1067642-12-9Relevant academic research and scientific papers
Synthesis and evaluation of [N-methyl-11C]N-desmethyl-loperamide as a new and improved PET radiotracer for imaging P-gp function
Lazarova, Neva,Zoghbi, Sami S.,Hong, Jinsoo,Seneca, Nicholas,Tuan, Ed,Gladding, Robert L.,Liow, Jeih-San,Taku, Andrew,Innis, Robert B.,Pike, Victor W.
, p. 6034 - 6043 (2008)
[11C]Loperamide has been proposed for imaging P-glycoprotein (P-gp) function with positron emission tomography (PET), but its metabolism to [N-methyl-11C]N-desmethyl-loperamide ([11C]dLop; [ 11C]3) precludes quantification. We considered that [11C]3 might itself be a superior radiotracer for imaging brain P-gp function and therefore aimed to prepare [11C]3 and characterize its efficacy. An amide precursor (2) was synthesized and methylated with [11C] iodomethane to give [11C]3. After administration of [11C]3 to wild-type mice, brain radioactivity uptake was very low. In P-gp (mdr-1a(-/-)) knockout mice, brain uptake of radioactivity at 30 min increased about 3.5-fold by PET measures, and over 7-fold by ex vivo measures. In knockout mice, brain radioactivity was predominantly (90%) unchanged radiotracer. In monkey PET experiments, brain radioactivity uptake was also very low but after P-gp blockade increased more than 7-fold. [11C]3 is an effective new radiotracer for imaging brain P-gp function and, in favor of future successful quantification, appears free of extensive brain-penetrant radiometabolites.
A high-yield route to synthesize the P-glycoprotein radioligand [ 11C]N-desmethyl-loperamide and its parent radioligand [ 11C]loperamide
Wang, Min,Gao, Mingzhang,Zheng, Qi-Huang
, p. 5259 - 5263 (2013/09/23)
N-Desmethyl-loperamide and loperamide were synthesized from α,α-diphenyl-γ-butyrolactone and 4-(4-chlorophenyl)-4- hydroxypiperidine in five and four steps with 8% and 16% overall yield, respectively. The amide precursor was synthesized from 4-bromo-2,2- diphenylbutyronitrile and 4-(4-chlorophenyl)-4-hydroxypiperidine in 2 steps with 21-57% overall yield. [11C]N-Desmethyl-loperamide and [ 11C]loperamide were prepared from their corresponding amide precursor and N-desmethyl-loperamide with [11C]CH3OTf through N-[11C]methylation and isolated by HPLC combined with solid-phase extraction (SPE) in 20-30% and 10-15% radiochemical yields, respectively, based on [11C]CO2 and decay corrected to end of bombardment (EOB), with 370-740 GBq/μmol specific activity at EOB.
