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Generic name: palbociclib
Brand name: Ibrance
Dosage form: tablet, capsule
Drug class: CDK 4/6 inhibitors

Medically reviewed by Melisa Puckey, BPharm. Last updated on Aug 23, 2023.

What is palbociclib?

Palbociclib is an oral medicine that is used to treat specific types of breast cancer in adults. Your doctor will prescribe it for you if it has a proven benefit for your type of cancer. 

It is used in combination with other cancer treatments, either aromatase inhibitor or fulvestrant, which one you use will depend on your clinical factors.  

It is a targeted therapy which blocks CDK4 and CDK6, which are enzymes in cells that are important for cell division. Blocking these proteins helps to slow down cells that are dividing, which slows down cancer growth.

What is palbociclib used for?

Palbociclib is used to treat adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer. It should always be used in combination with another medicine either:

Important information

Palbociclib may cause serious side effects, including:

Low white blood cell counts (neutropenia). This increases your risk of serious infections. Low white blood cell counts are very common when taking palbociclib and may cause serious infections that can lead to death. Your healthcare provider should check your white blood cell counts before and during treatment.

If you develop low white blood cell counts during treatment, your healthcare provider may stop your treatment, decrease your dose, or may tell you to wait to begin your treatment cycle. Tell your healthcare provider right away if you have signs and symptoms of low white blood cell counts or infections such as fever and chills.

Lung problems (pneumonitis). Palbociclib may cause severe or life-threatening inflammation of the lungs during treatment that can lead to death. Tell your healthcare provider right away if you have any new or worsening symptoms, including:

Other possible side effects are listed further down the page. 

What should I tell my doctor before taking palbociclib?

Before you take palbociclib, tell your healthcare provider if you:

How should I take palbociclib?

Dosing information

The usual dose of palbociclib is a 125 mg tablet or capsule swallowed once a day for 21 days in a row. You then have 7 days in a row of not taking Palbociclib tablets or capsules. This makes up a complete cycle of 28 days.

Your dosage may be changed by your health professional if you are having side effects, changes in your blood tests, liver problems or if you are taking certain medications that interact with palbociclib.

What are the side effects of palbociclib?

Palbociclib may cause serious side effects. Also see “Important information’ on this page.

Common side effects of palbociclib when used with either letrozole or fulvestrant include:

Palbociclib may cause fertility problems in males. This may affect your ability to father a child. Talk to your healthcare provider about family planning options before starting palbociclib if this is a concern for you.

Tell your healthcare provider if you have any side effect that bothers you or that does not go away.

These are not all of the possible side effects of this medicine.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Some medications interact with palbociclib, so it is important to tell your doctor about any medicines that you are currently taking, or if you start or stop any medicine while you are having cancer treatment. Also tell your doctor about any over-the-counter medicines, vitamins, minerals or herbal products that you take.

To find out more about interactions with palbociclib click the link below:

Pregnancy and breastfeeding

You should not take palbociclib if you are pregnant or planning a pregnancy, as it can harm your unborn baby.

If you are breastfeeding or planning to breastfeed. It is not known if palbociclib passes into your breast milk. Do not breastfeed during treatment with palbociclib and for 3 weeks after the last dose.


Keep palbociclib and all medicines out of the reach of children.

What are the ingredients in palbociclib?

Active ingredient: palbociclib

Inactive ingredients:

Ibrance Capsule: microcrystalline cellulose, lactose monohydrate, sodium starch glycolate, colloidal silicon dioxide, magnesium stearate, and hard gelatin capsule shells.The light orange, light orange/caramel and caramel opaque capsule shells contain: gelatin, red iron oxide, yellow iron oxide, and titanium dioxide.

Ibrance tablet: microcrystalline cellulose, colloidal silicon dioxide, crospovidone, magnesium stearate, succinic acid, HPMC 2910/hypromellose, titanium dioxide, triacetin, and FD C Blue #2/Indigo Carmine Aluminum Lake. In addition, the 75 mg and 125 mg tablets contain red iron oxide and the 100 mg tablets contain yellow iron oxide.

Popular FAQ

Ibrance (palbociclib) is an expensive medicine used to treat breast cancer, but most people do not pay the full price for this drug. Your insurance, the manufacturer of Ibrance, or patient assistance programs may be available to help you pay for this medication. Continue reading

Head-to-head trials comparing Verzenio to Ibrance have not been conducted. However, one is currently underway with results expected in 2023. Verzenio is taken twice daily, every day. Ibrance is taken every day for 21 days followed by a 7-day break. Verzenio can be used as monotherapy or in combination with other treatments. Ibrance is always taken in combination with either an aromatase inhibitor or fulvestrant. Verzenio is more likely than Ibrance to cause severe diarrhea. Both Verzenio and Ibrance can be used as combination treatment to treat breast cancer in men. Verzenio is also approved to treat adults with early breast cancer at high risk of recurrence in combination with endocrine treatment (tamoxifen or an aromatase inhibitor). Continue reading

Both Verzenio and Ibrance belong to the same class of medicine, called CDK 4/6 inhibitors, therefore, because they are both in the same class of medicines, clinically, it is unknown if there is an advantage in switching from one to another if one fails. However, research has shown breast cancer cells can acquire resistance to CDK 4/6 inhibitors by producing higher amounts of CDK6. Laboratory trials have shown that a “treatment holiday” of 28 days reversed this resistance, which implies that there may be some benefit of either stopping Ibrance temporarily or switching from Ibrance to Verzenio after a treatment break. Comparative trials comparing Verzenio to Ibrance are currently underway with results expected in 2023. Continue reading

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Further information

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