- Day 19 - after 4 days of dosing when steady state pharmacokinetics has been reached, subjects will attend for a 12 hour detailed pharmacokinetic visit where following witnessed administration of raltegravir 400 mg without food, blood sampling will be drawn at 0 (pre-dose), 0.5, 1, 2, 3, 4, 6, 8 and 12 hours post dose for the assessment of raltegravir plasma exposure.