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Cobicistat “Booster” as Safe and Effective as Ritonavir

, by San Francisco AIDS Foundation

For nearly two decades, the antiretroviral drug ritonavir (Norvir) has been used to “boost” the blood levels of other HIV protease inhibitors, rendering them effective at smaller doses. Today, Gilead Sciences’ new boosting agent, cobicistat, is showing promise as a safe and effective alternative to ritonavir.

As reported in the July 1 issue of the Journal of Infectious Diseases, 48-week results from an advanced clinical trial pitting cobicistat against ritonavir (both taken along with tenofovir disoproxil fumarate/emtricitabine, the drugs in the Truvada combination pill) showed cobicistat to be “noninferior” to ritonavir in suppressing HIV replication. The two drugs’ safety profiles were also similar.

What’s next for this “pharmacoenhancer”? The drug, which works solely as a booster and has no anti-HIV activity of its own, is already on pharmacy shelves as part of the combination regimen Stribild, but approval of stand-alone cobicistat hit a speedbump last May. The U.S. Food and Drug Administration denied approval of the New Drug Applications for cobicistat and the novel integrase inhibitor elvitegravir (also a component of Stribild) due to “deficiencies in documentation and validation of certain quality testing procedures and methods,” according to a statement from Gilead. The pharmaceutical company is working with the FDA to address these issues and move the applications forward.

For details on the latest safety and efficacy data for cobicistat, see Liz Highleyman’s summary article, excerpted below and available in full at HIVandHepatitis.com.

Cobicistat Booster Is a Safe and Effective Alternative to Ritonavir

By Liz Highleyman

May 30, 2013

The novel pharmacoenhancer cobicistat boosts blood levels of atazanavir (Reyataz) as well as ritonavir (Norvir) and is generally safe and well-tolerated over 48 weeks, according to final study results published in the July 1, 2013, Journal of Infectious Diseases.

Some antiretroviral drugs—including most HIV protease inhibitors, the integrase inhibitor elvitegravir, and certain direct-acting hepatitis C virus drugs—have trouble reaching effective levels in the body. Boosters like cobicistat and ritonavir raise concentrations by inhibiting activity of the CYP3A enzyme in the liver, which slows drug processing. Unlike ritonavir, Gilead Sciences’ cobicistat is not itself active against HIV.

Joel Gallant from Johns Hopkins University School of Medicine and colleagues conducted a randomized, controlled Phase 3 trial (Study 114; NCT01108510) comparing the safety and efficacy of cobicistat versus ritonavir, both used as part of a first-line antiretroviral regimen with atazanavir and tenofovir disoproxil fumarate/emtricitabine (the drugs in Truvada). Data were previously presented at scientific meetings including the 2012 International AIDS Conference, and final results have now been published….

Click here to read the full summary article at HIVandHepatitis.com.

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