Nucl Med Mol Imaging.  2009 Aug;43(4):337-343.

A Convenient Radiolabeling of [11C](R)-PK11195 Using Loop Method in Automatic Synthesis Module

• Lee HJ
• Jeong JM
• Lee YS
• Kim HW
• Choi JY
• Lee DS
• Chung JK
• Lee MC

Abstract

PURPOSE: ((R)-1-(2-chlorophenyl)-N-1-[11C]methyl-N-(1-propyl)-3-isoquinoline carboxamide ((R)-PK11195) is a specific ligand for the peripheral type benzodiazepine receptor and a marker of activated microglia, used to measure inflammation in neurologic disorders. We report here that a direct and simple radiosynthesis of [11C](R)-PK11195 inmild condition using NaH suspension in DMF and one-step loop method.
MATERIALS AND METHODS
(R)-NDesmethyl- PK11195 (1 mg) in DMSO (0.1 mL) and NaH suspension in DMF (0.1 mL) were injected into a semi-prep HPLC loop. [11C]methyl iodide was passed through HPLC loop at room temperature. Purification was performed using semi-preparative HPLC. Aliquots eluted at 11.3 min were collected and analyzed by analytical HPLC and mass spectrometer.
RESULTS
The labeling efficiency of [11C](R)-PK11195 was 71.8+/-8.5%. The specific activity was 11.8 +/-6.4 GBq/micromol and radiochemical purity was higher than 99.2%. The mass spectrum of the product eluted at 11.3 min showed m/z peaks at 353.1 (M+1), indicating the mass and structure of (R)-PK11195.
CONCLUSION
By the one-step loop method with the [11C]CH3I automated synthesis module, [11C](R)-PK11195 could be easily prepared in high radiochemical yield using NaH suspension in DMF.

Keyword

PK11195; microglia; PBR; PET; [11C]methyl iodide; loop method

MeSH Terms

Chromatography, High Pressure Liquid
Dimethyl Sulfoxide
Inflammation
Isoquinolines
Microglia
Nervous System Diseases
Receptors, GABA-A
Dimethyl Sulfoxide
Isoquinolines
Receptors, GABA-A