Anastrozole
Also known as: Arimidex · AI · Aromatase Inhibitor
A potent aromatase inhibitor that reduces estrogen conversion from testosterone, used to manage estradiol levels during TRT and hormone optimization.
Overview
Anastrozole is a non-steroidal aromatase inhibitor that blocks the enzyme aromatase (CYP19A1), which converts androgens (testosterone, androstenedione) into estrogens (estradiol, estrone). Originally developed for the treatment of estrogen receptor-positive breast cancer in postmenopausal women, it has become widely used in men's health to manage estradiol levels during testosterone replacement therapy. During TRT, increased testosterone levels lead to proportionally increased aromatization and estradiol production. While estradiol is essential for men's health (bone density, libido, cardiovascular protection, neuroprotection), excessive levels can cause gynecomastia, water retention, mood disturbances, and sexual dysfunction. Anastrozole allows precise management of the testosterone-to-estradiol ratio.
Modern practice has shifted toward using the lowest effective dose, as over-suppression of estradiol causes its own set of problems including joint pain, low libido, depression, and bone loss. Many practitioners now target estradiol levels of 20-35 pg/mL rather than aiming for the lowest possible level.
Mechanism of Action
Competitively binds to the heme group of aromatase (CYP19A1), reversibly inhibiting the conversion of androgens to estrogens. Reduces circulating estradiol by approximately 70-85% at standard doses. Does not affect adrenal corticosteroid or aldosterone synthesis. Selectivity for aromatase over other CYP enzymes is high.
Key Benefits
Potential Side Effects
Common Stacks
This peptide is commonly combined with the following compounds for synergistic effects:
Known Interactions
The following interactions have been documented for Anastrozole. Always consult a healthcare professional before combining compounds.
Contraindicated (1)
Anastrozole blocks estrogen production. Using it alongside estrogen replacement therapy is counterproductive — it would negate the estrogen being administered.
Synergistic (1)
Anastrozole blocks aromatase to prevent testosterone from converting to estrogen. Used to manage estrogen levels during TRT and prevent gynecomastia.
Scientific References
Quick Reference
Typical Dose
0.25-0.5 mg, 2-3 times per week (with TRT); highly individual
Frequency
2-3 times per week; dose titrated based on bloodwork
Route
Oral tablet
Half-Life
~46.8 hours
Cycle Length
Ongoing alongside TRT; estradiol monitored every 6-12 weeks
FDA Status
FDA approved (Arimidex) for breast cancer; off-label for estrogen management in men
Need to calculate dosing?
Use our reconstitution calculator to determine exact syringe measurements.
Open CalculatorThis information is for educational purposes only. Consult a qualified healthcare professional before using any peptide. Dosing information reflects commonly reported protocols and may not be appropriate for everyone.
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