Pharmacokinetics of the combination raltegravir/atazanavir in HIV-1-infected patients

ObjectivesTo evaluate the use of raltegravir with unboosted atazanavir in combination with one nucleoside reverse transcriptase inhibitor (NRTI) (lamivudine or emtricitabine) as a potentially well-tolerated once-daily (qd) maintenance regimen. MethodsWe compared the pharmacokinetics of raltegravir 400mg twice daily (bid) with raltegravir 800mg qd in HIV-infected patients (n=17) on unboosted atazanavir (600mg qd) in combination with lamivudine or emtricitabine. ResultsThe area under the plasma concentration vs. time curve for a dose interval t (AUC(0-t)) of 800mg qd divided by 2 was not significantly different from the AUC(0-t) of 400mg bid (P=0.664) but the minimum concentration (C-min) was 72% lower with the qd regimen (P=0.002). The regimen was well tolerated and the viral load remained undetectable in all patients during the 6 weeks of the study follow-up. ConclusionsA qd regimen of raltegravir 800mg, atazanavir 600mg and lamivudine or emtricitabine resulted in favourable pharmacokinetic profiles and good short-term safety and efficacy data. Larger phase IIb studies are needed to explore this novel regimen.