Fadrozole

A potent and selective, orally bioavailable aromatase inhibitor with IC50 of 1.7 nM, 180 times more potent than aminoglutethimide; lowers ovarian estrogen synthesis by gonadotropin-primed, androstenedione treated mice, suppresses hormone-dependent and -independent tumors in vivo.Breast Cancer Approved(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. .\n(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. 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. 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.