1-PENTYL-3-(4-AMINOPHENYL)PYRROLIDINE-2,5-DIONE, A SELECTIVE AROMATASE INHIBITOR - IN-VIVO STUDIES

1-Pentyl, 1-hexyl and 1-heptyl-3-(4-aminophenyl)pyrrolidine-2,5-dione, potent inhibitors of aromatase, lower oestrogen levels in PMSG-stimul ated female rats in a comparable manner to the inhibitor aminoglutethi mide (AG) used clinically for the treatment of breast cancer. Pharmaco kinetic studies in the rat show t1/2 values for the 1-hexyl compound a nd AG of 1.8 and 5.5 h respectively. In 4 tests for CNS-depressant act ivity the overall order of activity was AG > 1-heptyl = 1-hexyl >> 1-p entyl. The 1-pentyl compound has less tendency than AG to depress whit e cell and platelet counts in mice and overall is the drug candidate f or further studies.