5-(4-(2-[18F]fluoroethoxy)phenyl)-1-(2,4-dichlorophenyl)-4-cyano-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide ([18F]JHU88868), a Novel radioligand for PET imaging of cannabinoid type 1 receptors

Yongjun Gao, Hayden T. Ravert, Robert F. Dannals, Andrew G. Horti

Research output: Contribution to journalArticlepeer-review


PET imaging of cannabinoid type 1 receptor (CB1) is important for assessment of the receptor role in many neurological and psychiatric disorders. 5-(4-(2-[18F]fluoroethoxy)phenyl)-1-(2,4-dichlorophenyl)-4-cyano-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide ([18F]JHU88868), an analog of the radiotracer of choice for PET imaging of CB1 receptors in humans [11C]JHU75528 ([11C]OMAR), with a longer half-life exhibits high CB1 binding affinity (Ki = 16, 17 nM) and moderate lipophilicity. An efficient synthesis of JHU88868 and its bromoethoxy derivative for radiolabeling are presented. [18F]-2 ([18F]JHU88868) was prepared in one step by a Kryptofix-assisted radiofluorination of the corresponding bromo-precursor in DMSO solution at 135°C using a nucleophilic fluorination radiochemistry box with radiochemical yield of 1-5%, radiochemical purity greater than 95% and the average specific activity of 4000 mCi/ mol at the end-of-synthesis.

Original languageEnglish (US)
Pages (from-to)195-198
Number of pages4
JournalCurrent Radiopharmaceuticals
Issue number3
StatePublished - 2009


  • Cannabinoid receptor
  • Positron emission tomography (PET)
  • Radiofluorination

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging
  • Pharmacology


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