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Generic name: abemaciclib (a BEM a SYE klib)
Brand name: Verzenio
Dosage forms: oral tablet (100 mg; 150 mg; 200 mg; 50 mg)
Drug class: CDK 4 / 6 inhibitors

Medically reviewed by on Sep 6, 2021. Written by Cerner Multum.

What is abemaciclib?

Abemaciclib is used to treat advanced hormone-related breast cancer. Abemaciclib is used for this condition only if your tumor tests negative for a protein called human epidermal growth factor receptor 2 (HER2). HER2 protein can speed the growth of cancer cells.

Abemaciclib is sometimes given with other cancer medicines.

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


Abemaciclib can cause severe diarrhea, which can lead to dehydration or infection. Call your doctor right away if you have diarrhea. Drink extra fluids and start taking anti-diarrhea medicine such as loperamide (Imodium).

Abemaciclib can cause blood clots, liver problems, or serious and sometimes fatal infections. Call your doctor right away if you have symptoms such as: fever, chills, easy bruising or bleeding, unusual tiredness, loss of appetite, right-sided upper stomach pain, chest pain, shortness of breath, rapid breathing, fast heartbeats, or pain or swelling in your arms or legs.

Before taking this medicine

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

Tell your doctor if you have ever had:

  • a fever, chills, or other signs of infection; or

  • liver or kidney disease.

You may need to have a negative pregnancy test before starting this treatment.

Using abemaciclib during pregnancy could harm the unborn baby. Use effective birth control to prevent pregnancy while you are using abemaciclib and for at least 3 weeks after your treatment ends. Tell your doctor right away if you become pregnant during this time.

You should not breastfeed while using this medicine and for at least 3 weeks after your last dose.

How should I take abemaciclib?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Take the medicine at the same time each day, with or without food.

Swallow the tablet whole and do not crush, chew, or break it.

If you vomit shortly after taking abemaciclib, do not take another dose. Wait until your next scheduled dose time to take the medicine again.

Drink plenty of liquids while you are taking abemaciclib.

Abemaciclib can cause severe diarrhea, which can be life-threatening if it leads to dehydration or infection.

If you have diarrhea while taking abemaciclib: start taking anti-diarrhea medicine such as loperamide (Imodium) to quickly treat diarrhea. Drink extra fluids and call your doctor.

Abemaciclib 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 of these tests.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

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 taking abemaciclib?

Grapefruit may interact with abemaciclib and lead to unwanted side effects. Avoid the use of grapefruit products.

Abemaciclib 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.

Call your doctor at once if you have:

  • severe or ongoing diarrhea;

  • pain or burning when you urinate;

  • liver problems--right-sided upper stomach pain, loss of appetite, easy bruising or bleeding, feeling very tired;

  • low blood cell counts--fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath;

  • signs of inflammation in the lungs--new or worsening cough, painful or difficult breathing, wheezing, feeling short of breath even while resting; or

  • signs of a blood clot--pain or swelling in an arm or leg, chest pain, fast heartbeats, feeling short of breath.

Your cancer treatments may be delayed or permanently discontinued if you have certain side effects.

Common side effects may include:

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.

Abemaciclib dosing information

Usual Adult Dose for Breast Cancer:

150 mg orally 2 times a day

200 mg orally 2 times a day

Duration of Therapy: Until disease progression or unacceptable toxicity

-If using this drug in combination with fulvestrant on pre/perimenopausal women, treat these patients with a gonadotropin-releasing hormone agonist according to current clinical practice standards.
-When used in combination with this drug, the recommended dose of fulvestrant is 500 mg on Days 1, 15, and 29, then once monthly thereafter; refer to the manufacturer product information for fulvestrant.

-In combination with an aromatase inhibitor as initial endocrine-based therapy for postmenopausal women with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer
-In combination with fulvestrant for women with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer with disease progression following endocrine therapy
-As monotherapy for adult patients with HR-positive, HER2-negative advanced or metastatic breast cancer with disease progression following endocrine therapy and prior chemotherapy in the metastatic setting

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What other drugs will affect abemaciclib?

Sometimes it is not safe to use certain medications at the same time. Some drugs can affect your blood levels of other drugs you take, which may increase side effects or make the medications less effective.

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may affect abemaciclib, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Frequently asked questions

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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.