P136 In Vitro Evaluation of Novel PPAR-Sparing Insulin Sensitizers and Their Pharmacologically Active Hydroxy Metabolites as Inducers of CYP450 Expression in Cultured Human Hepatocytes

Wade J. Adams , Metabolic Solutions Development Company, Kalamazoo, MI
Immaculate Amunon , Enzyme Induction Department, XenoTech, LLC, Lenexa, KS
Jerry R. Colca , Metabolic Solutions Development Company, Kalamazoo, MI
Jason N. Neat , Enzyme Induction Department, Metabolic Solutions Development Company, Kalamazoo, MI
MSDC0602 (5-{4-[2-(3-methoxyphenyl)-2-oxoethoxy]benzyl}-1,3-thiazolidine-2,4-dione]) and MSDC-0160 ([5-[4-[2-(5-ethyl-2-pyridyl)-1-oxoethoxy]phenylmethyl]-1,3-thiazolidine-2,4-dione]) are being developed for the treatment of Type 2 diabetes. They are insulin sensitizers that are related to the thiazolidinedione pioglitazone (ACTOS) except both compounds have significantly reduced ability to activate the nuclear transcription factor PPAR. These compounds exert their pharmacology by selectively modulating mitochondrial metabolism resulting, among other things, in improved insulin sensitivity and an increase in brown adipose tissue. The PPAR-sparing nature of these compounds and their pharmacologically active hydroxy metabolites (MSDC-0597 and MSDC-0037, respectively) may provide increased therapeutic ratio in clinical practice. Therapeutic Cmax of the parent compounds and hydroxy metabolites in humans are expected to be ? 1.2 and ? 12 M, respectively. The potential of MSDC-0602 and MSDC-0160 to induce CYP450 expression was assessed in primary cultures of fresh human hepatocytes in the current study. To evaluate induction, freshly isolated human hepatocytes (n=3) were cultured and treated daily for three consecutive days with vehicle control, one of three concentrations of MSDC-0602 (1.2, 12 or 120M) or MSDC-0160 (1.2, 12 or 120M), or one of three known prototypical CYP inducers, namely omeprazole (AhR, CYP1A2, 100M), phenobarbital (CAR, CYP2B6, 750M) and rifampin (PXR, CYP3A4/5, 10M) and then evaluated for CYP activities (namely, CYP1A2, 2B6 and 3A4/5). In addition, the ability of either test compound to cause toxicity was assessed both by daily microscopic evaluation, and by the release of lactate dehydrogenase (LDH) in to the culture medium, to which, neither MSDC-0602, nor MSDC-0160 caused any detectible toxicity, by either method. Under conditions where the prototypical inducers caused anticipated increases in CYP activity, neither MSDC-0602 nor MSDC-0160 induced (less than or equal two fold) CYP1A2 activity (at concentrations up to 120 M), CYP2B6 activity (at concentrations up to 12 M) or CYP3A4 (at concentrations up to 12 M). However, at higher concentrations (120 M) MSDC-0602 and MSDC-0160 induced both CYP2B6 (2.71- and 3.84-fold, respectively) and CYP3A4/5 (9.76- and 10.6-fold, respectively) activity and in some cases, the induction was more than 20% or 40% of the positive control effect in one or more of the human preparations. These data suggest that although MSDC-0602 and MSDC-0160 induced CYP2B6 and 3A4/5 activity, they do so only at concentrations which are greater than or equal 10x the expected therapeutic steady state Cmax.