title: Disposition and metabolic profiling of [(14)C]cerlapirdine using accelerator mass spectrometry.
abstract: Cerlapirdine (SAM-531, PF-05212365) is a selective, potent, full antagonist of the 5-hydroxytryptamine 6 (5-HT6) receptor. Cerlapirdine and other 5-HT6 receptor antagonists have been in clinical development for the symptomatic treatment of Alzheimer's disease. A human absorption, distribution, metabolism, and excretion study was conducted to gain further understanding of the metabolism and disposition of cerlapirdine. Because of the low amount of radioactivity administered, total (14)C content and metabolic profiles in plasma, urine, and feces were determined using accelerator mass spectrometry (AMS). After a single, oral 5-mg dose of [(14)C]cerlapirdine (177 nCi), recovery of total (14)C was almost complete, with feces being the major route of elimination of the administered dose, whereas urinary excretion played a lesser role. The extent of absorption was estimated to be at least 70%. Metabolite profiling in pooled plasma samples showed that unchanged cerlapirdine was the major drug-related component in circulation, representing 51% of total (14)C exposure in plasma. One metabolite (M1, desmethylcerlapirdine) was detected in plasma, and represented 9% of the total (14)C exposure. In vitro cytochrome P450 reaction phenotyping studies showed that M1 was formed primarily by CYP2C8 and CYP3A4. In pooled urine samples, three major drug-related peaks were detected, corresponding to cerlapirdine-N-oxide (M3), cerlapirdine, and desmethylcerlapirdine. In feces, cerlapirdine was the major (14)C component excreted, followed by desmethylcerlapirdine. The results of this study demonstrate that the use of the AMS technique enables comprehensive quantitative elucidation of the disposition and metabolic profiles of compounds administered at a low radioactive dose.
authors.affiliation: Pfizer, Inc., Groton, Connecticut (S.T., L.L., R.S.O.), and Collegeville, Pennsylvania (S.R.); Xceleron, Inc., Germantown, Maryland (M.S., Y.S.) and University of Dundee, Scotland, UK (Y.S.) susanna.tse@pfizer.com.
authors.forename: Susanna
authors.initials: S
authors.lastname: Tse
authors.affiliation: Pfizer, Inc., Groton, Connecticut (S.T., L.L., R.S.O.), and Collegeville, Pennsylvania (S.R.); Xceleron, Inc., Germantown, Maryland (M.S., Y.S.) and University of Dundee, Scotland, UK (Y.S.).
authors.forename: Louis
authors.initials: L
authors.lastname: Leung
authors.affiliation: Pfizer, Inc., Groton, Connecticut (S.T., L.L., R.S.O.), and Collegeville, Pennsylvania (S.R.); Xceleron, Inc., Germantown, Maryland (M.S., Y.S.) and University of Dundee, Scotland, UK (Y.S.).
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Raje
authors.affiliation: Pfizer, Inc., Groton, Connecticut (S.T., L.L., R.S.O.), and Collegeville, Pennsylvania (S.R.); Xceleron, Inc., Germantown, Maryland (M.S., Y.S.) and University of Dundee, Scotland, UK (Y.S.).
authors.forename: Mark
authors.initials: M
authors.lastname: Seymour
authors.affiliation: Pfizer, Inc., Groton, Connecticut (S.T., L.L., R.S.O.), and Collegeville, Pennsylvania (S.R.); Xceleron, Inc., Germantown, Maryland (M.S., Y.S.) and University of Dundee, Scotland, UK (Y.S.).
authors.forename: Yoko
authors.initials: Y
authors.lastname: Shishikura
authors.affiliation: Pfizer, Inc., Groton, Connecticut (S.T., L.L., R.S.O.), and Collegeville, Pennsylvania (S.R.); Xceleron, Inc., Germantown, Maryland (M.S., Y.S.) and University of Dundee, Scotland, UK (Y.S.).
authors.forename: R Scott
authors.initials: RS
authors.lastname: Obach
mesh_terms: D000284:Administration, Oral; D000328:Adult; D002250:Carbon Radioisotopes / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005243:Feces / Q000737:chemistry; D006801:Humans; D007191:Indazoles / Q000378:metabolism*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D008657:Metabolic Clearance Rate / Q000502:physiology; D055442:Metabolome / Q000502:physiology*; D055432:Metabolomics / Q000379:methods; D008875:Middle Aged; D011985:Receptors, Serotonin / Q000378:metabolism; D012701:Serotonin / Q000378:metabolism; D013450:Sulfones / Q000378:metabolism*; D055815:Young Adult
chemical_list: D002250:Carbon Radioisotopes; D007191:Indazoles; D011985:Receptors, Serotonin; C581984:SAM-531; D013450:Sulfones; C097216:serotonin 6 receptor; D012701:Serotonin; D003577:Cytochrome P-450 Enzyme System