Optimizing an online SPE-HPLC method for analysis of (R)-[11C]1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarb oxamide [(R)-[11C]PK11195] and its metabolites in humans

Henri N.J.M. Greuter, Patricia L.B. Van Ophemert, Gert Luurtsema, Bart N.M. Van Berckel, Eric J.F. Franssen, Bert D. Windhorst, Adriaan A. Lammertsma

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(R)-[11C]PK11195 is used as a positron emission tomography tracer for activated microglia in several neurological disorders. Quantification of specific binding requires a metabolite-corrected plasma input function. In this study, a high-performance liquid chromatography (HPLC) procedure with online solid phase extraction was modified for analyzing (R)-[ 11C]PK11195 plasma samples, yielding total sample recoveries of more than 98%. When applied to human studies, the use of two HPLC systems enabled analysis of up to seven plasma samples under regular conditions. Online radioactivity detection was compared with offline sample measurements of HPLC profiles. Offline measurements provided the most reliable results especially for late plasma samples. In 10 patients, an average decrease of parent compound from 94.6% at 2.5 min to 45.2% at 1 h after administration was observed.

Original languageEnglish
Pages (from-to)307-312
Number of pages6
JournalNuclear medicine and biology
Issue number3
Publication statusPublished - 1 Jan 2005


  • (R)-[ C]PK11195
  • Benzodiazepine receptor
  • HPLC
  • Metabolism
  • Positron emission tomography

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