The preparation of a carbon-11 labelled analgesic — [N-methyl-11C]meptazinol

✍ Scribed by David R. Turton; Sajinder K. Luthra; Victor W. Pike; Malcolm J. Kensett

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: French
• Weight: 363 KB
• Volume: 24
• Category: Article
• ISSN: 0022-2135
• DOI: 10.1002/jlcr.2580240906

✦ Synopsis

A procedure f o r l a b e l l i n g t h e novel a n a l g e s i c , meptazinol [ ( + ) Imethyl-3-ethyl-3-(~-hydroxyphenyl)tetrahydroazepine~, w i t h t h e p o s i t r o ne m i t t i n g r a d i o n u c l i d e , carbon-11 ( t t = 20.4 min) has been developed i n o r d e r t o permit t h e pharmacokinetics of t h i s a n a l g e s i c t o be s t u d i e d i n man. produced from cyclotron-produced [ Clcarbon d i o x i d e , w i t h normeptazinol i n e t h a n o l a t 100 OC f o r 5 min, e v a p o r a t i o n of any unreacted [ lCjiodomethane, p u r i f i c a t i o n by HPLC and removal of s o l v e n t . Subsequent s o l u b i l i s a t i o n of the r a d i o a c t i v e product i n e t h a n o l p l u s i s o t o n i c s a l i n e and s t e r i l i s a t i o n by f i l t r a t i o n produces a s a f e l yi n j e c t a b l e s o l u t i o n o f [N-methyl-l lC]meptazinol i n 14% radiochernical y i e l d (from cyclotron-produced [ Clcarbon d i o x i d e , decay-corrected) . The s p e c i f i c a c t i v i t y o f t h e product i s up t o 7.4 GBq/Pmol a t t h e end of r a d i o s y n t h e s i s (40 min from t h e end o f r a d i o n u c l i d e p r o d u c t i o n ) . P r e p a r a t i o n s have been shown t o be r a d i o c h e m i c a l l y pure and t o be f r e e of norrneptazinol by a n a l y t i c a l HPLC and TLC. That the r a d i o a c t i v e product is "-methyl-Clmeptazinol h a s been unequivocally demonstrated by coi n c l u s i o n of l k -e n r i c h e d iodomethane i n t h e r a d i o s y n t h e s i s and examination of t h e product by broad-band proton-decoupled F o u r i e r transform I ~C -N M R s p e c t r o s c o p y .