Tybost (Cobicistat) - Oral

What Is Tybost?

Tybost is a prescription medication that is used to boost the effects of Reyataz (atazanavir) or Prezista (darunavir) once-daily dosing regimen in combination with other antiretroviral drugs in the treatment of HIV-1 infection in adults or children weighing at least 77 pounds (35 kilograms) (with atazanavir) or at least 88 pounds (40 kilograms) (with darunavir).

Tybost is a strong CYP3A4 inhibitor, and it helps increase the levels of specific HIV protease inhibitors (atazanavir and darunavir) in the body by competing with their metabolism through the liver.

Drug Facts

Generic Name: Cobicistat

Brand Name(s): Tybost

Drug Availability: Prescription

Therapeutic Classification: CYP3A4 inhibitor

Available Generically: No

Controlled Substance: N/A

Administration Route: Oral

Active Ingredient: Cobicistat

Dosage Form(s): Oral tablet

What Is Tybost Used For?

Tybost is used with other antiretrovirals to treat HIV-1 infection in adults or children.

Since the epidemic started, around 84.2 million people have been infected with HIV, and approximately 40.1 million people have died of HIV. By the end of 2021, 38.4 million people worldwide were living with HIV. Africa is the most severely affected part of the world. Nearly one in 25 adults in Africa lives with HIV. This accounts for over two-thirds of the population that lives with HIV globally.

How to Take Tybost

Take Tybost by mouth as prescribed by your healthcare provider, along with food. Do not use more than directed. It would help if you took Tybost at the same time as atazanavir or darunavir. It is essential to take these medicines on a regular dosing schedule. Here are a few things to keep in mind:

  • Tybost is not an antiretroviral medicine and does not treat/cure the HIV-1 virus. It would help if you took all the antiretroviral HIV-1 medications prescribed as part of your combination treatment.
  • Do not change your dose or stop taking Tybost without first talking with your healthcare provider. If you stop the medicine for a short time, your HIV-1 infection may become harder to treat.
  • Contact your healthcare provider or pharmacist when your supply is running low, so you do not run out.
  • Tybost should not be used if your healthcare provider has prescribed you to take darunavir twice daily or other HIV-1 protease inhibitor medicines such as Lexiva, Telzir (fosamprenavir), Invirase (saquinavir), or Aptivus (tipranavir).

Storage

Store Tybost at room temperature, away from heat, moisture, and direct light, in its original child-resistant container. Keep the container tightly closed. Do not use Tybost if the seal over the bottle opening is broken or missing.

Off-Label Uses

The off-label uses of Tybost are lacking.

How Long Does Tybost Take to Work?

It takes Tybost 3.5 hours to reach peak drug concentrations (Tmax) after taking it by mouth. The time it takes Tybost to work may be different for everyone. Be sure to check with your healthcare provider or pharmacist for any questions.

What Are the Side Effects of Tybost?

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 pharmacist or a healthcare provider. You may report side effects to the Food and Drug Administration (FDA) at fda.gov/medwatch or 800-FDA-1088.

Common Side Effects

Common side effects include:

Severe Side Effects

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you have a medical emergency. Serious side effects and their symptoms can include the following:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness or trouble breathing
  • Rash
  • Rhabdomyolysis
  • Acquired Fanconi syndrome (kidney disorder), acute renal failure, or kidney disease (change in how much or how often you urinate, blood in your urine, lower back or side pain)

Long-Term Side Effects

Long-term effects of Tybost are lacking.

Report Side Effects

Tybost 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 provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Tybost Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

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 enhancement of atazanavir:
      • Adults and children weighing 35 kilograms (kg) or more—150 milligrams (mg) once a day, taken with atazanavir 300 mg once a day.
      • Children weighing less than 35 kg—Use and dose must be determined by your doctor.
    • For enhancement of darunavir:
      • Adults and children weighing 40 kilograms (kg) or more—150 milligrams (mg) once a day, taken with darunavir 800 mg once a day.
      • Children weighing less than 40 kg—Use and dose must be determined by your doctor.

Modifications

The following modifications (changes) should be kept in mind when using Tybost:

  • Pregnancy: The use of Tybost is not recommended during pregnancy. It is not known if Tybost can harm your unborn baby. If you're pregnant or planning to become pregnant, please talk with your healthcare provider. There is a pregnancy exposure registry that monitors fetal outcomes in women exposed to Tybost during pregnancy. Healthcare providers are encouraged to register patients by calling the Antiretroviral Pregnancy Registry at 1-800-258-4263.
  • Breastfeeding: It is recommended that you do not breastfeed to avoid spreading HIV to your baby through your breast milk.
  • Contraception: Birth control pills may not work as well with Tybost so it is important to use another form of birth control like condoms along with your birth control.
  • Adults over 65: Based on the clinical studies of Tybost, no overall differences in safety or effectiveness were found between adults over 65 years and adults less than 65. However, some adults over 65 may be more sensitive to Tybost than others.
  • Children: The safety and effectiveness of Tybost in combination with atazanavir in children weighing less than 77 pounds (35 kilograms) have not been established. In addition, the safety and effectiveness of Tybost in combination with darunavir in children weighing less than 88 pounds (40 kilograms) have not been established. Clinical studies also noted that none of the children evaluated were under the age of 12.

Missed Dose

If you accidentally forgot your Tybost dose, take it as soon as you remember. If your next dose is in less than 12 hours, skip the missed dose and take the following dose at your next scheduled dosing time. Don't try to double up to make up for the missed dose.

Try to find ways that work for you to help yourself remember to keep your appointments and take your medication routinely. If you miss too many doses, your HIV-1 infection may become harder to treat.

Overdose: What Happens If I Take Too Much Tybost?

There is limited information available about Tybost overdose. Treatment of overdose with Tybost consists of general supportive measures, including monitoring of vital signs, as well as observation of the clinical status of the patient.

If you think you're experiencing an overdose or life-threatening symptoms, seek immediate medical attention.

What Happens If I Overdose on Tybost?

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

If someone collapses or isn't breathing after taking Tybost, call 911 immediately.

Precautions

Drug Content Provided and Reviewed by IBM Micromedex®

Your doctor will want to check your progress at regular visits, especially during the first few weeks that you take this medicine. Blood and urine tests may be needed to check for any unwanted effects.

This medicine should not be used together with atazanavir or darunavir if you are also using any of the following: alfuzosin (Uroxatral®), carbamazepine (Tegretol®), colchicine (Colcrys®), dronedarone (Multaq®), drospirenone/ethinyl estradiol (Yasmin®, Yaz®), indinavir (Crixivan®), irinotecan (Camptosar®), lomitapide (Juxtapid®), lovastatin (Altoprev®, Mevacor®), lurasidone (Latuda®), midazolam (Versed®), nevirapine (Viramune®), phenobarbital (Luminal®), phenytoin (Dilantin®), pimozide (Orap®), ranolazine (Ranexa®), rifampin (Rifadin®), sildenafil (Revatio®), simvastatin (Simcor®, Zocor®), St John's wort, triazolam (Halcion®), or ergot medicines (eg, dihydroergotamine, ergotamine, methylergonovine, Cafergot®, Migranal®). Doing so may cause serious unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment with this medicine. Certain birth control pills may not work as well to prevent pregnancy when used with this medicine. Use another form of birth control (eg, condoms, spermicide) along with your pills. If you think you have become pregnant while using this medicine, tell your doctor right away.

Using this medicine together with tenofovir DF may cause kidney problems (including Fanconi syndrome). Tell your doctor right away if you have bloody urine, decreased frequency or amount of urine, increased thirst, loss of appetite, lower back or side pain, nausea, vomiting, swelling of the face, fingers, or lower legs, trouble breathing, unusual tiredness or weakness, or weight gain.

This medicine does not decrease the risk of transmitting the HIV infection to others through sexual contact or by contaminated blood. Make sure you understand and practice safe sex, even if your partner also has HIV. Avoid sharing needles with anyone.

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 or vitamin supplements.

What Are Reasons I Shouldn’t Take Tybost?

You should not take Tybost in certain situations.

If you're allergic to Tybost or any of its ingredients, do not take it. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.

If you take any of the following medications, do not take Tybost:

  • Alpha 1-adrenoreceptor antagonist: Uroxatral (alfuzosin)
  • Antianginal (heart medications): Ranexa (ranolazine)
  • Antiarrhythmic (heart rhythm medications): Multaq (dronedarone)
  • Anticonvulsants (seizure medications): Tegretol (carbamazepine), Luminal (phenobarbital), Dilantin (phenytoin)
  • Anti-gout: Colcrys (colchicine)
  • Antimycobacterial (medicine used to treat Mycobacterium infections, like tuberculosis): Rifadin (rifampin)
  • Antineoplastics (anticancer drugs): Campto (irinotecan)--only applies to Tybost taken with Reyataz (atazanavir)
  • Antipsychotics: Latuda (lurasidone), Orap (pimozide)
  • Ergot derivatives: Migranal (dihydroergotamine), Ergomar (ergotamine), Methergine (methylergonovine)
  • Herbal products: St. John's wort (Hypericum perforatum)
  • Hormonal contraceptives: Yaz (drospirenone/ethinyl estradiol)--only applies to Tybost taken with Reyataz (atazanavir)
  • Lipid-modifying agents (cholesterol medications): Juxtapid (lomitapide), Mevacor (lovastatin), Zocor (simvastatin)
  • Non-nucleoside reverse transcriptase inhibitor (HIV medications): Viramune (nevirapine)--only applies to Tybost taken with atazanavir
  • Phosphodiesterase-5 (PDE-5) inhibitor: sildenafil when administered as Revatio for the treatment of pulmonary arterial hypertension
  • Protease inhibitor (HIV medication): Crixivan (indinavir)--only applies to Tybost taken with atazanavir
  • Sedative/hypnotics: Halcion (triazolam), orally administered Versed (midazolam)

Please let your healthcare provider know if you have kidney or liver problems because taking Tybost may worsen your condition.

What Other Medications Interact With Tybost?

Do not take Tybost with the following medications:

  • Alpha 1-adrenoreceptor antagonist: Uroxatral (alfuzosin)
  • Antianginal (heart medications): Ranexa (ranolazine)
  • Antiarrhythmic (heart rhythm medications): Multaq (dronedarone)
  • Anticonvulsants (seizure medications): Tegretol (carbamazepine), Luminal (phenobarbital), Dilantin (phenytoin)
  • Anti-gout: Colcrys (colchicine)
  • Antimycobacterial (medicine used to treat Mycobacterium infections, like tuberculosis): Rifadin (rifampin)
  • Antineoplastics (anticancer drugs): Campto (irinotecan)--only applies to Tybost taken with Reyataz (atazanavir)
  • Antipsychotics: Latuda (lurasidone), Orap (pimozide)
  • Ergot derivatives: Migranal (dihydroergotamine), Ergomar (ergotamine), Methergine (methylergonovine)
  • Herbal products: St. John's wort (Hypericum perforatum)
  • Hormonal contraceptives: Yaz (drospirenone/ethinyl estradiol)--only applies to Tybost taken with Reyataz (atazanavir)
  • Lipid-modifying agents (cholesterol medications): Juxtapid (lomitapide), Mevacor (lovastatin), Zocor (simvastatin)
  • Non-nucleoside reverse transcriptase inhibitor (HIV medications): Viramune (nevirapine)--only applies to Tybost taken with atazanavir
  • Phosphodiesterase-5 (PDE-5) inhibitor: sildenafil when administered as Revatio for the treatment of pulmonary arterial hypertension
  • Protease inhibitor (HIV medication): Crixivan (indinavir)--only applies to Tybost taken with atazanavir
  • Sedative/hypnotics: Halcion (triazolam), orally administered Versed (midazolam)

Use caution when taking Tybost with the following medications:

  • Lipitor (atorvastatin)
  • Stendra (avanafil)
  • Victrelis (boceprevir)
  • Tracleer (bosentan)
  • Buprenex (buprenorphine)
  • Suboxone (buprenorphine/naloxone)
  • Klonopin (clonazepam)
  • Plavix (clopidogrel)
  • Gengraf (cyclosporine)
  • Sprycel (dasatinib)
  • Sustiva (efavirenz)
  • Aptiom (eslicarbazepine)
  • Intelence (etravirine)
  • Afinitor (everolimus)
  • Pepcid (famotidine)
  • Durogesic (fentanyl)
  • Selzentry (maraviroc)
  • Methadose (methadone)
  • Viramune (nevirapine)
  • Tasigna (nilotinib)
  • Prilosec (omeprazole)
  • Trileptal (oxcarbazepine)
  • Trilafon (perphenazine)
  • Effient (prasugrel)
  • Seroquel (quetiapine)
  • Mycobutin (rifabutin)
  • Risperdal (risperidone)
  • Crestor (rosuvastatin)
  • Serevent Diskus (salmeterol)
  • Olysio (simeprevir)
  • Rapamune (sirolimus)
  • Prograf (tacrolimus)
  • Cialis (tadalafil)
  • Mellaril (thioridazine)
  • Brilinta (ticagrelor)
  • Ultram (tramadol)
  • Levitra (vardenafil)
  • Alkaban-AQ, Velban (vinblastine)
  • Oncovin (vincristine)
  • Birth control pills (including drospirenone/ethinyl estradiol)
  • Blood pressure medicine (including beta-blockers, calcium channel blockers)
  • Blood thinner (including apixaban, betrixaban, dabigatran, edoxaban, rivaroxaban, and warfarin)
  • Medicine for depression or mental health problems (including amitriptyline, desipramine, imipramine, nortriptyline, and TCAs)
  • Medicine for heart rhythm problems (including amiodarone, disopyramide, flecainide, mexiletine, propafenone, quinidine)
  • Medicine to treat an infection (including clarithromycin, erythromycin, itraconazole, ketoconazole, telithromycin, voriconazole)
  • Steroid medicine (including betamethasone, budesonide, ciclesonide, dexamethasone, fluticasone, methylprednisolone, mometasone, triamcinolone)

Take antacids at least 2 hours before or after you take this medicine.

This is not a complete list of medications that interact with Tybost.

Taking Tybost with atazanavir or darunavir, along with certain other medicines, can lead to severe or life-threatening side effects or could lead to death. Keep a list of your medications and show it to your healthcare provider and pharmacist when you get a new medicine.

Talk with your pharmacist or healthcare provider for more detailed information about medication interactions with Tybost.

Be sure to talk with your healthcare provider about any other medicines you take or plan to take, including over-the-counter, nonprescription products, vitamins, herbs, or plant-based medicines.

What Medications Are Similar?

There are no medications that are clinically similar to Tybost.

Frequently Asked Questions

  • What is Tybost used for?

    Tybost is used with other antiretrovirals to treat HIV-1 infection in adults or children.

  • When should you take Tybost?

    You need to take Tybost by mouth with food at the same time you take atazanavir or darunavir as prescribed by your healthcare provider.

  • Why is it important to talk with my healthcare provider before stopping Tybost?

    Do not change your dose or stop taking Tybost without first talking with your healthcare provider. If you stop the medicine even for a short time, your HIV-1 infection may become harder to treat.

How Can I Stay Healthy While Taking Tybost?

If you're taking Tybost, your HIV-1 infection has likely affected your life. You may have tried different approaches or treatments. While living with HIV does have its challenges, there are ways to help improve your quality of life. Refer below for some general tips to support your health:

  • Tybost is not an antiretroviral medicine and does not treat/cure the HIV-1 virus. You must keep taking Tybost along with atazanavir or darunavir and the other HIV-1 medications prescribed to you to control HIV-1 infection and decrease HIV-related illnesses.
  • Take all HIV-related medicines as prescribed by your healthcare provider.
  • Follow your scheduled healthcare provider's appointments while taking Tybost.
  • Tell your healthcare provider immediately if you notice any changes in your health.
  • Tybost will not keep you from giving HIV to others. Always practice safer sex, even if your partner also has HIV. Use a latex or polyurethane condom to lower the chance of sexual contact with semen, vaginal secretions, or blood.
  • Contact your healthcare provider or pharmacist when your supply is running low, so you do not run out.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for 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.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Food and Drug Administration. Tybost Label,

  2. Deeks ED. Cobicistat: a review of its use as a pharmacokinetic enhancer of atazanavir and darunavir in patients with HIV-1 infection. Drugs. 2014 Feb;74(2):195-206. doi: 10.1007/s40265-013-0160-x. PMID: 24343782.

  3. World Health Organization. HIV.