Fadrozole

Fadrozole (CGS 16949A free base) is a potent, selective and nonsteroidal inhibitor of aromatase with an IC₅₀ of 6.4 nM. IC50 & Target:IC50: 6.4 nM (aromatase)^[1] In Vitro: Fadrozole hydrochloride is a very potent inhibitor of both human placental and rat ovarian aromatase. In hamster ovarian slices, fadrozole hydrochloride inhibits the production of estrogen with an IC₅₀ of 0.03 μM. The production of progesterone is inhibited with an IC₅₀ of 120 μM. Synthesis of other cytochrome P-450 dependent steroids can be suppressed to various degrees with higher doses of fadrozole hydrochloride. ^[1]. In Vivo: Fadrozole hydrochloride is able to inhibit the aromatase-mediated androstenedione-induced uterine hypertrophy in immature female rats with an ED₅₀ of 0.03 mg/kg when given orally. In the same model, aminoglutethimide elicits the same effect with an ED₅₀ of 30 mg/kg when given orally^[1]. Fadrozole hydrochloride prevents the development of both benign and malignant spontaneus mammary neoplasns in female Sprague-Dawley rats. It also slows the spontaneous development of ptuitary pars dta mas in female rats, and reduces the of spontaneous hcu ar tumours in male and female rats^[2]. Administration of fadrozole in male and female mice suppresses the production of 17b-estradiol, accompanied with a 70% reduction in parasite burden. This protective effect is associated in male mice with a recovery of the specific cellular immune response. Interleukin-6 (IL-6) serum levels, and its production by splenocytes, is augmented by 80%, together with a 10-fold increase in its expression in testes of infected male mice. Fadrozole treatment returns these levels to baseline values^[3].