title: Blood-brain barrier penetration of novel pyridinealdoxime methiodide (PAM)-type oximes examined by brain microdialysis with LC-MS/MS.
abstract: To develop a new reactivator of inhibited acetylcholinesterase (AChE) that can easily penetrate the blood-brain barrier (BBB), BBB penetration of 6 known and novel pyridinealdoxime methiodide (PAM)-type oximes (alkylPAMs) with relatively high reactivation activities was examined by in vivo rat brain microdialysis with liquid chromatography-mass spectrometry (LC-MS/MS). The 50% lethal dose (LD(50)) of alkylPAMs was intravenously determined for Wistar rats, then the limit of detection, quantification range and linearity of the calibration curve of the alkylPAMs in dialysate and blood were determined by LC-MS/MS. Following 10% LD(50) intravenous administration of the alkylPAMs, 4-[(hydroxyimino) methyl]-1-(2-phenylethyl) pyridinium bromide (4-PAPE) and 4-[(hydroxyimino) methyl]-1-octylpyridinium bromide (4-PAO) appeared in the dialysate. Striatal extracellular fluid/blood concentration ratios were 0.039+/-0.018 and 0.301+/-0.183 (mean+/-SEM), respectively, 1 h after treatment. This is the first report of BBB penetration of 4-PAPE, and the concentration ratio was smaller than that of 2-PAM. The mean BBB penetration of 4-PAO was approximately 30%, indicating that intravenous administration of 4-PAO may be effective for the reactivation of blocked cholinesterase in the brain. However, the toxicity of 4-PAO (LD(50); 8.89 mg/kg) was greater than that of 2-PAM. Further investigation is required to determine the effects of these alkylPAMs in organophosphate poisoning.
authors.affiliation: Section of Forensic Medicine, Department of International Health Development, Division of Public Health, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan.
authors.forename: Sou
authors.initials: S
authors.lastname: Okuno
authors.forename: Koichi
authors.initials: K
authors.lastname: Sakurada
authors.forename: Hikoto
authors.initials: H
authors.lastname: Ohta
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ikegaya
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kazui
authors.forename: Tomoko
authors.initials: T
authors.lastname: Akutsu
authors.forename: Takehiko
authors.initials: T
authors.lastname: Takatori
authors.forename: Kimiharu
authors.initials: K
authors.lastname: Iwadate
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier; D001921:Brain / Q000378:metabolism*; D002138:Calibration; D002853:Chromatography, Liquid / Q000379:methods*; D003342:Corpus Striatum / Q000196:embryology; D045604:Extracellular Fluid / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D011220:Pralidoxime Compounds / Q000493:pharmacokinetics* / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D011220:Pralidoxime Compounds