STUDIES ON THE CHEMICAL REACTIVITY OF DICLOFENAC ACYL GLUCURONIDE WITH GLUTATHIONE: IDENTIFICATION OF DICLOFENAC-S-ACYL-GLUTATHIONE IN RAT BILE
| Autor: | Daniel J. Waldon, P E Sanders, Fengmei Hua, Joseph A. Ware, Charles G. Knutson, Mark P. Grillo |
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| Rok vydání: | 2003 |
| Předmět: |
Male
Diclofenac Metabolite Pharmaceutical Science Rats Sprague-Dawley chemistry.chemical_compound Glucuronides Transacylation In vivo medicine Animals Bile Incubation Chromatography High Pressure Liquid Pharmacology Chromatography biology Chemistry Glutathione In vitro Rats Biochemistry Enzyme inhibitor biology.protein medicine.drug |
| Zdroj: | Drug Metabolism and Disposition. 31:1327-1336 |
| ISSN: | 1521-009X 0090-9556 |
| Popis: | Diclofenac, a nonsteroidal anti-inflammatory drug, is metabolized to a reactive acyl glucuronide that has been proposed to mediate toxic adverse drug reactions associated with its use. In the present study, we examined the ability of diclofenac acyl glucuronide (D-1-O-G) to transacylate glutathione (GSH) in vitro in buffer and in vivo in rats. Thus, in vitro reactions of D-1-O-G (100 microM) with GSH (10 mM) at pH 7.4 and 37 degrees C showed a linear time-dependent formation of diclofenac-S-acyl-glutathione (D-SG, 3 microM/h) through 60 min of incubation, reaching a maximum of 3.7 microM after 2 h of incubation. The major reaction that occurred was acyl migration of D-1-O-G (t1/2, 54 min) to less reactive isomers. The D-SG thioester product was shown to be unstable by degrading primarily to 1-(2,6-dichlorophenyl)indolin-2-one and by hydrolysis to diclofenac. After administration of diclofenac to rats (200 mg/kg), bile was collected and analyzed for D-SG by liquid chromatography-tandem mass spectrometry. Results indicated the presence of D-SG, which was confirmed by coelution with synthetic standard and by its tandem mass spectrum. When the reactivity of D-SG (100 microM) was compared with D-1-O-G (100 microM) in vitro in reactions with N-acetylcysteine (NAC, 10 mM), results showed the quantitative reaction of D-SG with NAC after 30 min of incubation, whereas only approximately 1% of D-1-O-G reacted to form diclofenac-S-acyl-NAC at the same time point. Results from these studies indicate that GSH reacts with D-1-O-G in vitro, and presumably in vivo, to form D-SG, and that the product D-SG thioester is chemically more reactive in transacylation-type reactions than the D-1-O-G metabolite. |
| Databáze: | OpenAIRE |
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