Metabolism of Meloxicam in human liver involves cytochromes P4502C9 and 3A4.
1. The metabolism of Meloxicam (ME) and the cytochrome(s) P450 (CYPs) involved were analysed by using primary human hepatocytes, human liver microsomes and microsomes from recombinant human B-lymphoblastoid cell lines. 2. While human hepatocytes were capable of converting ME to a 5-hydroxymethyl metabolite (M7) and then to a 5-carboxyderivative (M5), human liver microsomes formed mostly only the 5-hydroxymethylderivative. The kinetics of the formation of M7 by human liver microsomes were biphasic with Km = 13.6 +/- 9.5 and 381 +/- 55.2 microM respectively. The corresponding Vmax were 33.7 +/- 24.2 and 143 +/- 83.9 pmol/min/mg protein respectively. 3. CYP2C9 and, to a much lesser extent, CYP3A4 were found to convert ME to M7. The involvement of 2C9 was demonstrated by inhibition of tolbutamide hydroxylase activity in the presence of ME, inhibition of ME metabolism by sulphaphenazole, correlation between ME metabolism and tolbutamide hydroxylase activity and active metabolism of ME by recombinant 2C9. The involvement of 3A4 was shown by inhibition of ME metabolism by ketoconazole, correlation between ME metabolism and nifedipine oxidase activity and metabolism of ME by recombinant 3A4. Kinetics of the formation of M7 by the individual enzymes resulted in a Km = 9.6 microM and Vmax = 8.4 pmol/min/mg protein for 2C9 and a Km = 475 microM and Vmax = 23 pmol/min/mg protein for 3A4.
Chesné
C
C
Inserm U 456, Détoxication et Réparation Tissulaire, Faculté de Pharmacie, Rennes, France.
Guyomard
C
C
Guillouzo
A
A
Schmid
J
J
Ludwig
E
E
Sauter
T
T
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism*; D001189:Aryl Hydrocarbon Hydroxylases; D065729:Cytochrome P-450 CYP2C9; D051544:Cytochrome P-450 CYP3A; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D006900:Hydroxylation; D007700:Kinetics; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D000077239:Meloxicam; D008862:Microsomes, Liver / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D039181:Steroid 16-alpha-Hydroxylase; D013250:Steroid Hydroxylases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013379:Substrate Specificity; D013843:Thiazines / Q000378:metabolism*; D013844:Thiazoles / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D000894:Anti-Inflammatory Agents, Non-Steroidal; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D013843:Thiazines; D013844:Thiazoles; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D013250:Steroid Hydroxylases; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C104464:CYP3A protein, human; D051544:Cytochrome P-450 CYP3A; D039181:Steroid 16-alpha-Hydroxylase; C510163:CYP3A4 protein, human; D000077239:Meloxicam