title: Preclinical characterization of intestinal absorption and metabolism of promising anti-Alzheimer's dimer bis(7)-tacrine.
abstract: The present study aims to investigate the preclinical intestinal absorption of bis(7)-tacrine (B7T) using different absorption models. In addition, potential intestinal and liver first-pass metabolism was evaluated by in vitro incubation of B7T with rat intestine and liver microsome. Results showed that the permeability of B7T across artificial membrane was pH dependent with rapid diffusion achieved at both pH 6.8 and 7.4. However, the absorptive permeability of B7T in Caco-2 cell model was substantially lower than that in the artificial membrane accompanied with over 56% of B7T being trapped within Caco-2 cells. In the rat in situ intestinal perfusion model, B7T was subject to an extensive intestinal extraction (>90%) with extremely low concentration of B7T detected in mesenteric blood, which was further found to be associated with the high tissue binding (99.9%) of B7T. In vitro incubation of B7T with rat liver and intestinal microsomes revealed that hydroxylation of B7T might mainly occur in rat liver rather than intestine. In conclusion, B7T is expected to have a low oral bioavailability in vivo, which may be due to its poor intestinal permeability, significant tissue binding and hepatic hydroxylation metabolism.
authors: Department of Biochemistry, Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, SAR, PR China.
authors: Li
authors: L
authors: Zhang
authors: Hua
authors: H
authors: Yu
authors: Wen Ming
authors: WM
authors: Li
authors: Man Chun
authors: MC
authors: Cheung
authors: Yuan Ping
authors: YP
authors: Pang
authors: Ze Ming
authors: ZM
authors: Gu
authors: Kelvin
authors: K
authors: Chan
authors: Yi Tao
authors: YT
authors: Wang
authors: Zhong
authors: Z
authors: Zuo
authors: Yi Fan
authors: YF
authors: Han
mesh_terms: D000544:Alzheimer Disease / Q000188:drug therapy; D000818:Animals; D001711:Biotransformation; D018938:Caco-2 Cells; D002800:Cholinesterase Inhibitors / Q000378:metabolism / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D020719:Glucuronides / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007408:Intestinal Absorption / Q000502:physiology*; D007413:Intestinal Mucosa / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D018697:Nootropic Agents / Q000378:metabolism / Q000493:pharmacokinetics*; D010539:Permeability; D051381:Rats; D017207:Rats, Sprague-Dawley; D013056:Spectrophotometry, Ultraviolet; D013619:Tacrine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics
chemical_list: C122128:1,7-N-heptylene-bis-9,9'-amino-1,2,3,4-tetrahydroacridine; D002800:Cholinesterase Inhibitors; D020719:Glucuronides; D018697:Nootropic Agents; D013619:Tacrine; D003577:Cytochrome P-450 Enzyme System