RESUMO
A radioiodinated derivative of the anorexinergic drug phentermine was synthesized and evaluated as a potential brain imaging agent. Stoichiometric iodination of the intermediate 4-aminophentermine (AmP) gave a mixture of mono and diiodo products, while the radioiodination at the no-carrier-added (NCA) level gave 73% isolated yield of the 3-[125I]iodo-4-aminophentermine with less than 2% of the diiodo derivative. The tissue distribution of the radiochemical in rats showed that it was readily extracted by the brain followed by relatively slow clearance from that organ. However, a comparison with other labeled phentermine derivatives indicated that the total brain uptake, retention and selectivity of the new agent were poorer, probably as a result of the presence of the 4-amino substituent.
Assuntos
Encéfalo/diagnóstico por imagem , Radioisótopos do Iodo , Fentermina/análogos & derivados , Animais , Barreira Hematoencefálica , Fenômenos Químicos , Química , Feminino , Indicadores e Reagentes , Cinética , Masculino , Perfusão , Fentermina/síntese química , Cintilografia , Ratos , Ratos Endogâmicos , Relação Estrutura-Atividade , Distribuição TecidualRESUMO
The inhibitory potencies of a series of N-substituted phentermines on the synaptosomal uptake of l-norepinephrine were found to be similar to those of the corresponding amphetamines. Quaternization of N, N-dimenthyl-d-amphetamine diminished, but did not abolish, its inhibitory potency, indicating that a permanently charged cation is also effective. Since the addition of an aromatic moiety at the end of a four-atom chain originating at the nitrogen of amphetamine or phentermine significantly increased inhibitor strength, several 3-aryloxypropylamines and 4-phenylbutylamine were tested, but they were much weaker inhibitors than dl-amphetamine. Thus, the observed increase in inhibitor potency apparently was not simply the result of a specific interaction of the "nonmimic" portion of the N-substituted amphetamines or phentermines.
