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An Overview of Cobicistat (GS-9350)

October 25, 2010

Other Name(s): GS-9350
Drug Class: Opportunistic Infection and Other Drugs

Cobicistat, also known as GS-9350, is a type of medicine called a pharmacoenhancer or "boosting agent." This type of medicine works by raising blood levels of other drugs that are broken down by the same protein. Cobicistat, itself, does not have any antiviral activity.


Indications and Usage

Cobicistat is an investigational medicine that is not yet approved by the U.S. Food and Drug Administration (FDA) for use outside of clinical trials. It is being studied in combination with other drugs for the treatment of HIV infection.

Cobicistat is being studied in Phase III clinical trials as part of a single tablet fixed-dose combination regimen (also known as the "Quad" tablet). The "Quad" tablet contains the following four drugs: elvitegravir, cobicistat, emtricitabine, and tenofovir disoproxil fumarate.

In addition, cobicistat’s stand-alone role in boosting currently available HIV protease inhibitors is being studied in a clinical trial. This clinical trial involves studying cobicistat-boosted atazanavir, taken with emtricitabine/tenofovir disoproxil fumarate.

Cobicistat does not cure HIV infection and may not prevent you from developing HIV-related illnesses. Cobicistat does not prevent you from spreading HIV to other people.

Dosage Form/Administration

Cobicistat is currently used only in clinical trials. In these trials, cobicistat is taken by mouth. If you are currently taking cobicistat as part of a clinical trial, make sure to follow any specific instructions that have been given to you about participating in the trial. Unless your doctor or the research team tells you otherwise, please remember the following:

  • Continue your normal diet and take cobicistat with food.
  • If you forget to take a dose, take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take more than one dose of cobicistat in 1 day and do not take a double dose to make up for a missed dose.
  • Keep this medication in the container it came in, tightly closed, and out of reach of children. Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.
  • In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.
  • Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.
  • It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.


Individuals should tell a doctor about any medical problems before taking this medicine.

Possible Side Effects

If you are participating in a clinical trial or expanded access program, before taking cobicistat,

  • Tell your doctor and pharmacist if you are allergic to cobicistat or any other medications.
  • Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you more carefully for side effects.
  • Tell your doctor if you are pregnant or plan to become pregnant. If you become pregnant while taking cobicistat, call your doctor. Tell your doctor if you are breast-feeding. You should not breast-feed if you are infected with HIV or if you are taking cobicistat.

The following life threatening or serious side effects have been reported in clinical trials. Contact your doctor immediately if you experience:

  • Pneumonia (symptoms may include fever, chills, cough, unusually fast breathing, wheezing, difficulty breathing)
  • Skin rash
  • Loss of coordination
  • Anogenital warts
  • Vomiting
  • Variations in laboratory values

Other nonserious side effects have also been reported in clinical trials:

  • Abnormal dreams/nightmares
  • Fatigue
  • Dizziness
  • Diarrhea
  • Drowsiness
  • Headache
  • Anxiety
  • Nausea
  • Abdominal distension (swelling)
  • Rash
  • Flatulence

Cobicistat may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the FDA's MedWatch Adverse Event Reporting program online at or by phone 1-800-332-1088.

Drug Interactions

Certain medications or foods may interact with cobicistat.

Tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Your doctor may need to change the doses of your medications or monitor you more carefully for side effects.

Clinical Trials

Click here to search for trials that use Cobicistat.

Manufacturer Information

Gilead Sciences, Inc.
333 Lakeside Drive
Foster City, CA 94404
Phone: (650) 574-3000
Fax: (650) 578-9264

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This article was provided by AIDSinfo. Visit the AIDSinfo website to find out more about their activities and publications.
See Also
More on Cobicistat

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