The disposition and metabolism of rofecoxib, a potent and selective cyclooxygenase-2 inhibitor, in human subjects.
The disposition and metabolism of rofecoxib, a selective cyclooxygenase-2 inhibitor, were examined in healthy human subjects and in cholecystectomy patients. After oral administration of [(14)C]rofecoxib (125 mg, 100 micro Ci) to healthy subjects, the mean concentrations of total radioactivity and rofecoxib in plasma as a function of time indicated that the t(max) was achieved at 9 h postdose. After t(max), levels of both radioactivity and rofecoxib decreased in a parallel, exponential fashion (effective t(1/2) approximately equal 17 h). A similar result was obtained after oral administration of [(14)C]rofecoxib (142 mg, 100 micro Ci) to cholecystectomy patients equipped with an L-tube. In healthy subjects, radioactivity was recovered predominantly from the urine (71.5% of dose), with a small amount excreted in feces (14.2%). In patients with an L-tube, half the radioactive dose was recovered in feces, with a lesser amount excreted in urine (28.8%) and a negligible fraction in bile (1.8%). Rofecoxib underwent extensive metabolism in humans, and very little parent drug was recovered unchanged in urine (<1%). Products resulting from both oxidative and reductive pathways were identified by a combination of (1)H NMR and liquid chromatography-tandem mass spectrometry analyses, and included rofecoxib-3',4'-trans-dihydrodiol, 4'-hydroxyrofecoxib-O-beta-D-glucuronide, diastereomeric 5-hydroxyrofecoxib-O-beta-D-glucuronide conjugates, 5-hydroxyrofecoxib, rofecoxib-erythro-3,4-dihydrohydroxy acid, and rofecoxib-threo-3,4-dihydrohydroxy acid. Interconversion of rofecoxib and 5-hydroxyrofecoxib appeared not to be a quantitatively important pathway of rofecoxib disposition in human subjects, in contrast to previous findings in rats.
Halpin
Rita A
RA
Department of Drug Metabolism, Merck Research Laboratories, West Point, Pennsylvania 19486, USA.
Porras
Arturo G
AG
Geer
Leslie A
LA
Davis
Margaret R
MR
Cui
Donghui
D
Doss
George A
GA
Woolf
Eric
E
Musson
Donald
D
Matthews
Catherine
C
Mazenko
Ralph
R
Schwartz
Jules I
JI
Lasseter
Kenneth C
KC
Vyas
Kamlesh P
KP
Baillie
Thomas A
TA
D000284:Administration, Oral; D001646:Bile / Q000737:chemistry; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000378:metabolism / Q000493:pharmacokinetics* / Q000652:urine; D004305:Dose-Response Relationship, Drug; D005243:Feces / Q000737:chemistry; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors*; D007783:Lactones / Q000378:metabolism / Q000493:pharmacokinetics* / Q000652:urine; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases; D013450:Sulfones; D014018:Tissue Distribution
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D007527:Isoenzymes; D007783:Lactones; D008565:Membrane Proteins; D013450:Sulfones; C116926:rofecoxib; C445439:5-hydroxyrofecoxib; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases