D inhibitor [18F]PF-9811 (4-(3-((5-(2[18F]fluoroethoxy)pyridine-2-yl)oxy)benzylidene)-N-(pyridazin-3-yl)piperidine-1carboxamide) [27] which is an analogue of PF-04457845. [18F]PF-9811 demonstrated modest brain uptake (0.8 SUV in the cortex at 90 min) and distinct to non-specific binding ratios (2.3 ?two.6) in rodents. A reversible radiotracer for FAAH, [11C]MK-3168 ((1S,2S)-2(4-(5-((5-chloropyridin-2-yl)thio)-1-[11C]methyl-1H-imidazol-4-yl)phenyl)-N,Ndimethylcyclopropanecarboxamide), was lately reported in abstract type [28, 29]. Pursuant to our efforts to create FAAH radiotracers for PET in vivo imaging studies, we identified PF-04457845 as a potential candidate on account of its favorable pharmacokinetic properties (high bioavailability and brain penetration), high selectivity, and identified security in humans [30, 31]. To circumvent modifications for the structure of PF-04457845, we elected to prepare the carbon-11 isotopologue by radiolabeling in the urea carbonyl by means of [11C]CO2 fixation. Herein we report the radiosynthesis of [11C-carbonyl]PF-04457845 ([11C]PF-04457845, Scheme 1) as well as the ex vivo brain biodistribution and blocking research in conscious rodents.2,6-Di(1-pyrazolyl)pyridine site NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptNucl Med Biol. Author manuscript; accessible in PMC 2014 August 01.Hicks et al.Page2. Methods2.1 Common supplies and methodsNIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptAll reagents were utilized as bought from Sigma Aldrich. Solvents utilized were either reagent or HPLC grade and purchased from Caledon Laboratories or Sigma Aldrich. A Scanditronix MC 17 cyclotron was applied for radionuclide production. [11C]CO2, developed by the 14N(p,)11C nuclear reaction, was concentrated from the gas target in a stainless steel coil cooled to -178 . Upon warming, the [11C]CO2 in a stream of N2 gas was passed through a NOx trapping column along with a drying column of P2O5 before use [32]. Purifications and analyses of radioactive mixtures were performed by high performance liquid chromatography (HPLC) with an in-line UV detector (254 nm) in series using a NaI crystal radioactivity detector. Isolated radiochemical yields were determined with a dose calibrator (Capintec CRC-712M). Automated radiosyntheses were controlled by LabviewTM software. Unless otherwise stated, all radioactivity measurements have been corrected for radioactive decay. POCl3 was distilled below reduced stress before use. All animal experiments have been carried out under humane conditions, with approval from the Animal Care Committee at the Centre for Addiction and Mental Overall health and in accordance with all the recommendations set forth by the Canadian Council on Animal Care.Tributyl(1-ethoxyethenyl)stannane structure Rats (male, Sprague Dawley) have been kept on a reversed 12 h light/12 h dark cycle and allowed meals and water ad libitum.PMID:27641997 The radiolabeling precursor, 2-(3-piperidin-4-ylidenemethyl-phenoxy)-5-trifluoromethyl-pyridine hydrochloride (PPP) and the authenticated normal (PF-04457845) have been prepared via a literature process [16]. [11C]CURB was prepared via the literature process [20]. 2.2 Radiosynthesis of [11C]PF-04457845 Carbon-11 labeled CO2 was dispensed within a stream of nitrogen (7 mL/min) into a 1 mL conical vial charged with phosphazene base BEMP (2-tert-butylimino-2-diethylamino-1,3dimethylperhydro-1,three,2-diazaphosphorine; six.92 mol) and PPP (2.70 mol) in anhydrous CH3CN (100 L) as well as three minopyridazine (3-APZ, 52.six mol) in anhydrous 1:1 CH3CN:DMSO (one hundred L). One min soon after radioactiv.
