How it is administered

Pacritinib is administered orally in the form of capsules. Each capsule contains 100 mg of pacritinib (as pacritinib citrate). The recommended dose is 200 mg taken by mouth twice daily, with or without food. The capsules should be swallowed whole and not opened, broken, or chewed.

How it works

Pacritinib is a type of medication known as a kinase inhibitor. It works by blocking specific enzymes in the body called kinases, particularly Janus associated kinase 2 (JAK2), mutant JAK2V617F, FLT3, and IRAK1. These kinases are involved in the signaling pathways that regulate blood cell production and immune function. In certain blood cancers, like myelofibrosis, these pathways become overactive, leading to abnormal growth of blood cells and symptoms such as an enlarged spleen.

By inhibiting these kinases, pacritinib helps to reduce the abnormal signaling, which can decrease the size of the spleen and improve symptoms related to blood cancers. Importantly, pacritinib does not significantly inhibit JAK1, which may reduce some side effects compared to other kinase inhibitors.

Who Should take it

Pacritinib is indicated for adults with intermediate or high-risk primary or secondary myelofibrosis (a type of blood cancer), especially those with a low platelet count (below 50 × 10^9/L). Myelofibrosis can occur on its own or as a result of other conditions like polycythemia vera or essential thrombocythemia.

Patients who have symptoms such as an enlarged spleen, anemia, or other complications from myelofibrosis and who have not responded to or cannot tolerate other treatments may benefit from pacritinib. Your healthcare provider will determine if pacritinib is appropriate based on your specific blood counts and overall health.

Who should not take it

Pacritinib should not be taken by patients who are currently using strong CYP3A4 inhibitors or inducers, as these can significantly alter the levels of pacritinib in the body, increasing the risk of side effects or reducing its effectiveness.

It should also be avoided in patients with active bleeding, those with a baseline QTc interval above 480 msec (a heart rhythm measure), and those who have unresolved serious infections. Always inform your healthcare provider about all medications you are taking and any medical conditions you have before starting pacritinib.

Commonly used with

Pacritinib may be used alone for the treatment of myelofibrosis, especially in patients with low platelet counts. In clinical trials, it was compared to other therapies such as ruxolitinib, hydroxyurea, glucocorticoids, erythropoietic agents, immunomodulatory agents, and others, but it is not typically combined with these medications.

Your healthcare provider will decide if pacritinib should be used alone or in combination with other supportive treatments based on your individual needs.

Commonly tested with

In clinical studies, pacritinib was tested against a variety of other treatments for myelofibrosis, including ruxolitinib, hydroxyurea, glucocorticoids, erythropoietic agents, immunomodulatory agents, mercaptopurine, danazol, interferons, cytarabine, and melphalan. These studies helped to determine the effectiveness and safety of pacritinib compared to other available therapies.

It is important to note that pacritinib should not be used with strong CYP3A4 inhibitors or inducers, as these can affect how the medication works.