Labeling peptides with rhenium-188

A direct labeling technique via EHDP for the preparation of Re-188-somatost atin analogue peptide beta-(2-naphthyl)D-Ala-Cys-Tyr-D-Trp-Lys-Val-Cys-Thr- amide complex was developed. The influence of reaction conditions such as p H, temperature, weak ligand concentration and stannous chloride concentrati on were investigated. Methods of analysis were also established permitting identification of radiochemical impurities which may be present in the radi opharmaceutical solution. Results showed that under the procedure reported herein Re-188-peptide complex can be prepared with a radiochemical purity o f 90% and a specific activity up to 1.8 GBq mg(-1) without radiolytic degra dation of the product. (C) 1999 Elsevier Science B.V. All rights reserved.