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:

• an aromatase inhibitor as initial endocrine-based therapy in postmenopausal women or in men; or
• fulvestrant in patients with disease progression following endocrine therapy.

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:

• trouble breathing or shortness of breath
• cough with or without mucus
• chest pain

Other possible side effects are listed further down the page. 

• Take palbociclib tablets and capsules exactly as your healthcare provider tells you.
• Try to take it at the same time each day.
• You should take palbociclib capsules with food.
• You can take palbociclib tablets with or without food
• Swallow capsules and tablets whole. 
• Palbociclib tablets should not be chewed, crushed, or split before swallowing. Palbociclib capsules should not be chewed, crushed. You should not open capsules before swallowing.
• Do not take tablets or capsules if they are broken, cracked, or otherwise not whole.
• You should not have grapefruit and grapefruit products during treatment with this medicine. Grapefruit can increase the amount of it in your blood.
• You should not change your dose or stop taking this medicine unless your healthcare provider tells you.
• If you miss a dose of palbociclib or vomit after taking a dose,  you should not take another dose on that day. Take your next dose at your regular time.
• If you take too much of this medicine, call your healthcare provider right away or go to the nearest hospital emergency room.

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.

• Take the recommended dose of an aromatase inhibitor when given with Palbociclib. Please refer to the Full Prescribing Information for the aromatase inhibitor being used.
• Take the recommended dose of fulvestrant on Days 1,15, 29, and once monthly  thereafter. Please refer to the Full Prescribing Information of fulvestrant.

• If you are a pre/perimenopausal woman being treated with the combination palbociclib plus fulvestrant therapy you should also be treated with luteinizing hormone-releasing hormone (LHRH) agonists according to current clinical practice standards.
• If you are a man being treated with combination palbociclib plus aromatase inhibitor therapy, consider treatment with an LHRH agonist according to current clinical practice standards. 

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.

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

• have fever, chills, or any other signs or symptoms of infection.
• have liver or kidney problems.
• have any other medical conditions.
• are pregnant, or plan to become pregnant. See below for more information on palbociclib and pregnancy, as it can harm your unborn baby.
• are breastfeeding or plan to breastfeed. Do not breastfeed during treatment with palbociclib and for 3 weeks after the last dose.  See below for more information on palbociclib and breastfeeding.

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 excess heat and moisture (not in the bathroom).

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 (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

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. http://www.upandaway.org

Do not eat grapefruit or drink grapefruit juice while taking this medication.

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:

• Low red blood cell counts and low platelet counts are common with this medicine. Call your healthcare provider right away if you develop any of these symptoms during treatment:
  • dizziness
  • bleeding or bruising more easily
  • shortness of breath
  • weakness
  • nosebleeds
• infections (see ‘Important information’ above on this page)
• tiredness
• diarrhea
• hair thinning or hair loss
• vomiting
• nausea
• sore mouth
• abnormalities in liver blood tests
• rash
• loss of appetite

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:

Keep all appointments with your doctor and the laboratory. Your doctor may order certain lab tests before and during your treatment to check your body's response to palbociclib.

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.