Romiplostim is an injectable medicine that stimulates the body to produce more platelets, the blood cells responsible for clotting. It belongs to a class of medicines called thrombopoietin receptor agonists, used to treat chronic immune thrombocytopenia (ITP), a condition where the immune system destroys platelets faster than the body can replace them. It is a prescription-only, healthcare-provider-administered medicine

• Therapeutic Class: Platelet-stimulating agent.

• Pharmacological Class: Thrombopoietin (TPO) receptor agonist.

• Drug Family: Peptibody (peptide-Fc fusion protein) TPO receptor agonists.

• ATC Classification: B02BX04 (Romiplostim).

Approved: Primary immune thrombocytopenia (ITP) in adult patients who are refractory to other treatments (e.g., corticosteroids, immunoglobulins); also approved for pediatric patients 1 year and older with ITP for at least 6 months who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy; and to improve survival in adults and children with hematopoietic syndrome of acute radiation syndrome (a specific radiation-injury indication).

Commonly used for: Adults and children with chronic ITP whose platelet counts remain low despite standard treatments, needing an ongoing option to reduce bleeding risk.

Off-label use (only under medical guidance): Sometimes explored for other causes of thrombocytopenia under specialist guidance, though it is specifically not indicated for thrombocytopenia due to myelodysplastic syndrome.

• Injection (subcutaneous, lyophilized powder for reconstitution): available in 250 mcg and 500 mcg single-use vials.

Romiplostim attaches to the thrombopoietin receptor on bone marrow cells, mimicking the action of the body's natural hormone (thrombopoietin) that stimulates platelet production. This signals the bone marrow to produce more platelet-forming cells (megakaryocytes), increasing the number of platelets released into the bloodstream, helping counteract the excess platelet destruction seen in ITP.

• Standard starting dose (adults): 1 mcg/kg based on actual body weight, given as a weekly subcutaneous injection, adjusted in increments of 1 mcg/kg (up to a maximum of 10 mcg/kg weekly) until a platelet count of at least 50 x 10^9/L is achieved.

• Condition-wise dose (pediatric, 1 year and older): Same starting dose of 1 mcg/kg based on actual body weight, weekly, with dose adjustments in 1 mcg/kg increments; body weight reassessed every 12 weeks.

• Route: Subcutaneous injection, administered by a healthcare provider once weekly.

• Missed dose: Rescheduled by the treating clinical team; not self-timed by the patient without guidance.

• Overdose: May cause excessively high platelet counts, increasing clotting risk; managed by dose withholding and close monitoring.

• Common: Headache, fatigue, joint pain (arthralgia), bruising, and dizziness.

• Serious: Bone marrow fibrosis (reticulin deposition, which may improve if treatment is stopped), worsening of thrombocytopenia and bleeding after stopping the medicine (a rebound effect), increased risk of blood clots, and, in patients with myelodysplastic syndrome, a risk of disease progression to acute myeloid leukaemia (not an approved use).

• Emergency symptoms: Signs of a blood clot (leg swelling/pain, chest pain, sudden shortness of breath), unusual or severe bruising/bleeding, or signs of a severe allergic reaction.

• Recovery advice: Weekly platelet count monitoring during dose adjustment allows the lowest effective dose to be used, reducing the risk of overshooting platelet counts; platelet counts are also checked for several weeks after stopping treatment given the rebound bleeding risk.

• Pregnancy: Used only if clearly needed, under medical supervision, as data are limited.

• Breastfeeding: Advised against breastfeeding during treatment, due to the potential for serious adverse reactions in a breastfed child from IgG components of the medicine.

• Liver disease: Used with caution and monitoring.

• Kidney disease: Used with caution and monitoring.

• Elderly: Used with routine monitoring; no specific age-based dose adjustment beyond general precautions.

• Children: Approved for ITP in children 1 year and older who have had an insufficient response to standard therapies.

• Other thrombopoietin receptor agonists (e.g., eltrombopag): not combined with romiplostim.

• Anticoagulants/antiplatelet medicines: increased platelet counts alongside blood-thinning medicines requires attention to overall clotting risk balance.

• ITP medicines being tapered (e.g., corticosteroids): as romiplostim raises platelet counts, doses of other ITP medicines may be reduced under medical guidance, rather than representing a drug interaction to avoid.

• Complete blood counts, including platelet counts, weekly during the dose adjustment phase, then monthly once a stable dose is established.

• Platelet counts for at least 2 weeks after discontinuation, given rebound thrombocytopenia risk.

• Peripheral blood smear periodically to check for bone marrow abnormalities.

• Monitoring for signs of blood clots throughout treatment.

Eltrombopag, Avatrombopag (other thrombopoietin receptor agonists, given orally); Rituximab, immunosuppressive agents, or splenectomy (other approaches for refractory chronic ITP).

Generally used as a standalone platelet-stimulating therapy in patients refractory to first-line ITP treatments; not combined with other thrombopoietin receptor agonists.

• Immune Thrombocytopenia (ITP) Medicines

• Thrombopoietin Receptor Agonists

• Pediatric Hematology Treatments

1. Low Platelet Count (Thrombocytopenia): Symptoms, Causes, Diagnosis, and Treatment

2. How Romiplostim Works for Chemo-Induced Thrombocytopenia

3. Signs Of Low Haemoglobin You Should Know

• https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/125268s163lbl.pdf

• https://www.fda.gov/drugs/fda-approves-romiplostim-pediatric-patients-immune-thrombocytopenia

The information on this page is for educational purposes only and is not a substitute for medical advice. Please consult your doctor to know if this treatment is appropriate for your condition.