FDA Approves New Combination Pill for HIV Treatment for Some Patients

The Food and Drug Administration (FDA) has approved Stribild (elvitegravir, cobicistat, emtricitabine, tenofovir disoproxil fumarate), a new once-a-day combination pill to treat HIV-1 infection in adults who have never been treated for HIV infection.

Stribild contains two previously approved HIV drugs plus two new drugs, elvitegravir and cobicistat. Elvitegravir is an HIV integrase strand transfer inhibitor, a drug that interferes with one of the enzymes that HIV needs to multiply. Cobicistat, a pharmacokinetic enhancer, inhibits an enzyme that metabolizes certain HIV drugs and is used to prolong the effect of elvitegravir. The combination of emtricitabine and tenofovir disoproxil fumarate, approved in 2004 and marketed as Truvada, blocks the action of another enzyme that HIV needs to replicate in a persons body. Together, these drugs provide a complete treatment regimen for HIV infection.

Through continued research and drug development, treatment for those infected with HIV has evolved from multi-pill regimens to single-pill regimens, says Edward Cox, MD, MPH, director of the Office of Antimicrobial Products in FDAs Center for Drug Evaluation and Research. New combination HIV drugs like Stribild help simplify treatment regimens.

Stribilds approval is the latest HIV/AIDS-related action taken by the FDA this year. Other actions include approval of the first over-the-counter home-use rapid HIV test; approval of the first drug for pre-exposure prophylaxis in combination with safer sex practices to reduce the risk of sexually acquired HIV infection in adults at high risk; and commemoration of the full or tentative approvals of more than 150 antiretroviral products for the Presidents Emergency Plan for AIDS Relief (PEPFAR) to treat those in countries most affected by the HIV/AIDS epidemic.

The safety and effectiveness of Stribild was evaluated in 1,408 adult patients not previously treated for HIV in two double-blind clinical trials. Patients were randomly assigned to receive Stribild or Atripla, an HIV drug that contains Truvada and efavirenz, once daily in the first trial; and Stribild or Truvada plus atazanavir and ritonavir once daily in the second trial.

The studies were designed to measure the percentage of patients who had an undetectable amount of HIV in their blood at 48 weeks. Results showed between 88 percent and 90 percent of patients treated with Stribild had an undetectable amount of HIV in their blood, compared with 84 percent treated with Atripla and 87 percent treated with Truvada plus atazanavir and ritonavir.

Like labels of many other drugs used to treat HIV, Stribilds label carries a Boxed Warning alerting patients and health care professionals that the drug can cause a build up of lactic acid in the blood and severe liver problems, both of which can be fatal. The Boxed Warning also states that Stribild is not approved to treat chronic hepatitis B virus infection.

Common side effects observed in clinical trials include nausea and diarrhea. Serious side effects include new or worsening kidney problems, decreased bone mineral density, fat redistribution and changes in the immune system (immune reconstitution syndrome).  Stribilds label gives advice to health care providers on how to monitor patients for kidney or bone side effects.

Gilead Sciences, Stribilds manufacturer, is required to conduct additional studies to help further characterize the drugs safety in women and children, how resistance develops to Stribild, and the possibility of interactions between Stribild and other drugs.