The purpose of this study is to describe pharmacokinetics of maraviroc (MVC) 300 mg and atazanavir/ritonavir (ATV/r) 200/100 mg QD in HIV-infected stable patients.

The rational of this study is to save therapeutic options, toxicity and costs. The available literature shows that antiretroviral regimens that do not include a nucleoside backbone of tenofovir resulted in less bone and kidney toxicity. Atazanavir dosing 200/100 mg qd represents a simplification strategy correlated with virologic efficacy and a reduction of parameters toxicity associated. Maraviroc is suggested as a possible drug associated to PI/r in dual therapies. Even in this case, the available evidence supports the choice of the dosage of 300 mg/day.

Inclusion Criteria:

• age>18 years;
• confirmed HIV-antibodies positivity;
• signed informed consent;
• HIV-RNA <20 cp/ml for the last 24 months;
• no virological failures to PI regimens;
• no major PI resistance associated mutations;
• genotypic tropism for CCR5 co-receptor.

Exclusion Criteria:

• active opportunistic infections or neoplasms;
• need for drugs with known drug-drug interactions with included drugs;
• liver cirrhosis;
• any evidence of tropism for CXCR4 or dual infection;
• pregnancy;
• self-reported adherence<90%;
• HBsAg positivity;
• detectable HCV RNA.