Anastrozole vs Arimistane

Mechanism

Anastrozole is a potent, selective, non-steroidal third-generation aromatase inhibitor that competitively binds the heme group of cytochrome P450 aromatase (CYP19A1), blocking the conversion of testosterone to estradiol and androstenedione to estrone. In men on TRT, this reduces circulating estradiol by 50-80%, shifting the testosterone-to-estradiol ratio favorably. Estrogen suppression releases hypothalamic negative feedback, increasing GnRH, LH, and FSH secretion in non-TRT contexts. Complete estrogen ablation is detrimental to bone density, lipid metabolism, and cognitive function.

Standard Dosing

Research indicates 0.25-0.5 mg twice weekly as a TRT adjunct for estrogen management. Stand-alone hypogonadism: 1 mg twice weekly.

Timing

Take on testosterone injection days or the day after when aromatization peaks. Consistent schedule for stable estradiol control.

Cycle Duration

Ongoing as needed alongside TRT. Reassess every 3-6 months with estradiol labs. Goal is minimal effective dose.

Side Effects

• Joint pain and stiffness (from excessive estrogen suppression)
• Bone density loss with chronic use
• Lipid profile worsening (HDL suppression)
• Fatigue and brain fog (from over-suppression of estradiol)
• Mood disturbances and depression
• Hot flashes
• Decreased libido (if estradiol drops below ~15 pg/mL)

Contraindications

• Premenopausal women
• Known hypersensitivity to anastrozole
• Pre-existing severe osteoporosis (estrogen suppression worsens bone loss)
• Children (may affect bone growth plate closure)

Best Stacking Partners

Mechanism

Suicidal aromatase-modulating compound marketed to reduce estrogen conversion, though evidence quality and product purity vary.

Contraindications

• Do not use without estradiol monitoring