Recent publications reported high uptake of the carbon-11 labelled 11β-hydroxylase inhibitors (R)–[O–methyl-11C]metomidate ([11C]MTO) and (R)–[O–ethyl-11C]etomidate ([11C]ETO) in adrenocortical incidentalomas with excellent selectivity for positron emission tomography (PET). In our studies [18F]FETO, (the [18F]fluoroethyl ester of etomidate, (R)-1-(1-phenylethyl)-1H-imidazole-5-carboxylic acid, 2′-[18F]fluoroethyl ester), an analogue of [11C]MTO and [11C]ETO was chosen due to the suspected similarity of the pharmacokinetic and pharmacodynamic properties, and was prepared in the following two step procedure: First, [18F]fluoride was reacted with 2-bromoethyl triflate using the kryptofix/acetonitrile method to yield 2–bromo-[18F]fluoroethane ([18F]BFE). In the second step, [18F]BFE was reacted with the tetrabutylammonium salt of (R)-1-(1-phenylethyl)-1H-imidazole-5-carboxylic acid to yield [18F]FETO, a novel inhibitor of the 11β-hydroxylase. The proposed synthesis of [18F]FETO allows the production of sufficient amounts of this new PET-tracer to serve 1–2 patients with an overall synthesis time of less than 80 min. Copyright © 2003 John Wiley & Sons, Ltd.
最近发表的研究报告称,肾上腺皮质偶发瘤对碳-11标记的11β-羟化酶
抑制剂(R)-[O-甲基-11C]甲巯咪idate([11C]
MTO)和(R)-[O-乙基-11C]依托咪idate([11C]ETO)具有很高的吸收率,且正电子发射断层扫描(PET)选择性极佳。在我们的研究中,[18F]FETO(
依托咪酯的[18F]
氟乙酯,(R)-1-(1-苯基乙基)-1H-咪
唑-5-羧酸,2′-[18F]
氟乙酯)是[11C]
MTO 和[11C]ETO 的类似物,由于药代动力学和药效学特性疑似相似而被选中,其制备过程分为以下两步:首先,采用
氪/
乙腈法使[18F]
氟化物与三
氟溴乙烷反应,生成 2-
溴-[18F]
氟乙烷([18F]BFE)。第二步,[18F]BFE 与 (R)-1-(1-phenylethyl)-1H-imidazole-5-carboxylic acid 的
四丁基铵盐反应,得到 [18F]FETO,一种新型的 11β- 羟化酶
抑制剂。拟议的[18F]FETO 合成方法可生产出足够数量的这种新型 PET 示踪剂,供 1-2 名患者使用,整个合成时间不到 80 分钟。Copyright © 2003 John Wiley & Sons, Ltd. All Rights Reserved.