Hypothesis: the intracellular concentrations of raltegravir (RAL) and etravirine (ETV) administrated as 800 and 400 mg once a day, respectively, are similar to those obtained with the standard doses of 400 and 200 mg/12h, respectively.

Objective: To analyze the plasma and intracellular concentrations of RAL and ETV administrated as 800 and 400 mg once daily respectively compared with standard doses of 400 and 200 mg/12h, respectively, and if they support its once daily administration.

Objective: To analyze the plasma and intracellular concentrations of RAL and ETV administrated as 800 and 400 mg once daily respectively compared with standard doses of 400 and 200 mg/12h, respectively, and if they support its once daily administration.

Method: Phase IV, prospective, open labelled clinical trial with a planned duration of 24 weeks in which 16 patients from Hospitales Universitarios Virgen del Rocío will be enrolled. A 12 hours pharmacokinetic profile (immediately before and after 1, 2, 3, 4, 6, 8, 10 and 12 h) will be obtained after a supervised drug intake while taking RAL or ETV bid. Afterwards,the patients will take RAL or ETV once a day for 7 - 10 days. Subsequently, a new pharmacokinetic profile (predose and after 1, 2, 3, 4, 6, 8, 10, 12, 16, 20 and 24 h after a supervised drug intake) will be obtained.

Inclusion Criteria:

• Adult HIV-1-infected patients taking raltegravir- or etravirine-based antiretroviral regimens

Exclusion Criteria:

• Pregnancy
• Concomitant use of drugs that have potential interactions with raltegravir or etravirine pharmacokinetics
• Cirrhosis with clinical or analytic data of liver failure.
• Clinical history suggesting malabsorption or presence of diarrhea (> 3 stools / day) that could interfere with the absorption of study drugs.