- Participants using the drugs listed below may not be randomized unless they are willing to stop the medications (and possibly change to alternative non-excluded medications to treat the same conditions) no less than 3 days prior to starting pioglitazone or placebo on this study; the use of the following drugs or drug classes is prohibited during pioglitazone/placebo treatment: participants taking inhibitors of CYP2C8 (gemfibrozil, ketoconazole, quercetin, trimethoprim), enzyme inducers of CYP2C8 (cortisol, dexamethasone, phenobarbital, rifampin), and CYP3A4 substrate