Triazole-based reversible competitive aromatase (CYP19) inhibitor. Blocks peripheral conversion of androgens (testosterone, androstenedione) to estrogens (estradiol, estrone) — the dominant estrogen source in postmenopausal women. >96% aromatase inhibition + >80% estradiol suppression at 1 mg/d. No effect on adrenal steroidogenesis at therapeutic doses (distinguishes from older steroidal AIs like aminoglutethimide). Also used off-label in men on TRT or AAS to control aromatisation-driven gynaecomastia.
Half-Life (t½)
PO: 50h
Dosing Guidelines
PO: Typical 0.5 mg (Range: 0.25–1 mg)
Target Organ Systems
endocrine
digestive
reproductive
Interactions
Tamoxifen (caution): Co-administration reduces anastrozole AUC ~27%. Class-switch rather than combine.
Testosterone (TRT) (synergistic): Off-label pairing to limit E2 rise from exogenous T. Over-suppression of E2 causes its own bone + CV issues — target mid-range, not floor.