A method for labeling substances with technetium or rhenium

PURPOSE: To form a complex of technetium or rhenium having high stability in a neutral pH range by using a specified large ring complexing agent. CONSTITUTION: The labeling substance (particularly, monoclonal antibody or the fragment) is allowed to react with a compound of formula I [R is NH 2 , N=C=S, formula II, formula III (X is a 1-6C alkylene, 6-12C arylene, 1-6C alk-6-12C arylene)], for example, 1-(p-aminophenyl)-2,5,9,12- tetrazacyclotetradecane, to treat the obtained compound with pertechnetate-99 or -99m or perrhenate-186 or -188 and a reducing agent (preferably a tin (II) compound, particularly complex-stabilized tin (II) salt) in the pH <9, preferablly pH ≥6 to <8, or allowing the compound of formula I to react with an appropriate peroxide compound and a reducing agent, then the obtained complex to react with a labeled substance and to label with Te-99, Tc-99m, Re-186 or Re-188. COPYRIGHT: (C)1993,JPO