Re-examination of the quality control of FASTlab [¹⁸F]FDG products

Objectives FASTlab has been used for [¹⁸F]FDG production [1-2]. However, the intermittent appearance of a white precipitate in the product vial post synthesis prompted us to re-examine the quality of [¹⁸F]FDG products that included the analysis of Al³⁺ in final products.

Methods [¹⁸F]FDG was synthesized using the FASTlab with phosphate buffer cassettes at both RBWH of Australia and NTUH of Taiwan. At RBWH, the appearance of 12 batches of [¹⁸F]FDG were visually observed at different time points and tested the impact of alumina cartridge for such precipitation. At NTUH, 44 batches of [¹⁸F]FDG products were performed complete QC procedures 24 hrs post synthesis except for the analyses related to radioactivity. The concentration of Al³⁺ in [¹⁸F]FDG products were analyzed using ICP-MS at RBWH and with ICP-OES as well as in-house using test stripes and MColortest^TM Al³⁺ test kit analyses at NTUH, respectively.

Results The precipitates appeared in [¹⁸F]FDG products at RBWH and NTUH 8 and 24 hrs, respectively, after synthesis. Rinsing the alumina cartridge prior to radiosynthesis could not prevent the precipitation to occur and the precipitation probability was varied with different batches of FastLab cassette (43-67 %). The in-house tests results indicated that the residual Al³⁺ was less than 5 ppm. However, some batches of FastLab [¹⁸F]FDG products were found to contain 10-15 ppm of Al³⁺ from ICP-MS or ICP-OES analyses.

Conclusions All pharmacopoeias demand that the final product solution should be clear and particulate-free within the given shelf-life/expiration time, which may extend to 20 hours. In order to avoid the potential QC problems, the FastLab citrate buffer cassettes may be a option for [¹⁸F]FDG. Although the Al³⁺ test was not listed in the [¹⁸F]FDG monographs of USP and EP, it was listed in JP. Thus, the residual Al³⁺ test may need to take into consideration.