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Nplate: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on May 23, 2022.

1. How it works

  • Nplate is a brand (trade) name for romiplostim which is a synthetic (man-made) protein that may be used in the treatment of chronic immune thrombocytopenic purpura (ITP) or acute radiation syndrome.
  • Nplate works by stimulating your bone marrow to make more platelets. It does this by binding directly to and activating the TPO receptor, in a similar way to naturally occurring TPO (thrombopoietin), which is the substance that controls the number of platelets the body makes. Activation of the TPO receptor increases megakaryocyte progenitor proliferation and platelet production. In people with ITP, the amount of TPO is not high enough. Boosting platelet production helps lower the risk of bleeding.
  • Nplate belongs to the class of medicines known as thrombopoietin receptor agonists.

2. Upsides

  • May be used to treat adults with ITP who have not had a good response to corticosteroids, immunoglobulins, or removal of their spleen (splenectomy).
  • May be used to treat ITP of at least 6 months duration in children aged 1 year and older who have not had a good response to corticosteroids, immunoglobulins, or removal of their spleen (splenectomy).
  • Can increase survival in adults and children (including full-term newborn babies) who have been acutely exposed to bone marrow suppressing doses of radiation. The dose is 10mcg/kg administered once after the suspected radiation greater than 2 gray (Gy).
  • The objective is to keep the platelet count about 50,000 per microliter to lower the risk of bleeding. Use the lowest dose necessary and adjust the dose according to the response.
  • Works like TPO and tells the body to make more platelets.
  • May be used in adults and children who are at least 1 year old.
  • Administered once a week as a subcutaneous injection. The prescribed dose may be very a very small volume (for example, 0.15mL); use a syringe that contains 0.01 graduations.
  • May be given in conjunction with other medical ITP treatments, such as corticosteroids, danazol, azathioprine, IV immunoglobulin, and anti-D immunoglobulin.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Joint pain, muscle pain, pain in the extremities, shoulder pain, dizziness, insomnia, abdominal pain, dyspepsia, paresthesias (abnormal sensations of the skin such as tingling, pricking, chilling, burning, or numbness) are the most common side effects reported. Bronchitis, sinusitis, vomiting, nausea, upper respiratory tract infection, cough, and diarrhea have also been reported. Children may be more likely to experience oropharyngeal pain, a rash, fever, contusions, peripheral swelling, or itch.
  • May cause thromboembolic complications as a result of increases in platelet counts. Portal vein thrombosis has been reported in people with chronic liver disease receiving Nplate.
  • May increase the risk for development or progression of reticulin fiber formation within the bone marrow. This usually improves when Nplate is stopped.
  • Does not treat low platelets (thrombocytopenia) caused by myelodysplastic syndrome (MDS) or any other cause other than ITP. Research has shown that there is a risk of progression of MDS to acute myelogenous leukemia with Nplate. Nplate is not indicated for the treatment of thrombocytopenia due to MDS.
  • Reserve use for patients whose platelet level and clinical condition increases the risk for bleeding.
  • The aim of Nplate is to keep the platelet count about 50,000 per microliter, not to normalize it. Trying to normalize it increases the risk of thromboembolic complications.
  • Research into using Nplate for acute radiation syndrome is limited to animals because it could not be studied in people.
  • Discontinue Nplate if after 4 weeks at the maximum dose (10mcg/kg) the platelet count does not increase to a level sufficient enough to avoid clinically important bleeding.
  • Perform laboratory monitoring, such as a complete blood count (CBC) (including platelets) weekly during the dosage adjustment phase of Nplate and then monthly following the establishment of a stable dose of Nplate. Continue CBCs weekly for at least 2 weeks following discontinuation of Nplate.
  • Neutralizing antibodies to Nplate may occur; consider these as a cause of low levels of responsiveness or failure to maintain a platelet response. Samples may be submitted to Amgen (1-800-772-6436) to detect antibody formation.
  • May cause fetal harm when administered to a pregnant woman. Advise women of reproductive potential not to become pregnant while being administered Nplate. There is no data about Nplate during breastfeeding, and women should be advised not to breastfeed during treatment with Nplate.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Nplate may be used to increase platelet counts above 50 x 109/L in adults and children with ITP who have not had a good response to corticosteroids, immunoglobulins, or removal of their spleen (splenectomy). It may also be used to treat acute radiation exposure (greater than 2 Gy). Side effects include pain, thromboembolic events, dizziness, insomnia, and dyspepsia.

5. Tips

  • Keep your scheduled appointments with your healthcare provider and you should read the medication guide associated with Nplate. Nplate is only indicated for people with ITP or those who have been exposed to excessive doses of radiation (above 2 Gy).
  • If you are being administered Nplate because you have been exposed to excessive doses of radiation, be aware that efficacy studies of Nplate for radiation could not be conducted in humans due to ethical reasons, so approval for this use was based on studies conducted in animals.
  • The goal of Nplate treatment for ITP is to keep platelet counts above 50 x 109/L to reduce the risk of bleeding, not to normalize platelet counts.
  • On discontinuation of Nplate, you may be at increased risk of bleeding or thrombocytopenia that is worse than that experienced during Nplate treatment. Monitor yourself for bleeding, and if you experience significant bleeding then contact your healthcare provider immediately. Avoid situations or medications that increase your risk of bleeding.
  • Nplate may cause other serious side effects, such as reticulin fiber formation within the bone marrow that may require further investigations, such as bone marrow examinations.
  • Your doctor will need to monitor your platelet counts and CBC weekly until a stable Nplate dose has been achieved, then monthly thereafter. When you discontinue Nplate, monitoring should be continued weekly for two weeks.
  • If you are a woman of childbearing age you should use adequate contraception to ensure you do not become pregnant while you are being administered Nplate. Do not breastfeed.

6. Response and effectiveness

  • Treatment with Nplate resulted in dose-dependent increases in platelet counts. After one dose of 1-10 mcg/kg Nplate in people with ITP the peak platelet count was 1.3 to 14.9 times greater than the baseline count over a 2 to 3-week period.
  • Platelet counts increased to above 50 x 109/L for seven out of eight patients with ITP who received six weekly doses of Nplate at 1 mcg/kg.
  • Another study showed a 4.7 to 7.3 fold increase in platelet count above baseline values in healthy adults administered a single dose of Nplate.
  • An overall platelet response of 88% was reported in a trial of nonsplenectomized patients who received 1 mcg/kg Nplate over 24 weeks, compared to only 14% with placebo. Only 20% required rescue therapy compared to 62% of those who received a placebo.
  • In another study of splenectomized patients, an overall platelet response rate of 79% was reported with Nplate treatment, compared to 0% with placebo.

7. Interactions

Medicines that interact with Nplate may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with Nplate. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

There is only 1 documented interaction with Nplate, which is:

  • carfilzomib (combination use increases the risk of dangerous blood clots).

Refer to the product information for Nplate for any new interactions.

References

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Nplate only for the indication prescribed.

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

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