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Generic name: omacetaxine
Brand name: Synribo
Dosage form: subcutaneous powder for injection (3.5 mg)
Drug class: Miscellaneous antineoplastics

Medically reviewed by  A Ras MD.

What is omacetaxine used for?

Omacetaxine is a prescription medicine that is used to treat a type of leukemia.


SYNRIBO contains the active ingredient omacetaxine mepesuccinate, a cephalotaxine ester. It is a protein synthesis inhibitor. Omacetaxine mepesuccinate is prepared by a semi-synthetic process from cephalotaxine, an extract from the leaves of Cephalotaxus sp. The chemical name of omacetaxine mepesuccinate is cephalotaxine, 4-methyl (2R)-hydroxyl-2-(4-hydroxyl-4-methylpentyl) butanedioate (ester).

Omacetaxine mepesuccinate has the following chemical structure:

Chemical Structure

The molecular formula is C29H39NO9 with a molecular weight of 545.6 g/mol. SYNRIBO for Injection is a sterile, preservative-free, white to off-white, lyophilized powder in a single-dose vial. Each vial contains 3.5 mg omacetaxine mepesuccinate, 60 mg hydrochloric acid for drug substance solubilization, 10 mg mannitol as a bulking agent, and hydrochloric acid and sodium bicarbonate to adjust pH to 6.

SYNRIBO is intended for subcutaneous administration after reconstitution with 1.0 mL of 0.9% Sodium Chloride Injection, USP. The pH of the reconstituted solution is between 5.5 and 7.0.

Mechanism of Action

The mechanism of action of omacetaxine mepesuccinate has not been fully elucidated but includes inhibition of protein synthesis and is independent of direct Bcr-Abl binding. Omacetaxine mepesuccinate binds to the A-site cleft in the peptidyl-transferase center of the large ribosomal subunit from a strain of archaeabacteria. In vitro, omacetaxine mepesuccinate reduced protein levels of the Bcr-Abl oncoprotein and Mcl-1, an anti-apoptotic Bcl-2 family member. Omacetaxine mepesuccinate showed activity in mouse models of wild-type and T315I mutated Bcr-Abl CML.

Before taking omacetaxine, tell your doctor:

  • If you are allergic to omacetaxine; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
  • If you have high blood sugar (diabetes).
  • If you are breast-feeding. Do not breast-feed while you take omacetaxine and for 2 weeks after your last dose.

This is not a list of all drugs or health problems that interact with omacetaxine.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take omacetaxine with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take omacetaxine?

  • Tell all of your health care providers that you take omacetaxine. This includes your doctors, nurses, pharmacists, and dentists.
  • Avoid driving and doing other tasks or actions that call for you to be alert until you see how omacetaxine affects you.
  • Have blood work checked as you have been told by the doctor. Talk with the doctor.
  • This medicine may lower the ability of your bone marrow to make blood cells that your body needs. This can lead to needing a blood transfusion and very bad and sometimes deadly bleeding problems or infections. Tell your doctor right away if you have signs of infection like fever, chills, or sore throat; any bruising or bleeding; or if you feel very tired or weak.
  • You may bleed more easily. Be careful and avoid injury. Use a soft toothbrush and an electric razor.
  • You may have more chance of getting an infection. Wash hands often. Stay away from people with infections, colds, or flu.
  • If you have high blood sugar (diabetes), talk with your doctor. This medicine may raise blood sugar.
  • Check your blood sugar as you have been told by your doctor.
  • If you have upset stomach, throwing up, diarrhea, or are not hungry, talk with your doctor. There may be ways to lower these side effects.
  • This medicine may cause harm if swallowed. If omacetaxine is swallowed, call a doctor or poison control center right away.
  • If you are 65 or older, use omacetaxine with care. You could have more side effects.
  • This medicine may cause harm to an unborn baby. A pregnancy test will be done before you start omacetaxine to show that you are NOT pregnant.
  • Women must use birth control while taking omacetaxine and for some time after the last dose. Ask your doctor how long to use birth control. If you get pregnant, call your doctor right away.
  • Men with a partner who may get pregnant must use birth control while taking omacetaxine and for some time after the last dose. Ask your doctor how long to use birth control. If your partner gets pregnant, call the doctor right away.
  • This medicine may affect being able to father a child. Talk with the doctor.

How is omacetaxine best taken?

Use omacetaxine as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • It is given as a shot into the fatty part of the skin on the top of the thigh, belly area, or upper arm.
  • If you will be giving yourself the shot, your doctor or nurse will teach you how to give the shot.
  • Your pharmacist will need to mix omacetaxine before you get it.
  • You will need to take special care when handling omacetaxine. Check with the doctor or pharmacist to see how to handle omacetaxine.
  • Do not eat or drink anything while you handle omacetaxine. Use omacetaxine in an area away from food, children, and pregnant women.
  • Move the site where you give the shot with each shot.
  • Do not give into skin that is irritated, tender, bruised, red, scaly, hard, scarred, or has stretch marks.
  • Throw away needles in a needle/sharp disposal box. Do not reuse needles or other items. When the box is full, follow all local rules for getting rid of it. Talk with a doctor or pharmacist if you have any questions.
  • If you get omacetaxine on the skin, wash it off right away with soap and water.
  • If omacetaxine gets in the eyes, rinse with cool water.
  • If omacetaxine is spilled, you will need to clean it up in a special way. Check with the doctor or pharmacist if you are not sure how to clean it up.

What do I do if I miss a dose?

  • Skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.

What are the side effects of omacetaxine that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of infection like fever, chills, very bad sore throat, ear or sinus pain, cough, more sputum or change in color of sputum, pain with passing urine, mouth sores, or wound that will not heal.
  • Signs of bleeding like throwing up or coughing up blood; vomit that looks like coffee grounds; blood in the urine; black, red, or tarry stools; bleeding from the gums; abnormal vaginal bleeding; bruises without a cause or that get bigger; or bleeding you cannot stop.
  • Signs of high blood sugar like confusion, feeling sleepy, more thirst, more hungry, passing urine more often, flushing, fast breathing, or breath that smells like fruit.
  • Weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight.
  • Shortness of breath.
  • Swelling in the arms or legs.

What are some other side effects of omacetaxine?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Hair loss.
  • Constipation, diarrhea, stomach pain, upset stomach, throwing up, or feeling less hungry.
  • Headache.
  • Feeling tired or weak.
  • Back, muscle, or joint pain.
  • Pain in arms or legs.
  • Trouble sleeping.
  • Pain, redness, or swelling where the shot was given.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If overdose is suspected:

If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

How do I store and/or throw out omacetaxine?

  • Store at room temperature or in a refrigerator. Do not freeze.
  • If stored at room temperature, use within 12 hours from when it was mixed. If stored in a refrigerator, use within 6 days from when it was mixed. If stored in a refrigerator, keep away from food or drink.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.




  • NDC 63459-177-14 Rx only
  • Single-Dose Vial.
  • Discard unused portion.
  • Synribo® (omacetaxine mepesuccinate) for Injection
  • 3.5 mg/vial
  • For Subcutaneous Use Only
  • Must be Reconstituted Before Use
  • Medication Guide Required: Each time SYNRIBO is dispensed, give the patient a Medication Guide.
  • Distributed by:
  • Teva Pharmaceuticals USA, Inc.
  • Parsippany, NJ 07054
  • TEVA


Carton Label for Synribo



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