NRTI-sparing antiretroviral regimen of unboosted atazanavir (Reyataz) plus raltegravir (Isentress) suppresses HIV in treatment-naive patients as well as standard 3-drug combinations, but its twice-daily dosing, side effects, and low barrier to resistance limit its appeal. For treatment-experienced people already doing well on atazanavir triple therapy, however, the dual regimen may be an attractive simplification option.
According to the latest U.S. antiretroviral treatment guidelines
, preferred first-line regimens consist of a NNRTI, a ritonavir-boosted protease inhibitor, or the integrase inhibitor raltegravir, all combined with 2 nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs). NRTIs and ritonavir can cause multiple drug toxicities, however, prompting researchers to explore alternative regimens.
I bet this nucleoside-free regimen could do even better when it comes to side effects if the Reyataz (atanazavir) dose was cut to 150 mg twice a day instead of the 300 mg twice a day. However, this lower dose of atanazavir has not been tested in combination with raltegravir, so patients should not take the risk to experiment with it.
I think twice a day dosing is not a big deal, no matter how bad pharmaceutical companies and clinicians make twice a day dosing to be. Many patients will be happy to take a twice a day combination if they do not have to be exposed to nucleosides.
I really believe this is a great option for patients who do not want to take nucleosides due to kidney and bone issues, or who have hypersensitivity to abacavir.
Both raltegravir and atanazavir boost each other, but it seems that raltegravir boosts atanazavir so much that 20 percent of patients experience high bilirubin, a common side effect of atanazavir.
Note: Nucleoside-free combos are not recommended with patients coinfected with Hepatitis B and HIV (Tenofovir, a nucleoside analog, is also a treatment for Hepatitis B)