Chemical aspects of labeling sucralfate with 99mTcO4

Two formulations of [99mTc]sucralfate have been used to image gastric and duodenal ulcers and inflammatory bowel disease. One formulation is a complexation of [99mTc]HSA with sucralfate. The second is prepared by directly labeling sucralfate with [99mTc]pertechnetate in the presence of stannous ion. An in vitro study of the factors affecting the production and stability of these labeled sucralfate preparations was conducted. Both formulations were stable at the acidic pH likely encountered in the stomach. However, at pH greater than 6 the albumin-sucralfate complex began to dissociate while directly labeled sucralfate was stable to a pH of 9. Conversely it was shown that directly labeled sucralfate was more susceptible to loss of 99mTc to other chelating species. Sucralfate complexed with [99mTc]HSA was radiochemically stable up to a specific activity of 26 GBq (700 mCi) per gram while directly labeled sucralfate showed decreased 24-hr stability at specific activities greater than 837 mCi (31 GBq) per gram.