Pacritinib is a JAK2/FLT3 inhibitor used to treat bone marrow fibrosis, with a standard dose of 200mg per dose, taken orally twice daily. In terms of efficacy, the drug can significantly improve spleen volume and symptom scores, especially for patients with thrombocytopenia. Attention should be paid to adverse reactions such as liver toxicity, bleeding risk, and QT interval prolongation. Relevant indicators should be monitored regularly during medication.

1. Usage and dosage

(1) Standard dose: 200mg orally, twice daily, on an empty stomach or with food.

(2) Dose adjustment: When grade 3 or above adverse reactions occur, the administration should be suspended and reduced to 100mg/dose after recovery; Grade 4 toxicity requires permanent discontinuation of medication.

(3) Special population: Individuals with moderate to severe liver dysfunction need to reduce their dosage by 50%; Patients with renal insufficiency do not need to adjust the dosage.

2 Clinical efficacy

(1) Spleen reaction: About 29% of patients had a spleen volume reduction of ≥ 35% after 24 weeks of treatment.

(2) Symptom improvement: The proportion of cases where the total symptom score decreased by ≥ 50% reached 25%.

(3) Hematological advantages: It can still be safely used for patients with baseline platelet count<50 × 10 ⁹/L.

3 Precautions

(1) Bleeding risk: Platelets<50 × 10 ⁹/L should be corrected before treatment, and should not be used in cases of active bleeding.

(2) Cardiotoxicity: baseline QTc>480ms is prohibited, and regular monitoring of electrocardiogram is required during treatment.

(3) Hepatotoxicity: Monthly monitoring of liver function is required, and medication should be suspended when ALT/AST>3 times ULN.

(4) Infection risk: may increase the likelihood of opportunistic infections, and it is necessary to monitor for viral infections such as herpes zoster.

(5) Drug interactions: Avoid using potent CYP3A4 inhibitors/inducers in combination.