In vitro metabolism of MK-0767 [(+/-)-5-[(2,4-dioxothiazolidin-5-yl)methyl]-2-methoxy-N-[[(4-trifluoromethyl) phenyl]methyl]benzamide], a peroxisome proliferator-activated receptor alpha/gamma agonist. I. Role of cytochrome P450, methyltransferases, flavin monooxygenases, and esterases.
The metabolism of MK-0767, (+/-)-5-[(2,4-dioxothiazolidin-5-yl)methyl]-2-methoxy-N-[[(4-trifluoromethyl) phenyl]methyl]benzamide, a thiazolidinedione (TZD)-containing peroxisome proliferator-activated receptor alpha/gamma agonist, was studied in liver microsomes and hepatocytes from humans and rat, dog, and rhesus monkey, to characterize the enzyme(s) involved in its metabolism. The major site of metabolism is the TZD ring, which underwent opening catalyzed by CYP3A4 to give the mercapto derivative, M22. Other metabolites formed in NADPH-fortified liver microsomes included the TZD-5-OH derivative (M24), also catalyzed by CYP3A4, and the O-desmethyl derivative (M28), whose formation was catalyzed by CYP2C9 and CYP2C19. Metabolite profiles from hepatocyte incubations were different from those generated with NADPH-fortified microsomal incubations. In addition to M22, M24, and M28, hepatocytes generated several S-methylated metabolites, including the methyl mercapto (M25), the methyl sulfoxide amide (M16), and the methyl sulfone amide (M20) metabolites. Addition of the methyl donor, S-adenosyl methionine, in addition to NADPH, to microsomal incubations enhanced the turnover and resulted in metabolite profiles similar to those in hepatocyte incubations. Collectively, these results indicated that methyltransferases played a major role in the metabolism of MK-0767. Using enzyme-specific inhibitors, it was concluded that microsomal thiol methyltransferases play a more important role than the cytosolic thiopurine methyltransferase. Baculovirus-expressed human flavin-containing monooxygenase 3, as well as CYP3A4, oxidized M25 to M16, whereas further oxidation of M16 to M20 was catalyzed mainly by CYP3A4. Esterases were involved in the formation of the methyl sulfone carboxylic acids, minor metabolites detected in hepatocytes.
Department of Drug Metabolism, Merck Research Laboratories, P.O. Box 2000, Rahway, NJ 07065, USA. bindhu_karanam@merck.com
Bindhu V
BV
Karanam
Cornelis E C A
CE
Hop
David Q
DQ
Liu
Mike
M
Wallace
Dennis
D
Dean
Hiroya
H
Satoh
Masakatsu
M
Komuro
Katsuya
K
Awano
Stella H
SH
Vincent
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000145:classification / Q000187:drug effects / Q000502:physiology*; D001596:Benzylamines / Q000494:pharmacology; D002250:Carbon Radioisotopes; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004285:Dogs; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004950:Esterases / Q000502:physiology*; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007654:Ketoconazole / Q000494:pharmacology; D008253:Macaca mulatta; D008780:Methyltransferases / Q000502:physiology*; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000502:physiology*; D009249:NADP / Q000037:antagonists & inhibitors / Q000378:metabolism; D047493:PPAR alpha / Q000819:agonists* / Q000378:metabolism* / Q000494:pharmacology; D047495:PPAR gamma / Q000819:agonists* / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D012436:S-Adenosylmethionine / Q000037:antagonists & inhibitors / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013454:Sulfoxides / Q000378:metabolism; D013696:Temperature; D013844:Thiazoles / Q000378:metabolism* / Q000494:pharmacology; D045162:Thiazolidinediones / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology
D001596:Benzylamines; D002250:Carbon Radioisotopes; C487303:MK0767; D047493:PPAR alpha; D047495:PPAR gamma; D013438:Sulfhydryl Compounds; D013454:Sulfoxides; D013844:Thiazoles; D045162:Thiazolidinediones; C002569:2,3-dichloro-alpha-methylbenzylamine; D009249:NADP; D012436:S-Adenosylmethionine; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; D008780:Methyltransferases; D004950:Esterases; D007654:Ketoconazole