Based upon Pfizer's reports on premarketing and post marketing studies of Maraviroc and our review of the literature, no dose adjustment is necessary in patients with even mild-to-moderate renal impairment. The drug does not affect the QT interval. At high doses (600mg or more), it may induce orthostatic hypotension, so it is recommended that users who also take an anti-hypertensive medication be asked about symptoms of orthostatic hypotension. Of note, 8% of patients in active and placebo drug groups described orthostatic symptoms in a large trial. In HIV trials, 1.3% of subjects had cardiovascular events, more than in the placebo group, but the link to the drug was unclear and symptoms occurred only in those with known cardiac disease. Also, no greater incidence of infection, rash or other CNS symptoms was noted in these subjects. An occasional Stevens-Johnson syndrome and drug rash with eosinophilia and systemic symptoms did occur (seen only in post marketing surveillance, not in controlled trials), so complaints of rash, fever, joint or muscle aches, blisters, facial edema, etc. will be part of our weekly phone call surveillance plan. Participants will be told to stop their medication immediately should such symptoms occur and their physician notified. Of note, St John's wort should not be used with the medication since it decreases the concentration of Maraviroc.