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Generic name: omacetaxine [ OH-ma-se-TAX-een ]
Brand name: Synribo
Dosage form: subcutaneous powder for injection (3.5 mg)
Drug class: Miscellaneous antineoplastics

Medically reviewed by on Nov 28, 2022. Written by Cerner Multum.

What is omacetaxine?

Omacetaxine is used to treat chronic myeloid leukemia (CML).

Omacetaxine is given after at least two other cancer treatments did not work or have stopped working.

Omacetaxine may also be used for purposes not listed in this medication guide.

Omacetaxine side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Omacetaxine may cause serious side effects. Call your doctor at once if you have:

  • ongoing nausea, stomach pain, or diarrhea;

  • easy bruising, unusual bleeding (nose, mouth, vagina, or rectum);

  • confusion, vision changes, slurred speech;

  • blood in your urine, bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds;

  • severe skin rash or itching;

  • low red blood cells (anemia)--pale skin, unusual tiredness, feeling light-headed or short of breath, cold hands and feet;

  • high blood sugar--increased thirst, increased urination, dry mouth, fruity breath odor; or

  • signs of infection--fever, chills, tiredness, body aches, feeling short of breath.

Common side effects of omacetaxine may include:

  • fever, low blood cell counts;

  • feeling weak or tired;

  • diarrhea;

  • nausea; or

  • pain, swelling, or redness where the medicine was injected.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Omacetaxine can increase your risk of bleeding or infection. Call your doctor if you have unusual bruising or bleeding, blood in your urine or stools, confusion, problems with vision or speech, or new signs of infection (fever, chills, tiredness, body aches, feeling short of breath).

Before taking this medicine

You should not use omacetaxine if you are allergic to it.

Tell your doctor if you have ever had:

  • diabetes (in you or a family member); or

  • bleeding problems.

Omacetaxine can harm an unborn baby or cause birth defects if the mother or the father is using omacetaxine.

  • If you are a woman, do not use omacetaxine if you are pregnant. You may need to have a negative pregnancy test before starting this treatment. Use effective birth control to prevent pregnancy while you are using this medicine and for at least 6 months after your last dose.

  • If you are a man, use effective birth control if your sex partner is able to get pregnant. Keep using birth control for at least 3 months after your last dose.

  • Tell your doctor right away if a pregnancy occurs while either the mother or the father is using omacetaxine.

This medicine may affect fertility (ability to have children) in men. However, it is important to use birth control to prevent pregnancy because omacetaxine can harm an unborn baby.

Do not breastfeed while using this medicine, and for at least 2 weeks after your last dose.

How is omacetaxine given?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Omacetaxine is injected under the skin. A healthcare provider may teach you how to properly use the medication by yourself.

Omacetaxine is usually given every 12 hours. Do not change your dosing schedule or stop using this medicine unless your doctor tells you to.

Your healthcare provider will show you where on your body to inject omacetaxine. Use a different place each time you give an injection. Do not inject into the same place two times in a row.

Your injection will be prepared at the pharmacy and you will receive the medicine in prefilled syringes. Store these syringes in the refrigerator, do not freeze. If you need to transport the medicine, place the syringes in a cooler with ice packs.

Do not allow this medicine to come into contact with food or drinks inside your refrigerator.

The omacetaxine mixture does not contain a preservative. You must use a prefilled syringe within 6 days of when it was mixed at the pharmacy.

If a prefilled syringe reaches room temperature, you must use it within 12 hours after it was mixed.

Each vial (bottle) is for one use only. Throw it away after one use, even if there is still medicine left inside.

If this medicine accidentally gets on your skin, wash it thoroughly with soap and warm water. Anyone handling this medicine or giving you an injection should wear protective gloves and safety glasses.

Use a needle and syringe only once and then place them in a puncture-proof "sharps" container. Follow state or local laws about how to dispose of this container. Keep it out of the reach of children and pets.

If you need surgery or dental work, tell the surgeon ahead of time that you are using omacetaxine. You may need to stop using the medicine for a short time.

Omacetaxine can lower blood cells that help your body fight infections and help your blood to clot. Your blood will need to be tested often. Your cancer treatments may be delayed based on the results.

Omacetaxine dosing information

Usual Adult Dose for Chronic Myelogenous Leukemia:

Induction dose: 1.25 mg/m2 subcutaneously twice daily for 14 consecutive days of a 28 day cycle.

Maintenance dose: 1.25 mg/m2 subcutaneously twice daily for 7 consecutive days of a 28 day cycle.

Use: Chronic or accelerated phase CML with resistance and/or intolerance to two or more tyrosine kinase inhibitors.

Comments: There are no trials verifying an improvement in disease-related symptoms or increased survival with omacetaxine.

What happens if I miss a dose?

Skip the missed dose and use your next dose at the regular time. Do not use two doses at one time.

If you are receiving omacetaxine in a clinic or cancer center, call your doctor for instructions if you miss an appointment for your omacetaxine injection.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using omacetaxine?

If this medication gets in your eyes, rinse with water and call your doctor right away.

Avoid being near people who are sick or have infections. Tell your doctor at once if you develop signs of infection. Avoid activities that may increase your risk of bleeding or injury. Use extra care to prevent bleeding while shaving or brushing your teeth.

Avoid driving or hazardous activity until you know how omacetaxine will affect you. Your reactions could be impaired.

What other drugs will affect omacetaxine?

Other drugs may affect omacetaxine, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.