Momelotinib is a kinase inhibitor indicated for the treatment of adult patients with intermediate- or high-risk primary or secondary myelofibrosis who have anemia. As a potent prescription medication, understanding its potential adverse reactions and mandatory precautions is crucial to ensuring the efficacy of treatment.

Adverse Reactions of Momelotinib

Common Adverse Reactions

1. Thrombocytopenia

2. Bleeding

3. Bacterial infection

4. Fatigue

5. Dizziness

Serious Adverse Reactions

Risk of Infection

Patients receiving momelotinib treatment may develop severe infections, including bacterial and viral infections (e.g., COVID-19), which can be fatal.

Momelotinib should not be initiated in patients with active infections prior to the start of treatment.

Patients with a history of chronic hepatitis B virus (HBV) infection may be at risk of HBV reactivation when taking Janus kinase (JAK) inhibitors, including momelotinib. Physicians will test relevant indicators before treatment.

Thrombocytopenia and Neutropenia

Momelotinib can cause new-onset or worsening thrombocytopenia and neutropenia.

New or worsened thrombocytopenia (platelet count < 50×10⁹/L) has been observed in 20% of patients.

Severe neutropenia occurs in 2% of patients. These conditions increase the risk of bleeding and infection, respectively.

Precautions for Momelotinib

Dosage and Administration

Recommended dosage: The recommended dosage for adults is 200 mg orally once daily, with or without food.

Dosage adjustment for hepatic impairment: For patients with severe hepatic impairment, the recommended starting dosage is 150 mg orally once daily.

Management of missed dose: If a dose is missed, take the next scheduled dose on the following day as planned. Do not take a double dose on the same day to make up for the missed dose.

Administration method: Tablets must be swallowed whole. Do not split, crush or chew the tablets.

Monitoring Before and During Treatment

Hematological monitoring: Perform complete blood count testing before the initiation of treatment and periodically during treatment, with a focus on platelet and neutrophil counts.

Hepatic function monitoring: Monitor transaminase and bilirubin levels before treatment, once monthly for the first 6 months after treatment initiation, and then periodically as clinically indicated.

Hepatitis B screening: For patients at risk of chronic hepatitis B infection, test HBV serology before the start of treatment.