BETHESDA, MD 28 August 2012—FDA on August 27 approved Stribild, a four-drug combination tablet marketed by Gilead Sciences Inc. for use in HIV-infected adults who have not previously undergone treatment for the infection.

A Gilead spokeswoman confirmed that the product will be available by the end of this week.

Stribild contains two previously approved medications plus elvitegravir—a new integrase inhibitor—and cobicistat, a so-called pharmacokinetic enhancer that inhibits cytochrome P-450 (CYP) isoenzyme 3A activity and boosts the effects of elvitegravir.

Each Stribild tablet contains 150 mg of elvitegravir; 150mg of cobicistat; 200 mg of emtricitabine, a nucleoside reverse transcriptase inhibitor; and 300 mg of tenofovir disoproxil fumarate, a nucleotide reverse transcriptase inhibitor.

Stribild is formulated for once-daily dosing with a single tablet, which should be taken with food, according to the product's labeling (PDF).

FDA described the product as "a complete treatment regimen for HIV infection."

But the company noted that elvitegravir and cobicistat as standalone agents are classified as investigational drugs whose safety and efficacy have not been established.

Gilead stated that it submitted applications to FDA in June for approval to market the two drugs as separate agents.

Stribild is contraindicated for coadministration with drugs that depend highly on CYP3A for clearance and, at higher-than-normal plasma concentrations, are associated with serious adverse events. Specific examples of these drugs are included in the labeling for the antiretroviral combination product.

Stribild is also contraindicated with drugs that strongly induce CYP3A.

The labeling for Stribild includes a boxed warning about the risks of lactic acidosis and severe liver disease during treatment with nucleoside analogues.

The boxed warning also emphasizes that Stribild is not indicated for the treatment of chronic hepatitis B virus (HBV) infection.

But severe exacerbations of hepatitis have been reported in patients who are coinfected with HIV and HBV and stopped taking emtricitabine or tenofovir disoproxil fumarate, according to the warning. Liver function should be closely monitored after discontinuation of Stribild and, if needed, anti-HBV therapy should be initiated.

In clinical trials, the most common adverse events reported among Stribild users were nausea and diarrhea. Less common but more serious adverse events included kidney impairment, decreased bone mineral density, redistribution of body fat, and immune reconstitution inflammatory syndrome.

Stribild is supplied in bottles containing 30 tablets each and bearing a label that states "ALERT: Find out about medicines that should NOT be taken with [Stribild]."

The product should be stored at controlled room temperature and dispensed only in its original container, which has a desiccant.