Background: The SR101 N-(3-[18F]Fluoropropyl) sulfonamide ([18F]SRF101) is a Sulforhodamine
101 derivative that was previously synthesised by our group. The fluorescent dye SR101
has been reported as a marker of astroglia in the neocortex of rodents in vivo.
Objective: The aim of this study was to perform a toxicological evaluation of [18F]SRF101 and to estimate
human radiation dosimetry based on preclinical studies.
Methods: Radiation dosimetry studies were conducted based on biokinetic data obtained from a mouse
model. A single-dose toxicity study was carried out. The toxicological limit chosen was <100 μg, and
allometric scaling with a safety factor of 100 for unlabelled SRF101 was selected.
Results: The absorbed and effective dose estimated using OLINDA/EXM V2.0 for male and female
dosimetric models presented the same tendency. The highest total absorbed dose values were for different
sections of the intestines. The mean effective dose was 4.03 x10-3 mSv/MBq and 5.08 x10-3
mSv/MBq for the male and female dosimetric models, respectively, using tissue-weighting factors
The toxicity study detected no changes in the organ or whole-body weight, food consumption, haematologic
or clinical chemistry parameters. Moreover, lesions or abnormalities were not found during the
Conclusion: The toxicological evaluation of SRF101 verified the biosafety of the radiotracer for human
administration. The dosimetry calculations revealed that the radiation-associated risk of
[18F]SRF101 would be of the same order as other 18F radiopharmaceuticals used in clinical applications.
These study findings confirm that the novel radiotracer would be safe for use in human PET