Palbociclib

Palbociclib is a prescription medication used to treat advanced (metastatic) breast cancer. 

It is given with another medication to treat hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer.

Palbociclib belongs to a group of drugs called CDK 4/6 inhibitors. These work by inhibiting CDK 4/6 molecules that are involved in promoting the growth of cancer cells.

Palbociclib comes in a capsule form and is taken once a day with food.

Common side effects of palbociclib include decreased white blood cell count, fatigue, and low red blood cell count (anemia).

Palbociclib is a prescription medication used to treat HR-positive, HER2-negative advanced breast cancer with:

• with letrozole for postmenopausal women who have not received endocrine-based therapy
• with fulvestrant in women with disease progression following endocrine therapy

Palbociclib may be found in some form under the following brand names:

• Ibrance

Serious side effects have been reported with palbociclib. See the “Palbociclib Drug Precautions” section.

Common side effects of palbociclib include the following:

• decreased white blood cell count
• fatigue
• low red blood cell count (anemia)
• nausea and vomiting
• inflammation or irritation of the mouth and lips, such as canker sores (stomatitis)
• upper respiratory tract infections
• hair loss
• decreased appetite
• nosebleeds

This is not a complete list of side effects. Ask your doctor or pharmacist for more information. Tell your doctor if you have any side effect that bothers you or that does not go away. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Tell your doctor about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. Especially tell your doctor if you take:

• medications that block a protein in the body (CYP3A4) such as some macrolide antibiotics (clarithromycin, telithromycin), some HIV protease inhibitors (indinavir, nelfinavir, ritonavir, saquinavir), some HCV protease inhibitors (boceprevir, telaprevir), some azole antifungals (ketoconazole, itraconazole, posaconazole, voriconazole), conivaptan (Vaprisol), delavirdine (Rescriptor), and nefazodone
• medications that increase the activity of the enzyme CYP3A4 such as carbamazepine (Tegretol, Equetro, Carbatrol), phenobarbital, phenytoin (Dilantin), rifampin (Rifadin), St John's wort, and nimodipine (Nimotop)
• medications that use the enzyme CYP3A4 such as budesonide (Entocort), cyclosporine (Neoral, Gengraf, Sandimmune), darifenacin (Enablex), dihydroergotamine (Migranal), fentanyl (Abstral, Fentora, Onsolis, Actiq), pimozide (Orap), quinidine (Cardioquin, Duraquin, Quinact), sirolimus (Rapamune), tacrolimus (Prograf), terfenadine (Seldane), fluticasone (Flovent HFA, Flonase), eletriptan (Relpax), lovastatin (Mevacor), quetiapine (Seroquel), sildenafil (Viagra, Revatio), and simvastatin (Zocor)

This is not a complete list of drug interactions. Ask your doctor or pharmacist for more information.

Serious side effects have been reported with palbociclib including the following:

Low white blood cell count (neutropenia) and infections. White blood cells are responsible for fighting off infections in the body. Tell your healthcare provider right away if you have some or all of the following symptoms of a low white blood cell count or infection:

• getting frequent infections
• chills or sweating
• having a fever of 100.5 °F or higher
• sore throat, or having sores in the mouth
• ulcers or sores
• stomach pain

Palbociclib can harm your unborn baby.

• Females who are able to become pregnant and who take palbociclib should use effective birth control during treatment and for at least 3 weeks after stopping this medication. 
• Males who are taking palbociclib, with female partners who can become pregnant should use effective birth control during treatment with Ibrance for 3 months after the final dose of palbociclib.

Do not take palbociclib if you are allergic to palbociclib or to any of its ingredients.

Grapefruit and grapefruit juice may interact with palbociclib and lead to potentially dangerous effects. Discuss the use of grapefruit products with your doctor.

Before taking palbociclib, tell your doctor about all of your medical conditions. Especially tell your doctor if you:

• are allergic to palbociclib or to any of its ingredients
• have liver or kidney problems
• have fever, chills, or any other signs or symptoms of infection
• have or have had problems with fertility (for males)
• are pregnant or plan to become pregnant
• are breastfeeding or plan to breastfeed

Tell your doctor about all the medicines you take including prescription and non-prescription medicines, vitamins, and herbal supplements.

Tell your doctor if you are pregnant or plan to become pregnant.

In animal studies, pregnant animals were given this medication and had some babies born with problems. No well-controlled studies have been done in humans. 

Palbociclib can harm your unborn baby.

• Females who are able to become pregnant and who take palbociclib should use effective birth control during treatment and for at least 3 weeks after stopping this medication. 
• Males who are taking palbociclib, with female partners who can become pregnant should use effective birth control during treatment with Ibrance for 3 months after the final dose of palbociclib.
• Talk to your healthcare provider about birth control methods that may be right for you during this time.
• If you become pregnant or think you are pregnant, tell your healthcare provider right away.

Tell your doctor if you are breastfeeding or plan to breastfeed.

It is not known if palbociclib crosses into human milk. Because many medications can cross into human milk and because of the possibility for serious adverse reactions in nursing infants with use of this medication, it is advised for a woman to stop breastfeeding a child while taking this medication.

Take palbociclib as prescribed.

Palbociclib comes in a capsule form and is taken once a day, with food.

• Swallow capsules whole. Do not chew, crush or open capsules before swallowing them.
• Do not take any capsules that are broken, cracked, or that look damaged.
• Avoid grapefruit and grapefruit products during treatment with palbociclib. Grapefruit may increase the amount of palbociclib in your blood.
• Do not change your dose or stop taking palbociclib unless your healthcare provider tells you.

If you miss a dose of palbociclib or vomit after taking a dose of Ibrance, do not take another dose on that day. Take your next dose at your regular time.

Take this medication exactly as prescribed by your doctor. Follow the directions on your prescription label carefully.

• The dose your doctor recommends may be based on the following:
• the condition being treated
• other medical conditions you have
• other medications you are taking
• how you respond to this medication
• your weight
• your height
• your age
• your gender

The recommended dose of Ibrance (palbociclib) for the treatment of advanced (metastatic) breast cancer is 125 mg once daily for 21 days, followed by 7 days of being off of the medication. This medication should be used in combination with letrozole. Changes in dose or schedule may be required depending on how well the medication is tolerated. 

If you take too much palbociclib, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

If palbociclib is administered by a healthcare provider in a medical setting, it is unlikely that an overdose will occur. However, if overdose is suspected, seek emergency medical attention.

• Store palbociclib at room temperature
• Keep this and all medicines out of the reach of children