In December, the U.S. Food and Drug Administration (FDA) approved AbbVie's interferon-free hepatitis C virus (HCV) regimen Viekira Pak to treat people with genotype 1 of the virus, including those coinfected with HIV.

The Viekira Pak regimen consists of two kinds of pills. One is a combination tablet taken once daily that contains the antivirals ombitasvir and paritaprevir, as well as the HIV antiretroviral (ARV) ritonavir as a “boosting agent.” The other pill is the antiviral dasabuvir taken twice daily. People with genotype 1a, as well as those who have cirrhosis or have had a liver transplant, should take Viekira Pak with ribavirin. Treatment runs for 12 weeks, although certain people with genotype 1a of hep C and cirrhosis are advised to continue for 24 weeks.

While highly effective at curing hep C, the therapy is not necessarily the best option for people on treatment for HIV, because only a few ARVs have proved to be safe to take with Viekira Pak.

“While some may be able to have their ARV regimen changed to accommodate these restricted options,” says Daniel Fierer, MD, an infectious disease specialist at Mount Sinai in New York City, “the alternative HCV treatment, [Gilead Sciences'] Harvoni [ledipasvir/sofosbuvir], has few drug interactions with ARVs, so it is difficult to justify making potentially risky changes in ARVs when a safe and effective alternative treatment for hepatitis C is available that does not require such a change.”