<qa>  What is the name of the study that will be conducted on all potential participants?Procedures methods: An outpatient screening visit will be conducted on all potential participants to obtain informed consent and evaluate for eligibility. Once enrolled, all subjects will take 400 mg oral dose of raltegravir twice daily from Day 1 to Day 7. The healthy men enrolled in this study will undergo single-dose and multiple-dose pharmacokinetic sampling. Blood will be collected via peripheral IV at pre-dose, and at 1, 2, 3, 4, 6, 8 and 12 hours post-dose. Subjects will undergo two colonoscopies during sampling visits Day 1 and Day 7 for the purpose of obtaining gastrointestinal-associated lymphoid tissue GALT. Each subject will have his biopsy obtained at one of the following time points post-dose: 1, 2, 3, 4, 6, 8, and 12 hours. Seven to ten days after their last inpatient sampling visit, all subjects will complete a follow-up visit. 