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Jakavi (Ruxolitinib phosphate) Information

Jakavi, which contains the active ingredient ruxolitinib phosphate, is a targeted therapy classified as a JAK (Janus Kinase) inhibitor. It is primarily used to treat adults with myelofibrosis, including primary myelofibrosis, post-polycythemia vera myelofibrosis, and post-essential thrombocythemia myelofibrosis. Your doctor may also prescribe this medicine for the treatment of polycythemia vera in patients who have not responded to or cannot tolerate hydroxyurea, as well as for certain types of graft-versus-host disease (GvHD). By managing these conditions, Jakavi helps reduce the size of an enlarged spleen and improves systemic symptoms such as fever, night sweats, and bone pain. The medication is taken by mouth as a tablet, typically twice daily.

The mechanism of action involves the selective inhibition of the Janus Kinases JAK1 and JAK2. These enzymes mediate signaling by cytokines and growth factors that are important for hematopoiesis (blood cell production) and immune function. In patients with myelofibrosis and polycythemia vera, JAK signaling becomes overactive, leading to the excessive production of blood cells and inflammatory markers. By blocking these specific enzymes, Jakavi helps normalize blood cell production and reduces the inflammatory processes that cause splenomegaly and other debilitating symptoms.

Jakavi Side Effects

Jakavi is generally well tolerated, but common side effects may occur as your body adjusts to the medication. Commonly reported effects include dizziness, headache, tiredness, and bruising or bleeding more easily than usual. Because of its impact on blood cell production, many patients experience anemia (low red blood cells), thrombocytopenia (low platelets), or neutropenia (low white blood cells). Some patients may also experience weight gain or increased cholesterol levels.

More serious side effects can occur and require immediate medical attention. Stop taking the medication and seek help if you experience:
• Blood Clots: Sudden swelling or pain in a leg or arm, chest pain, or shortness of breath (signs of deep vein thrombosis or pulmonary embolism).
• Heart Events: Shortness of breath, dizziness, or chest discomfort, which may indicate serious cardiovascular issues.
• Severe Bleeding: Unusual bleeding from the gums, blood in the stool or urine, or coughing up blood.
• Severe Infections: Fever, chills, or persistent sore throat. Jakavi increases the risk of Herpes Zoster (shingles) and reactivation of Hepatitis B or Tuberculosis.
• Skin Cancer Changes: New skin lesions or changes in the appearance of existing moles.

Jakavi Precautions

Do not use Jakavi if you are allergic to ruxolitinib or any other ingredients in the tablet. Before starting treatment, inform your doctor of your complete medical history, especially if you have kidney or liver disease, a history of tuberculosis, hepatitis B, or skin cancer. You should also inform your doctor if you have any heart problems or a history of tobacco use, as these may increase the risk of serious side effects.

Tell your doctor about all medications you take, as Jakavi has significant interactions. The levels of Jakavi in your blood can be increased by specific strong CYP3A4 inhibitors, such as some antifungal medications (e.g., ketoconazole) or certain antibiotics (e.g., clarithromycin). If you are taking these, your doctor may need to adjust your dose. You should avoid eating grapefruit or drinking grapefruit juice while taking Jakavi, as it can interfere with how your body processes the drug. Additionally, let your doctor know if you take any other medications that affect your blood counts or immune system.

Inform your doctor if you are pregnant, planning to become pregnant, breastfeeding, or planning to breastfeed. Jakavi should only be used during pregnancy if the potential benefit justifies the risk to the fetus, as animal studies have shown potential harm. Avoid breastfeeding during treatment and for two weeks after your final dose, as it is unknown if the drug passes into breast milk and could harm the infant.

Take Jakavi exactly as prescribed, with or without food. It is vital that you do not stop taking Jakavi suddenly without consulting your doctor, as this can cause a rapid return of symptoms or a "withdrawal" effect. If you miss a dose, do not take an extra one. Wait for your next scheduled dose. Store the tablets at room temperature, away from moisture and heat, and keep them out of reach of children.

Do I need a prescription to order Jakavi?

Yes, a prescription is required from your physician to order Jakavi.