Pharmacokinetics of Low Dose Raltegravir

Twenty four HIV-infected volunteers on stable doses of RAL 400 mg BID for at least 3 months and with undetectable viral load will be enrolled. On Day 1, all 24 subjects will attend the first intensive PK collection for RAL 400 mg BID and the blood samples will be drawn at T = 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 6.0, 8.0, 10.0, and 12.0 hour post medication. All 24 subjects will be randomised (1:1) to either Group A (RAL 400 mg OD) or Group B (RAL 800 mg OD) for 14 days. On day 15, a second 24 hour intensive PK will be carried out and the blood samples will be drawn. After 2nd intensive PK, the subjects will switch to the other dosing regimen. Subjects in group A will receive RAL 800 mg OD and group B will receive RAL 400 mg OD for another 14 days. On day 29, the third 24 hour intensive PK will be carried out. After the 3rd intensive PK, all 24 subjects will be switched back to the initial regimen of RAL 400 mg BID.