- The eligibility of patients taking medications that are potent inducers or inhibitors of the cytochrome P450, family 3, subfamily A, polypeptide 4 (CYP3A4) liver enzyme will be determined following a review of their case by the principal investigator; every effort should be made to switch patients taking such agents or substances to other medications; any identified agent needs to be stopped at least 2 weeks prior to study registration