[18F]1 was prepared via direct 18F-fluorination by heating the corresponding tosylated derivative (3) with [18F]fluoride as its Kryptofix 222 complex in dimethyl sulfoxide at 110 °C for 15 min, following by HPLC purification. Non-clinical safety tests were performed for the extended single-dose toxicity study in rats, and for the in vitro metabolite analysis with human liver microsomal incubation.
High quality batches of [18F]1, compatible with clinical applications, were obtained. At the end of irradiation, the decay-corrected radiochemical yield of [18F]1 using 1 and 5 mg of precursor based on [18F]fluoride was 18.5 ± 7.9% (n = 10) and 52.0 ± 5.8% (n = 3), respectively. A single-dose of [18F]1 did not show toxicological effects for 14 days after the injection in male and female rats. In human liver microsomal incubations, [18F]1 was easily metabolized to [18F]desbenzyl-FEDAC ([18F]10) by CYPs (4.2% of parent compound left 60 min after incubation).
We successfully synthesized clinical grade batches of [18F]1 and verified the absence of innocuity of this radiotracer. [18F]1 will be used to first-in-human studies in our facility.