- Enrollment in an experimental protocol with concomitant use of drugs known to impact or be impacted in terms of pk or drug-drug interactions with either raltegravir or maraviroc. This includes inducers of UGT1A1 ( such as rifampin, phenytoin, Phenobarbital rifabutin, St. John's wart) as well as CYP3A inhibitors (such as ketoconazole, itraconazole, clarithromycin , nefazodone and telithromycin) and CYP3A inducers (such as rifampin, carbamazepine, Phenobarbital and phenytoin)