Palbociclib belongs to a group of cancer-fighting medications called protein kinase inhibitors. It works by recognizing certain types of cancer cells and blocking the action of chemicals that cause them to divide and grow. This may slow down or stop cancers from growing and dividing.

This medication is used in combination with other medication, to treat advanced breast cancer, and to treat breast cancer that has spread to other parts of the body (metastasized).

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended dose of palbociclib is 125 mg taken by mouth, once a day for 21 days, followed by 7 days without taking the medication. This forms a 28-day cycle, which is repeated as long as you are benefiting from the medication. Depending on the side effects you experience and how well you tolerate this medication, your doctor may reduce the dose.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

There are two forms of palbociclib: capsules and tablets. Palbociclib capsules should be taken with food. Palbociclib tablets may be taken with or without food. Try to take this medication the same way and at the same time each day, to make sure a constant amount of medication stays in your body.

Swallow this medication whole with some fluid. Do not crush, chew, or open the capsules or tablets before swallowing them. If you find a broken, cracked, or open capsule or tablet, discard it safely. Do not take any capsule or tablet that is not intact.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. If you vomit after taking your dose for the day, do not take another dose. Continue taking the medication the next day. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, in its original container, protect it from light and moisture, and keep it out of the reach of children.

Capsules

75 mg
Each opaque, hard gelatin, size 2 capsule with light orange cap and body, printed with white ink "Pfizer" on the cap, "PBC 75" on the body, contains 75 mg of palbociclib. Nonmedicinal ingredients: microcrystalline cellulose, lactose monohydrate, sodium starch glycolate, colloidal silicon dioxide, and magnesium stearate; capsule shell: gelatin, red iron oxide, yellow iron oxide, and titanium dioxide; printing ink: shellac, titanium dioxide, ammonium hydroxide, propylene glycol, and simethicone.

100 mg
Each opaque, hard gelatin, size 1 capsule with caramel cap and light orange body, printed with white ink "Pfizer" on the cap, "PBC 100" on the body, contains 100 mg of palbociclib. Nonmedicinal ingredients: microcrystalline cellulose, lactose monohydrate, sodium starch glycolate, colloidal silicon dioxide, and magnesium stearate; capsule shell: gelatin, red iron oxide, yellow iron oxide, and titanium dioxide; printing ink: shellac, titanium dioxide, ammonium hydroxide, propylene glycol, and simethicone.

125 mg
Each opaque, hard gelatin, size 0 capsule with caramel cap and body, printed with white ink "Pfizer" on the cap, "PBC 125" on the body, contains 125 mg of palbociclib. Nonmedicinal ingredients: microcrystalline cellulose, lactose monohydrate, sodium starch glycolate, colloidal silicon dioxide, magnesium stearate, and hard gelatin capsule shells; capsule shell: gelatin, red iron oxide, yellow iron oxide, and titanium dioxide; printing ink: shellac, titanium dioxide, ammonium hydroxide, propylene glycol, and simethicone.

Tablets

75 mg
Each round, light purple, film-coated tablet, debossed with "Pfizer" on one side and "PBC 75" on the other side, contains 75 mg of palbociclib. Nonmedicinal ingredients: colloidal silicon dioxide, crospovidone, FD&C Blue No. 2 aluminum lake, hypromellose, magnesium stearate, microcrystalline cellulose, red iron oxide succinic acid, titanium dioxide, and triacetin.

100 mg
Each oval, green, film-coated tablet, debossed with "Pfizer" on one side and "PBC 100" on the other side, contains 100 mg of palbociclib. Nonmedicinal ingredients: colloidal silicon dioxide, crospovidone, FD&C Blue No. 2 aluminum lake, hypromellose, magnesium stearate, microcrystalline cellulose, succinic acid, titanium dioxide, triacetin, and yellow iron oxide.

125 mg
Each oval, light purple, film-coated tablet, debossed with "Pfizer" on one side and "PBC 125" on the other side, contains 125 mg of palbociclib. Nonmedicinal ingredients: colloidal silicon dioxide, crospovidone, FD&C Blue No. 2 aluminum lake, hypromellose, magnesium stearate, microcrystalline cellulose, red iron oxide, succinic acid, titanium dioxide, and triacetin.

Do not take this medication if you are allergic to palbociclib or any ingredients of the medication.

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• constipation
• cough
• diarrhea
• hair thinning or loss
• headache
• loss of appetite
• mouth sores
• nausea
• rash
• tiredness
• vomiting
• weakness

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:

• fever
• tingling in the arms or legs
• shortness of breath
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath)
• signs of a blood clot in the arm or leg (tenderness, pain, swelling, warmth, or redness in the arm or leg)
• signs of a blood clot in the lungs (difficulty breathing, sharp chest pain that is worse when breathing in, coughing, coughing up blood, sweating, or passing out)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of infection (symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
• symptoms of hand-foot syndrome (e.g., red or swollen palms, thick calluses and blisters on the hands and soles of feet, tingling or burning, tightness of the skin)
• symptoms of lung inflammation (e.g., cough, shortness of breath, trouble breathing)
• tingling or abnormal feeling (especially in the arms and legs)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• symptoms of an allergic reaction (e.g., difficulty breathing, hives, itchy skin rash, or swelling of the mouth or throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Anemia: Palbociclib may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired or pale skin, contact your doctor as soon as possible.

Your doctor will do blood tests regularly to monitor the number of specific types of blood cells, including red blood cells, in your blood.

Blood clots: This medication may increase the chance of blood clot formation, causing reduction of blood flow to organs or the extremities.

If you have a history of clotting you may be at increased risk of experiencing blood clot-related problems such as heart attack, stroke, or clots in the deep veins of your leg. Discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms such as sharp pain and swelling in the leg, difficulty breathing, chest pain, blurred vision, or difficulty speaking, contact your doctor immediately.

Drowsiness/dizziness: Palbociclib may cause drowsiness or dizziness, affecting your ability to drive or operate machinery. Avoid driving, operating machinery, or performing other potentially hazardous tasks until you have determined how this medication affects you.

Fruit/fruit juice: Certain fruits or their juices may change the amount of palbociclib in your body. Do not consume grapefruit, grapefruit juice, starfruit, pomegranate, or Seville oranges while taking this medication.

Infection: As well as killing cancer cells, palbociclib can reduce the number of cells that fight infection in the body (white blood cells). If possible, avoid contact with people with contagious infections. Tell your doctor immediately if you notice signs of an infection, such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness. Your doctor will do blood tests regularly to monitor the number of specific types of blood cells in your blood.

Liver function: Decreased liver function or liver disease may cause this medication to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking this medication.

Lung inflammation: Rarely, some people taking this medication have experienced lung inflammation (interstitial lung disease), causing difficulty breathing. This problem can be severe and life-threatening. If you experience new or worsening shortness of breath or cough (with or without fever) at any time while you are taking palbociclib, contact your doctor immediately.

Male fertility: This medication may impair male fertility. You should consider sperm preservation prior to starting treatment with palbociclib. People whose partners could become pregnant should use effective birth control during treatment and for at least 97 days after the last dose of palbociclib.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately. If you are able to become pregnant, you should use effective birth control while you are taking this medication and for at least 21 days after stopping the medication. People taking this medication whose partners could become pregnant should use effective birth control during treatment and for at least 97 days after the last dose of palbociclib.

Breast-feeding: It is not known if palbociclib passes into breast milk. If you are breast-feeding and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

For a full list of interactions, use the Drug Interaction Checker available on the Drugs.com website.

If you are taking other medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.