(R)-Fadrozole ((R)-CGS 16949A; FAD286) is a potent nonsteroidal inhibitor. (R)-Fadrozole also inhibits human placental aromatase (pIC 50 = 6.17) and aldosterone biosynthesis. (R)-Fadrozole reverses cardiac fibrosis in spontaneously hypertensive heart failure rats..

The (-)-enantiomer with the S-absolute configuration is responsible for the high aromatase inhibitory activity of (R)-Fadrozole[1].

Administration of (R)-fadrozole and (S)-fadrozole (0.24 and 1.2 mg/kg; daily; oral) consistently lowers plasma aldosterone levels. However, a reduction in the urinary aldosterone excretion rate was solely observed with (S)-fadrozole. Notably, (R)-fadrozole at the same dosages was effective in reducing preexisting left ventricular interstitial fibrosis by 50%, contrasting with canrenoate's 42% reduction. Unlike its isomer, (S)-fadrozole exhibited no antifibrotic effects. This study utilized SHHF rats, implementing a dosage regimen of 0.24 and 1.2 mg/kg administered orally on a daily basis, which led to decreased plasma aldosterone levels and a significant reversal of left ventricular interstitial fibrosis.