What is Tybost (cobicistat), and how does it work?

Tybost is a prescription medicine used in adults and children:

  • 1 time each day with the Human Immunodeficiency Virus-1 (HIV-1) medicines atazanavir or darunavir, to increase the amount of those medicines in your blood.
    • When taken with atazanavir, Tybost is used in adults, and in children who weigh at least 77 pounds (35 kg).
    • When taken with darunavir, Tybost is used in adults, and in children who weigh at least 88 pounds (40 kg).
  • Tybost is not an antiretroviral medicine and does not treat the HIV-1 virus. You must also take all the antiretroviral HIV-1 medicines prescribed by your healthcare provider even if you take Tybost and atazanavir or darunavir.
  • Tybost should not be used if you take darunavir when prescribed by your healthcare provider to be taken 2 times each day, or if you take other HIV-1 protease inhibitor medicines, including fosamprenavir, saquinavir, or tipranavir.

It is not known if Tybost when taken with atazanavir is safe and effective in children who weigh less than 77 pounds (35 kg).

It is not known if Tybost when taken with darunavir is safe and effective in children who weigh less than 88 pounds (40 kg).

What are the side effects of Tybost?

Tybost when taken with certain other medicines can cause new or worse kidney problems, including kidney failure. Your healthcare provider should check your kidneys before you start and while you are taking Tybost.

The most common side effects of Tybost with atazanavir include yellowing of the skin and rash.

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

These are not all the possible side effects of Tybost. For more information, ask your healthcare provider or pharmacist.

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

What is the dosage for Tybost?

  • Take Tybost exactly as your healthcare provider tells you.
  • Do not change your dose or stop taking Tybost without first talking with your healthcare provider.
  • Stay under the care of your healthcare provider during treatment with Tybost. See your healthcare provider regularly while taking Tybost.
  • Take Tybost 1 time each day at the same time you take atazanavir or darunavir. It is important to take these medicines on a regular dosing schedule.
  • Take Tybost with atazanavir or Tybost with darunavir, along with food.
  • If you take too much Tybost, call your healthcare provider or go to the nearest hospital emergency room right away.
  • Do not run out of Tybost. The virus in your blood may become resistant to the HIV-1 medicine atazanavir or darunavir if Tybost is stopped for even a short time. When your supply starts to run low, get more from your healthcare provider or pharmacy.

What drugs interact with Tybost?

Do not take Tybost combined with atazanavir or darunavir if you also take a medicine that contains:

Do not take Tybost with atazanavir if you also take a medicine that contains:

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Is Tybost safe to take while pregnant or breastfeeding?

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

  • are pregnant or plan to become pregnant
    • It is not known if Tybost can harm your unborn baby.
    • Tybost should not be used during pregnancy because you may not have enough Tybost in your body during pregnancy.
    • Tell your healthcare provider if you become pregnant while taking Tybost. Your healthcare provider may prescribe different medicines if you become pregnant while taking Tybost.
    • Pregnancy Registry: There is a pregnancy registry for women who take Tybost during pregnancy. The purpose of the registry is to collect information about the health of you and your baby. Talk to your healthcare provider about how you can take part in this registry.
  • are breastfeeding or plan to breastfeed. Do not breastfeed if you take Tybost.
    • You should not breastfeed if you have HIV-1 because of the risk of passing HIV-1 to your baby.
    • It is not known if Tybost can pass to your baby in your breast milk.

Talk to your healthcare provider about the best way to feed your baby.

Summary

Tybost (cobicistat) is a prescription medicine used in adults and children with the Human Immunodeficiency Virus-1 (HIV-1) medicines atazanavir or darunavir, to increase the amount of those medicines in your blood.

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Medically Reviewed on 10/23/2020
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All sections courtesy of the U.S. Food and Drug Administration