Preparation and pharmacokinetic evaluation of iodine-125 labeled alphamethyl-L-tyrosine

Cerebral amino acid metabolism is known to be associated with various psychosomatic disorders. 3-(I-123)iodo-L-alpha methyl tyrosine I-123-L-AMT is an alternative to the PET radiopharmaceutical, C-11-thymidine, for brain SPECT studies. Radioiodination of L-alphamethyl tyrosine using chloramine T as well as iodogen has been standardized using I-125 as the first step towards the development of the SPECT imaging agent (123)-I-L-AMT. Purification of the iodinated product was carried out over Sephadex LH-20 column. A quick and easy purification method using Sep-pak column also has been standardized. Quality control of the I-125-L-AMT was carried out by estimating the radiochemical purity and stability of the product. Biodistribution studies of the product were carried out in mice. Time dependent pharmacokinetic studies and activity distribution pattern in the different parts of the brain were also carried out.