What to Know About Stribild (Elvitegravir, Cobicistat, Emtricitabine, Tenofovir DF)

Quad Pill Used to Treat HIV Infection

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Stribild, also known as the Quad pill, is a single-tablet, fixed-dose combination drug used daily to treat HIV in adults. It is comprised of four different antiretroviral drug agents:

  • Elvitegravir, an integrase inhibitor
  • Cobicistat, an HIV booster drug
  • Emtricitabine, a nucleotide reverse transcriptase inhibitor (NRTI)
  • Tenofovir disoproxil fumarate (TDF), another NRTI

Stribild is an all-in-one treatment option that does not require any other antiretroviral medications. It has relatively few side effects but cannot be used in everyone, particularly those with certain pre-existing health conditions.

Man holding HIV medication cocktail, close-up
Bruce Forster / Getty Images

Stribild does not cure HIV. Rather, it suppresses the virus to undetectable levels, thereby preventing disease progression. The drugs in Stribild do so by blocking enzymes called reverse transcriptase and integrase that the virus needs to replicate.

In November 2015, a newer formulation of Stribild, called Genvoya, was licensed by the FDA, replacing TDF with an "improved" version of the drug called tenofovir alafenamide (TAF).

As a prodrug (an inactive substance metabolized by the body to create an active drug), TAF exposes the body to a lower dose of tenofovir and reduces the risk of kidney impairment sometimes seen in users of TDF.

Uses

Stribild was approved by the Food and Drug Administration (FDA) in August 2012 for use in adults 18 and over who are starting antiretroviral therapy for the first time. It can also be used in adults with undetectable viral loads who are changing treatment due to drug intolerance or other reasons.

There are no generic versions or off-label uses of Stribild.

Before Taking

Whether you're starting therapy for the first time or changing treatment, your doctor will perform tests to determine which drugs you are most sensitive to. This is because drug resistance is common in people with HIV, even those starting treatment.

There are two tests commonly used to determine your sensitivity to HIV drugs:

  • Genetic resistance testing, the preferred test, can detect the types and number of resistant mutations your virus has. Based on the findings, the lab can predict with a high degree of accuracy which drugs you are sensitive to.
  • Phenotypic testing, typically used after a treatment failure, directly exposes the virus to all available antiretroviral drugs to see which ones work best.

Genetic resistance testing is essential for both newly treated and treatment-experienced people. Even those who are newly infected may have picked up a resistant virus through sex, shared needles, or other modes of transmission.

Precautions and Contraindications

Stribild should never be used in someone who has had a prior hypersensitive reaction to any of the drugs in the tablet.

There are others who should avoid Stribild or use it with caution:

  • Kidney disease: Stribild should be used with caution in people with chronic kidney disease and avoided in those with a creatinine clearance of less than 70 milliliters per minute (mL/min).
  • Osteoporosis: Tenofovir can cause bone mineral loss and may need to be avoided in people with osteoporosis or a history of pathologic fractures. Bone mineral density (BMD) testing should be performed prior to treatment for those at risk.

Other Combination Antiretroviral Drugs

In addition to Stribild, there are 12 other combination drugs approved by the FDA that can be taken in a once-daily dose:

In January 2021, the FDA approved the first once-monthly antiretroviral combination regimen called Cabenuva, comprised of two separate injections of the drugs cabotegravir and rilpivirine.

Dosage

Stribild is manufactured as a green, oblong, film-coated tablet embossed with "GSI" on one side and with the number "1" contained in a square on the other. Each tablet is comprised of 150 milligrams (mg) of elvitegravir, 150 mg of cobicistat, 200 mg of emtricitabine, and 300 mg of tenofovir DF.

Stribild is taken once daily by mouth with food. It is not taken with any other antiretroviral drug used to treat HIV.

How to Take and Store

Elvitegravir requires fat to be metabolized and absorbed in the bloodstream. As such, a high-fat meal is preferred over a low-fat meal when taking Stribild. Always swallow the pill whole; do not crush, split, or chew it.

Stribild can be safely stored at room temperature, ideally between 68 and 72 degrees F (20 and 25 degrees C). Keep the tablets in their original light-resistant container in a cool, dry drawer or cabinet. Do not store in your glove compartment or on a sunny windowsill.

If you miss a dose, take it as soon as you remember. If it is near the time of your next dose, skip the original dose and continue as normal. Never double up doses.

Side Effects

Side effects are common with any drug. Those associated with Stribild tend to be mild and transient, typically resolving in a week or two as your body adapts to treatment. Even so, some people may experience intolerable and even life-threatening side effects that require immediate termination of treatment.

Common

Common side effects of Stribild include (by order of frequency):

  • Nausea (16%)
  • Diarrhea (12%)
  • Abnormal dreams (9%)
  • Headache (7%)
  • Fatigue (4%)
  • Rash (4%)
  • Dizziness (3%)
  • Insomnia (3%)
  • Flatulence (2%)
  • Sleepiness (1%)

Severe

Stribild has been known in rare cases to cause severe side effects. Some of these occur in people with pre-existing health conditions, while others occur in people with no predisposing health factors. Among them:

  • Kidney failure most commonly occurs in people with pre-existing kidney disease or those taking nephrotoxic drugs (medications toxic to the kidneys).
  • Hepatomegaly with steatosis, the abnormal enlargement of the liver, is sometimes experienced by TDF users, most commonly those with pre-existing liver disease.
  • Osteomalacia, the abnormal softening of bone, is associated with TDF use. Osteomalacia typically manifests with bone pain and an increased risk of fractures.
  • Lactic acidosis is the potentially life-threatening buildup of lactic acid in the bloodstream. This has been to known to occur with many NRTIs, including TDF.
  • Inflammatory reconstitution inflammatory syndrome (IRIS), a paradoxical response in which the initiation of therapy triggers extreme inflammation due to the "unmasking" of an infection or an overreaction of the immune system. has been reported with Stribild.

Warnings and Interactions

Stribild carries a black box warning advising consumers of the risk of a potentially severe flare-up of hepatitis symptoms in people coinfected with hepatitis B if treatment is stopped. If you stop taking Stribild, your liver function should be monitored and anti-hepatitis B treatment started should a flare-up occur. (Hepatitis B testing is recommended prior to the start of therapy to check for undiagnosed infection.)

Because kidney failure has been known to occur in users of TDF with no prior history of kidney disease, routine kidney function tests are considered vital. If the estimated creatinine clearance ever falls below 50 mL/min, treatment should be stopped and changed.

Stribild is a Pregnancy Category B drug, meaning that animal studies have shown no evidence of fetal harm but well-controlled human studies are lacking. While Stribild is generally considered safe during pregnancy, speak with your doctor to fully understand the benefits and potential risks if you are pregnant or planning to get pregnant.

Drug Interactions

Stribild is known to interact with many drugs. In some instances, the interaction can cause the Stribild concentration to drop in the bloodstream, reducing the effectiveness of the drug. In others, the interaction may increase the risk of liver or kidney toxicity and other adverse events.

The FDA advises against the use of the following drugs with Stribild:

  • Uroxatral (alfuzosin)
  • Propulsid (cisapride)
  • Tegretol (carbamazepine)
  • Ergot-containing medicines, including DHE 45 (dihydroergotamine) , Ergostat (ergotamine), and Ergotrate (methylergonovine)
  • Latuda (lurasidone)
  • Revatio (sildenafil)
  • Rifadin (rifampin) and other anti-tuberculosis drugs
  • St. John's wort
  • Statin drugs like Mevacor (lovastatin) and Zocor (simvastatin)

Other drugs can interact with Stribild and may require a dose adjustment, drug substitution, or the separation of doses by several hours.

To avoid interactions, always advise your doctor about any medication you take, whether it is prescription, over-the-counter, nutritional, naturopathic, or recreational.

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Article Sources
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