Chinese drug instructions for use of Roprostim/Romigrastim

Romiplostim/Romiplostim The trade name isNplate, also known as Enpeban or AMG531. It is a recombinant protein-targeted drug that is a thrombopoietin receptor agonist (TPO-RA). It mainly simulates the binding of natural TPO to the receptor in the body, activates the c-Mpl pathway, promotes megakaryocyte proliferation and platelet production in the bone marrow, and is thus used to treat certain types of thrombocytopenia.

1. The scope of indications is clear, focusing on the treatment of immune diseases and radiation exposure.

Romigrastim is mainly approved for the following types of patients:

1. Chronic immune thrombocytopenia (ITP) : Applicable to adult patients who are ineffective in glucocorticoids, immune globulin or splenectomy, and pediatric ITP patients aged 1 year and above with a disease duration of ≥ 6 months.

2. Damage to hematopoietic function in acute radiation syndrome: used to improve the survival rate of adult and pediatric patients (including newborns) after receiving myelosuppressive doses of radiation.

It is important to note that romigrastim is not used for thrombocytopenia caused by myelodysplastic syndrome (MDS), nor for the purpose of normalizing platelet counts. It should only be used when there is a real risk of bleeding.

2. The main method of administration is subcutaneous injection, and the dosage can be adjusted individually.

InITP treatment, the recommended initial dose of romiplostim is 1mcg/kg, injected subcutaneously once a week. Dose adjustments for adult patients are based on changes in platelet count, with the goal of maintaining ≥50 × 10⁹/L to reduce the risk of bleeding, up to a maximum of 10 mcg/kg. The dose is adjusted by increasing or decreasing 1mcg/kg each time. If the platelet count is >200×10⁹/L for two consecutive weeks, the dose needs to be reduced. If the platelet count exceeds 400×10⁹/L, the medication should be suspended and re-evaluated.

For pediatric patients, in addition to initial dosing based on body weight, body weight also needs to be reassessed every 12 weeks to guide dose adjustment. In clinical practice, the common median effective dose in pediatrics is approximately 5.5mcg/kg.

In the setting of acute radiation syndrome, the recommended dose is10mcg/kg as a single subcutaneous injection, administered as soon as possible after confirmed or suspected exposure to ≥2 Gy of radiation. There is no need to wait for confirmation of blood indicators in such cases.

3. Types of adverse reactions and prevention concerns

Common side effects of romiplostim include bronchitis, sinusitis, vomiting, headache, joint pain, myalgia, nausea, oropharyngeal pain, dizziness and upper respiratory tract infection, etc. Most of them are mild to moderate symptoms. Regardless of the duration of ITP, the overall tolerance is good, but some patients may experience a decrease in platelet rebound.

4. Drug storage and stability assurance strategies

Romigrastim is a freeze-dried powder, which should be placed in the original packaging. Store refrigerated at 2-8°C, avoiding light and freezing. If stored at room temperature for a short period of time (≤25°C), it should not exceed 30 days and should not be refrigerated again.

Precautions for storage after reconstitution are as follows:

1. If only water for injection is added to reconstitute, store at room temperature for up to 4 hours or refrigerate for no more than 24 hours;

2. If further diluted (such as with physiological saline), it can be stored in the syringe at room temperature or refrigerated for up to 4 hours;

3. All products must be stored away from light and shaking is strictly prohibited to prevent protein inactivation.

5. Guidelines for treatment adjustment and discontinuation

If there is no significant increase in platelets after using the maximum dose (10mcg/kg/week) for 4 weeks, it is recommended to discontinue the drug and consider other treatments. CBC (blood routine) needs to be monitored weekly during treatment. After the dose is stable, it can be changed to monthly review. Continue to monitor platelet levels for at least 2 weeks after stopping the drug to prevent another sudden drop.

Reference materials:https://en.wikipedia.org/wiki/Romiplostim