ATZ Mechanism of Action

Pharmacotherapeutic group: Enzyme inhibitors. ATC Code: L02B G03.
Pharmacology: Pharmacodynamics: Anastrozole is a potent and highly selective nonsteroidal aromatase inhibitor. In postmenopausal women, oestradiol is produced primarily from the conversion of androstenedione to oestrone through the aromatase enzyme complex in peripheral tissues. Oestrone is subsequently converted to oestradiol. Reducing circulating oestradiol levels has been shown to produce beneficial effects in women with breast cancer.
In postmenopausal women, Anastrozole at a daily dose of 1 mg produced oestradiol suppression of greater than 80% using a highly sensitive assay.
Anastrozole does not possess any progestogenic, androgenic or oestrogenic activity.
Daily doses of Anastrozole up to 10 mg do not have any effect on cortisol or aldosterone secretion, measured before or after standard ACTH challenge testing. Corticoid supplements are therefore not needed.
Pharmacokinetics: The pharmacokinetics parameters of 24 subjects were calculated and results were statistically analyzed to demonstrate bioequivalence in a randomized, 2-period, crossover design study. After oral administration of Anastrozole 1 mg film coated tablets (test product), the mean of the maximum plasma concentration (C_max) (rate of absorption) was 15.47 ng/mL, the median t_max was 1.43 h. The extent of absorption is expressed in Area Under the Curve (AUC)_0-t and AUC_0-inf, the mean values were 575.58 ng.h/mL and 628.47 ng.h/mL respectively. The mean elimination half-life (t_½) of Anastrozole 1 mg film coated tablets was 41.01 h.
The T/R ratios and confidence intervals between test and reference product were as follows: for C_max the T/R ratio was 99.94% (96.01%-104.02%). For AUC_0-t the T/R ratio was 98.57% (95.35%-101.90%). The results of the study showed that the T/R ratios and confidence intervals are within the acceptance range for bioequivalence, therefore it can be concluded that the test product, Anastrozole 1 mg film coated tablets, is bioequivalent with the reference product.