The present invention is related to neurotensin receptor antagonists of formula (I):whereinR1 is selected from the group consisting of hydrogen, methyl and cyclopropylmethylAA-COOH is an amino acid selected from the group consisting of 2-amino-2-adamantane carboxylic acid, cyclohexylglycine and 9-amino-bicyclo[3.3.1]nonane-9-carboxylic acidR2 is selected from the group consisting of (C1-C6)alkyl, (C3-C8)cycloalkyl, (C3-C8)cycloalkylmethyl, halogen, nitro and trifluoromethylALK is (C2-C5)alkylideneR3, R4 and R5 are each and independently selected from the group consisting of hydrogen and (C1-C4)alkyl under the proviso that one of R3, R4 and R5 is of the following formula (II)whereinALK is (C2-C5)alkylideneR6 is selected from the group consisting of hydrogen and (C1-C4)alkyl andR7 is selected from the group comprising H, Acceptor, -[Acceptor-Effector], -[Linker-Acceptor], and -[Linker-Acceptor-Effector], whereinAcceptor is a moiety which mediates linking of an Effector to the N atom of formula (II) or which mediates linking of the Effector to the Linker,Effector is selected from the group comprising a diagnostically active agent and a therapeutically active agent,Linker is a moiety which links the Acceptor to the N atom of formula (II),-[Acceptor-Effector] is a moiety where the Effector is complexed or covalently bound to the Acceptor,-[Linker-Acceptor] is a moiety where the Linker is conjugated to the Acceptor, and-[Linker-Acceptor-Effector] is a moiety where the Linker is conjugated to the Acceptor, whereby the Effector is complexed or covalently bound to the Acceptoror a pharmacologically acceptable salt, solvate or hydrate thereof.
