- The participant who currently receives an enzyme inhibitor of CYP2C8 (gemfibrozil, ketoconazole, quercetin, trimethoprim), or enzyme inducer of CYP2C8 (cortisol, dexamethasone, phenobarbital, rifampin), or CYP3A4 substrate will not be eligible for randomization after assessing eligibility in stage two unless he/she will not be eligible for randomization after assessing eligibility in stage two unless he/she is willing to stop these drugs and possibly replace them with alternative therapies