10 mcg/kg.

The dose of Nplate should be adjusted as follows:

  • If the platelet count is less than 50 × 10^9/L, the dose will be increased by 1 mcg/kg.
  • If the platelet count is between 200 × 10^9/L to 400 × 10^9/L for 2 consecutive weeks, the dose should be reduced by 1 mcg/kg.
  • If the platelet count is greater than 400 × 10^9/L, a dose should not be given.
  • The platelet count will be checked weekly and after it is less than 200 × 10^9/L, Nplate can be resumed at a dose reduced by 1 mcg/kg.

Adult and Pediatric Patients with Acute Radiation Syndrome:

The recommended dose of this medication is 10 mcg/kg given once as an injection under the skin. Nplate should be administered immediately after a suspected or confirmed exposure to radiation levels greater than 2 gray (Gy).

Nplate dosage restrictions

There are no guidelines or dose reduction recommendations available for patients with hepatic (liver) or renal (kidney) impairment.

How to take Nplate

  • Read the Patient Information, Prescribing Information, and Medication Guide that comes with this medication.
  • This medication is typically given as a subcutaneous injection by your healthcare provider once a week when treating chronic ITP. It is given as a one-time subcutaneous injection when treating exposure to high levels of radiation. Because the Nplate dose can be a very small volume, it should be administered with a syringe that contains 0.01 mL graduations.
  • Your doctor will perform baseline and weekly blood tests to monitor your platelet counts and change your weekly dose of Nplate if needed. After discontinuing Nplate, you will have blood tests for at least 2 weeks to make sure your platelet levels do not drop too low.
  • If you miss a dose of Nplate, call your doctor to reschedule right away.

Nplate dosage FAQs

What are some side effects of Nplate?

Some common side effects of Nplate that were seen in clinical trials when compared to placebo include:

  • Headache
  • Joint pain (arthralgia)
  • Dizziness
  • Abdominal pain
  • Indigestion (dyspepsia)
  • Insomnia
  • Tingling (paresthesia)
  • Shoulder pain
  • Inflammation of the sinuses (sinusitis)
  • Injection site reactions
  • Bruising (contusion)
  • Fever
  • Diarrhea
  • Oropharyngeal pain
  • Rash
  • Upper respiratory tract infections

Nplate can sometimes cause more serious side effects, including:

  • Severe, life-threatening hypersensitivity reactions (hives, swelling of your face or throat, and shortness of breath)
  • Progression from myelodysplastic syndromes (MDS) to acute myelogenous leukemia (AML)
  • Increased risk of bleeding with the discontinuation of Nplate
  • Bone marrow reticulin formation (fibrosis)
  • Thromboembolic complications such as portal vein thrombosis (blood clot)
  • Increased incidence of stroke and heart attacks
  • Formation of neutralizing antibodies and loss of response or failure to maintain platelet response
  • Purpura (blood vessel leak under the skin)
  • Anemia (low red blood cell count)

Contact your healthcare professional for medical advice about any adverse reactions you experience while taking Nplate. You can report your adverse effects to the FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

What are some drug interactions with Nplate?

The concomitant use of Nplate with other drugs can change how they work or increase the frequency and severity of side effects. You should ask your healthcare professional if any of the prescription drugs, over-the-counter medications, vitamins, and herbal supplements you take may interact with this medication.

Are there any contraindications for Nplate?

Nplate should not be used if you have had a serious allergic reaction to romiplostim or any inactive ingredients in its formulation.

What precautions are there with Nplate?

Before beginning Nplate for the treatment of thrombocytopenia or acute radiation syndrome, make sure your doctor is aware of your medical conditions, including:

  • Your spleen has been surgically removed
  • Blood cancer or myelodysplastic syndromes (MDS)
  • History of blood clots or other bleeding problems
  • Liver disease
  • Are pregnant, plan on becoming pregnant, or are breastfeeding

Is it safe to use Nplate while pregnant or breastfeeding?

Based on animal reproduction clinical studies, Nplate may cause harm to the fetus if used by pregnant women. There is no information available on whether this medication is found in breast milk during lactation. Breastfeeding is not recommended while taking Nplate. You should always discuss the risks and benefits of any medication with your healthcare provider if you are pregnant, plan on becoming pregnant, or are breastfeeding.

What foods should you avoid if you have thrombocytopenia?

While there are no placebo-controlled studies that show specific foods improve or boost a low platelet count, certain types of diets may help ease immune thrombocytopenia’s (ITP) symptoms. You should eat more fresh vegetables, fruits, whole grains, nuts, legumes, healthy fats, and leafy greens. You should reduce or avoid white flour, white rice, processed foods, trans fats, sugar, dairy products, and alcohol. You should also stay away from foods that interfere with blood clottings such as blueberries, tomatoes, red/purple grapes, garlic, onions, ginger, and ginseng.

How often is Nplate given?

Nplate is given as a subcutaneous injection once weekly. Your doctor will perform a complete blood count (CBC), including a platelet count every week, and change your dose of Nplate if needed.

Where do you inject Nplate?

Before administering Nplate, reconstitution with sterile water for injection is necessary. If your calculated dose is less than 23 mcg, additional dilution to its final concentration with 0.9% Sodium Chloride is required. Your doctor will then inject Nplate under the skin in the middle of your thigh, your stomach (not within 2 inches of your belly button), or the outer area of your upper arms.

What is the average price of Nplate?

Currently, no generic Nplate available and the brand name is extremely expensive. The average cost of 4 vials of Nplate 500 mcg is over $28,000.

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The content on this website is intended for information purposes only. It does not constitute medical advice. The information on this website should not be relied upon and is not a substitute for professional medical advice. You should always speak to your doctor regarding the risks and benefits of any treatment.