Kisqali Femara Co-Pack (Ribociclib and Letrozole) Oral: Uses, Side Effects, Dosages

What Is Kisqali Femara Co-Pack?

The Kisqali Femara Co-Pack is a prescription that contains two medications, ribociclib (Kisqali) and letrozole (Femara), used as a first-line treatment for adults who have advanced or metastatic hormone-receptor-positive human epidermal growth factor-2 receptors (HER2)-negative breast cancer. Metastatic cancer is cancer that has spread from the primary site to other areas of the body.

This type of cancer contains estrogen or progesterone receptors, which help cancer cells grow. However, unlike HER2-positive cancers, HER2-negative cancers do not have abnormally high levels of HER2 receptors. HER2 proteins are found on breast cells and facilitate cancer growth.

Neither of the medications in this treatment is chemotherapy. Kisqali is a medication in the class of CDK4/6 inhibitors. It works by targeting the CDK4/6 protein, which is a protein that allows cell growth. Blocking this protein from working can stop the growth of cancer cells.

Femara is a medication in the class of aromatase inhibitors (AIs). An AI works by stopping an enzyme called aromatase from being able to turn hormones into estrogen. In hormone receptor-positive breast cancer, cancer cells use estrogen to grow. Blocking the amount of estrogen produced in the body can prevent cancer cell growth.

Each medication comes in tablet form to be taken orally.

Drug Facts

Generic Name: Ribociclib and letrozole

Brand Name(s): Kisqali Femara Co-Pack

Drug Availability: Prescription

Administration Route: Oral

Therapeutic Classification: CDK4/6 inhibitor and aromatase inhibitor

Available Generically: No

Controlled Substance: N/A

Active Ingredient: Ribociclib and letrozole

Dosage Form(s): Tablet

What Is Kisqali Femara Co-Pack Used For?

The Kisqali Femara Co-Pack is used for the initial endocrine treatment of breast cancer that has spread locally or distantly in the body. Breast cancer must be hormone receptor-positive and HER2-negative.

How to Take Kisqali Femara Co-Pack

Each medication comes packaged separately. The doses for Kisqali and Femara are different. Kisqali is usually taken once daily for three weeks, followed by one week off, while Femara is taken every day.

Take the medications by swallowing the tablets whole once daily and at around the same time each day. Do not chew, crush, or break the tablets. The Kisqali Femara Co-Pack can be taken with or without food.


The Kisqali Femara Co-Pack comes in a package containing Kisqali and Femara in different packaging. The medications should be stored at room temperature and kept only in the original packaging.

How Long Does Kisqali Femara Co-Pack Take to Work?

It can take a few weeks of routine use for the medication to reach a steady state in the body. The ordering cancer physician may order scans after a few months of therapy to see how cancer is responding to the treatment.

What Are the Side Effects of Kisqali Femara Co-Pack?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the FDA at or 1-800-FDA-1088.

Common Side Effects

The most common side effects that were experienced in those taking the Kisqali Femara Co-Pack include:

  • Low white blood cell levels
  • Low red blood cell levels
  • Headaches
  • Nausea and vomiting
  • Diarrhea
  • Increased risk of infection
  • Constipation
  • Hair loss
  • Pain in the back
  • Feeling tired
  • Skin rash

Severe Side Effects

Some severe side effects can be experienced when taking Kisqali Femara Co-Pack. If you’re experiencing a medical emergency, call 911 or go to your nearest emergency room. Serious side effects and their symptoms can include the following:

  • Lung problems. Lung inflammation may occur, which could be severe or life-threatening. Symptoms can include cough, chest pain, or difficulty breathing. 
  • Heart rhythm problems. A heart rhythm issue called QT prolongation can occur and may lead to more severe heart rhythm problems. Symptoms can include a fast heart rate or dizziness. 
  • Liver problems. It is possible that liver dysfunction can occur on this medication. Symptoms can include abdominal pain and yellowing of the skin or eyes.
  • Skin problems. A severe skin reaction can occur, which would cause the skin to become red, inflamed, or blistered.

Long-Term Side Effects

The Kisqali Femara Co-Pack can potentially lead to infertility in males and impair fertility in females.

Report Side Effects

Kisqali Femara Co-Pack may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA’s MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Kisqali Femara Co-Pack Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor’s orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage form (tablets):

    • For metastatic breast cancer:

      • Adults—

        • Ribociclib: 600 milligrams (mg) (three 200 mg tablets) taken as a single dose, once a day for 21 days in a row, followed by 7 days without medicine. Your doctor may adjust your dose as needed and tolerated.
        • Letrozole: 2.5 milligrams (mg) once a day for 28 days.
      • Children—Use and dose must be determined by your doctor.


Dose modifications may be needed if any severe side effects occur. The dose modifications are typically required for Kisqali and not Femara. If needed, your oncologist will determine how much to change your dose.

Missed Dose

A missed dose should be skipped and taken the next day as scheduled. Never double up on either of the medications.

Overdose: What Happens If I Take Too Much Kisqali Femara Co-Pack?

If you take too much of the Kisqali Femara Co-Pack, contact your cancer care team immediately or go to the nearest emergency room.

What Happens If I Overdose on Kisqali Femara Co-Pack

If you think you or someone else may have overdosed on Kisqali Femara Co-Pack, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn’t breathing after taking Kisqali Femara Co-Pack, call 911 immediately.


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IBM Micromedex®

It is very important that your doctor check your progress at regular visits to make sure this medicine is working properly. Blood tests may be needed to check for unwanted effects.

It is unlikely that a postmenopausal woman may become pregnant. But, using this medicine while you are pregnant can harm your unborn baby. If you are a woman who can bear children, your doctor may give you a pregnancy test before you start using this medicine to make sure you are not pregnant. Use an effective form of birth control to keep from getting pregnant during treatment and for at least 3 weeks after your last dose. If you think you have become pregnant while using the medicine, tell your doctor right away.

If you plan to have children, talk with your doctor before using this medicine. Some men and women using this medicine have become infertile (unable to have children).

Interstitial lung disease or pneumonitis can occur while using this medicine. This can be life-threatening and requires immediate medical attention. Check with your doctor right away if you have chest pain, cough, difficulty with breathing, fever or chills.

Serious skin reactions, including Stevens-Johnson Syndrome, toxic epidermal necrolysis, or drug reaction with eosinophilia and systemic symptoms (DRESS) can occur with this medicine. Check with your doctor right away if you have black, tarry stools, blistering, peeling, or loosening of the skin, chest pain, chills, cough, fever, painful or difficult urination, red skin lesions, sore throat, sores, ulcers, or white spots on the lips or in the mouth, swollen glands, unusual bleeding or bruising, or unusual tiredness or weakness with this medicine.

Contact your doctor right away if you have any changes to your heart rhythm. You might feel dizzy or faint, or you might have a fast, pounding, or uneven heartbeat. Make sure your doctor knows if you or anyone in your family has ever had a heart rhythm problem including QT prolongation.

Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.

Ribociclib and letrozole combination can temporarily lower the number of some types of blood cells in your blood. Because of this, you may bleed or get infections more easily. To help with these problems, avoid being near people who are sick or have infections. Wash your hands often. Stay away from rough sports or other situations where you could be bruised, cut, or injured. Brush and floss your teeth gently. Be careful when using sharp objects, including razors and fingernail clippers.

Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal (eg, St. John’s wort) or vitamin supplements.

What Are Reasons I Shouldn’t Take Kisqali Femara Co-Pack?

People who are allergic to Kisqali, Femara, or any of the ingredients in those medications should not take it. You should also not take the Kisqali Femara Co-Pack if you are pregnant or breastfeeding.

What Other Medications Interact With Kisqali Femara Co-Pack?

Certain medications can interact with how Kisqali Femara Co-Pack is absorbed by the body, leading to either too much or not enough of the medication being absorbed.

Avoid the following while taking Kisqali Femara Co-Pack:

  • Grapefruit and grapefruit juice
  • Biaxin, Biaxin XL (clarithromycin)
  • Itraconazole
  • Ketoconazole
  • Dilantin (phenytoin)
  • Rifampin
  • St. John’s Wort
  • Tegretol, Carbatrol, Epitol, Equetro, Tegretol XR, Teril (carbamazepine)
  • Pacerone (amiodarone)
  • Betapace, Betapace AF, Sorine, Sotylize (sotalol)
  • Haldol (haloperidol)
  • Dolophine, Methadone HCl Intensol, Methadose (methadone)
  • Zofran (ondansetron)

What Medications Are Similar?

In addition to Kisqali, two other CDK4/6 inhibitors are used to treat breast cancer: Verzenio (abemaciclib) and Ibrance (palbociclib).

In the class of aromatase inhibitors, other medications besides Femara include Arimidex (anastrozole) and Aromasin (exemestane). These all work similarly in blocking androgen hormones from becoming estrogen.

These medications are not used in combination with the Kisqali Femara Co-Pack.

Frequently Asked Questions

  • What is the Kisqali Femara Co-Pack used for?

    The Kisqali Femara Co-Pack is used to treat a type of breast cancer that has spread to other areas of the body and that is hormone receptor-positive and HER2 negative.

  • How does Kisqali Femara Co-Pack work?

    Kisqali works by blocking the CDK4/6 pathway that breast cancer cells use to grow. When these pathways are blocked, the cells cannot reproduce. In breast cancer which is hormone receptor-positive, estrogen helps cancer to develop. Femara blocks other hormones from being turned into estrogen, decreasing the fuel feeding the cancer.

  • What drugs should not be taken with Kisqali Femara Co-Pack?

    There are several medications that you should not take with Kisqali Femara Co-Pack. Some of these include:

    • Ketoconazole
    • Amiodarone
    • Clarithromycin
    • St. John’s Wort

    You should also avoid consuming grapefruit or grapefruit juice while on this medication.

  • What are the side effects of Kisqali Femara Co-Pack?

    Some of the side effects of the Kisqali Femara Co-Pack include:

    • Nausea and vomiting
    • Headache
    • Low white blood cell and red blood cell counts
    • Diarrhea
    • Constipation
    • Increased risk of infection

How Can I Stay Healthy While Taking Kisqali Femara Co-Pack?

The Kisqali Femara Co-Pack can be an effective treatment in the fight against breast cancer. This Co-Pack can make it easier to keep track of the medications, but it is important to keep the medicines separate and organized as they require different doses. Talk to your healthcare team if you’re concerned about any side effects you’re experiencing.

Medical Disclaimer

Verywell Health’s drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.