Hydroxy pioglitazone is a major metabolite of the peroxisome proliferator-activated receptor γ (PPARγ) agonist pioglitazone (Item Nos. 71745 | 22263 | 10028). It is formed from pioglitazone by the cytochrome P450 (CYP) isoform CYP2C8 with minor contributions from CYP3A4. Hydroxy pioglitazone binds to PPARγ (Ki = 1.2 μM) and activates PPARγ in a time-resolved FRET (TR-FRET) assay (EC50 = 2.1 μM).