ORG 33201 - A NEW HIGHLY SELECTIVE ORALLY ACTIVE AROMATASE INHIBITOR

Org 33201 has been selected as a very potent aromatase inhibitor. The compound is an enantiomer of a SC2H5 substituted imidazoylethylphenale ne. Org 33201 inhibited human aromatase activity for 50% at a concentr ation of 2.2 x 10(9) mol/l. More than 200-fold higher concentrations w ere needed for the inhibition of other cytochrome P450 enzymes. In viv o the compound was active in rats (ED50 = 0.035 mg/kg) and dogs (1 mg/ kg gave 70% inhibition) after oral administration. It can be concluded that Org 33201 is a potent and highly selective orally active aromata se inhibitor.