PET study of the distribution of [11C]fluoxetine in a monkey brain

No-carrier-added [11C]fluoxetine (2) was synthesized by methylation of norfluoxetine (1) with [11C]H3I in 20% radiochemical yield in a synthesis time of 40 min from EOB with a specific activity of 0.48 Ci/microM (EOB). In vivo study in mouse indicated that the uptake of 2 in mouse tissues was high and the radioactivity remained constant throughout the study. The uptake of 2 in mouse brain was 4%/g. PET study in a Rhesus monkey also showed that the uptakes of 2 in different brain regions were similar and the retention of radioactivity in these regions remained constant throughout the study (80 min). Analysis of arterial plasma by HPLC showed that only 20% of radioactivity in the plasma remained as 2 at 30 min post-injection. These results suggest that the uptake of fluoxetine in monkey brain is probably not receptor mediated. Rather, blood flow, lipophilicity or other transport mechanisms may play a role in its uptake.