An improved preparation of [18F]AV ‐45 by simplified solid‐phase extraction purification

Amyvid (florbetapir f18, [18F]AV ‐45, [18F]5) was the first FDA approved positron emission tomography (PET) imaging agent targeting β‐amyloid (Aβ) plaques for assisting the diagnosis of Alzheimer's disease. This work aimed to improve the [18F]AV ‐45 ([18F]5) preparation by using solid ‐phase extraction (SPE) purification. [18F]AV ‐45 ([18F]5) was synthesized by direct nucleophilic radiofluorination ofO‐tosylated precursor (1 mg) at 120 °C in anhydrous dimethyl sulfoxide (DMSO), followed by acid hydrolysis of theN‐Boc protecting group. Purification was accomplished by loading the crude reaction mixture to a cartridge (Oasis HLB 3 cc) and eluting with different combinations of solvents. This method removed the chemical impurity while leaving [18F]AV ‐45 ([18F]5) on the cartridge. The final dose was eluted by ethanol. [18F]AV ‐45 ([18F]5) was produced within 51 min (radiochemical yield 42.7 ± 5.9%, decay corrected, n = 3), and the radiochemical purity was>95%. Total chemical impurity per batch (24.1 ± 2.7 μg per batch) was below the limit described in the package insert of Amyvid, florbetapir f18 (chemical mass: less than 50 μg/dose). In summary, [18F]AV ‐45 ([18F]5) was produced efficiently and reproducibly using a cartridge ‐based SPE purification. This method brings the process closer for routine preparation, similar to the commercially used [18F]FDG.
Source: Journal of Labelled Compounds and Radiopharmaceuticals - Category: Biochemistry Authors: Tags: RESEARCH ARTICLE Source Type: research