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Why is this medication prescribed?

Pacritinib is used to treat adults with certain types of myelofibrosis (MF; a cancer of the bone marrow in which the bone marrow is replaced by scar tissue and causes decreased blood cell production). Pacritinib is in a class of medications called kinase inhibitors. It works by blocking the action of the abnormal protein that signals cancer cells to multiply. This helps stop or slow the spread of cancer cells.

How should this medicine be used?

Pacritinib comes as a capsule to take by mouth. It is usually taken twice a day, with or without food. Take pacritinib at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take pacritinib exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the capsules whole; do not open, chew, or crush them.

Your doctor will order blood tests before and during your treatment to see how you are affected by this medication. Your doctor may increase or decrease your dose of pacritinib during your treatment, or may tell you to stop taking pacritinib temporarily or permanently. This depends on how well the medication works for you, your lab test results, and if you experience side effects. Talk to your doctor about how you are feeling during your treatment.

Ask your pharmacist or doctor for a copy of the manufacturer's information for the patient.

Other uses for this medicine

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

What special precautions should I follow?

Before taking pacritinib,

  • tell your doctor and pharmacist if you are allergic to pacritinib, any other medications, or any of the ingredients in pacritinib capsules. Ask your pharmacist for a list of the ingredients.
  • tell your doctor if you are taking apalutamide (Erleada), carbamazepine (Carbatrol, Epitol, Tegretol, Teril), ceritinib (Zykadia), clarithromycin, enzalutamide (Xtandi), idelalisib (Zydelig), itraconazole (Sporanox, Tolsura), ketoconazole, nefazodone, nelfinavir (Viracept), phenytoin (Phenytek), ribociclib (Kisqali), rifampin (Rifadin, Rimactane), ritonavir (Norvir, in Kaletra), saquinavir, tucatinib (Tukysa), and voriconazole (Vfend). Your doctor will probably tell you not to take pacritinib if you are taking one or more of these medications. Many other medications may also interact with pacritinib, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
  • tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Be sure to mention any of the following: aprepitant (Emend), crizotinib (Xalkori), digoxin (Lanoxin), diltiazem (Cardizem, Cartia, Taztia, Tiazac) efavirenz (Sustiva, in Atripla, Symfi Lo), erythromycin, fluconazole (Diflucan), phenobarbital, and verapamil (Calan, Verelan). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with pacritinib, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
  • tell your doctor if you smoke or if you have ever smoked, if you often get any type of infection or if you think you may have any type of infection now, or if you have diarrhea or often have loose stools. Also tell your doctor if you have or have ever had cancer, bleeding problems, low blood levels of potassium, a heart attack or other heart problems, a stroke, a blood clot in your legs or lungs, high cholesterol, high blood pressure, diabetes, or liver problems.
  • tell your doctor if you are pregnant or plan to become pregnant. If you become pregnant while taking pacritinib, call your doctor.
  • tell your doctor if you are breastfeeding. You should not breastfeed while you are taking pacritinib and for 2 weeks after your final dose.
  • you should know that this medication may decrease fertility in men. Talk to your doctor about the risks of taking pacritinib.
  • tell your doctor if you have recently had surgery or if you plan to have surgery, including dental surgery. If you are scheduled to have surgery, your doctor will stop your treatment with pacritinib 7 days before the surgery.
  • you should know that pacritinib often causes diarrhea, which can be severe. Your doctor will probably tell you to drink plenty of liquids and to take anti-diarrhea medication to prevent dehydration (loss of too much water from your body) when you first experience diarrhea or loose stools. Call your doctor immediately if you experience any of the following symptoms of dehydration: extreme thirst, dry mouth or skin, decreased urination, or fast heartbeat.

What special dietary instructions should I follow?

Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medication.

What should I do if I forget a dose?

Skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What side effects can this medication cause?

Pacritinib may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • nausea
  • vomiting
  • swelling of the hands, feet, ankles, or lower legs

Some side effects can be serious. If you experience any of these symptoms or those listed in the SPECIAL PRECAUTIONS section, call your doctor immediately or get emergency medical treatment:

  • nosebleeds or bleeding from your gums; coughing up or vomiting blood or material that looks like coffee grounds; unusual bleeding or bruising; increased menstrual flow or vaginal bleeding; pink, red, or dark brown urine; or red or tarry black bowel movements
  • lightheadedness, fainting, or irregular heartbeat
  • crushing chest pain or chest heaviness; pain in the arms, back, neck, jaw, or stomach; or breaking out in cold sweat
  • shortness of breath or difficulty breathing
  • slow or difficult speech; sudden weakness or numbness of the face, arm or leg; sudden headache; sudden vision problems; or sudden difficulty walking
  • swelling, pain, tenderness, warmth or redness in one or both legs
  • shortness of breath, coughing up blood, fast heartbeat, fast breathing, pain when breathing deeply
  • fever, chills, cough, painful or frequent urination, sores or blisters on the skin, or other signs of infection
  • shortness of breath, fast heartbeat, headache, dizziness, pale skin, confusion, or tiredness

Pacritinib may increase your risk of developing other cancers, such as lymphoma (cancer that begins in the cells that fight infection). Talk to your doctor about the risks of receiving this medication.

Pacritinib may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from light, excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach.

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website ( for more information if you do not have access to a take-back program.

In case of emergency/overdose

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include:

  • nausea
  • vomiting
  • diarrhea
  • blurred vision
  • dizziness
  • unusual bleeding or bruising
  • fever, chills, or other signs of infection

What other information should I know?

Keep all appointments with your doctor and the laboratory.

Before having any laboratory test, tell your doctor and the laboratory personnel that you are taking pacritinib.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

Brand names

  • Vonjo®
Last Revised - 06/15/2022