Description
Anastrozole (Arimidex) is a non-steroidal, reversible third-generation aromatase inhibitor. Structurally the substance is a triazole derivative that binds competitively to the active site of the aromatase enzyme (CYP19A1) and prevents the conversion of androgens to estrogens.
Per study reports Anastrozole lowers circulating estradiol levels by 70-85% with daily dosing. The effect onsets quickly (steady-state within 7 days) and is equally quickly reversible after discontinuation - typical of reversible AIs.
In anabolic research Anastrozole is used to control aromatization of supraphysiologic testosterone doses. High test levels lead to increased aromatase activity and thus E2 spikes associated with water retention, mood swings, hypertension, and gynecomastia research findings. Anastrozole curbs this conversion specifically.
The fine dose-response curve makes Anastrozole a precise tool: 0.25-0.5mg every 2-3 days suffices in many research protocols to keep E2 in the physiologic range. Unlike Exemestane, Anastrozole is reversible - this enables cycle adjustments without long recovery times.
Pharmacokinetically orally bioavailable with about 50-hour half-life. Known effects in studies: at too-strong E2 suppression (E2 under 20 pg/ml), joint pain, low libido, and mood depression appear. Estradiol monitoring (blood tests) in longer research protocols is therefore important.
You can order Anastrozole as oral tablets in one bottle with 1mg per tablet.
This information is for research and educational purposes only. No medical recommendations.
Risks & Safety
Anastrozole sits in the mid range of the risk scale. As a reversible aromatase inhibitor the central risk lies not in the compound itself but in lowering estradiol too far.
Documented in studies and the literature:
- Estradiol crash: at E2 below about 20 pg/ml, joint pain, low libido and low mood are documented - the lead problem of all aromatase inhibitors.
- Lipid profile: the estrogen lowering can unfavorably affect the lipid profile in the literature.
- Bone density: sustained low estradiol is associated with bone density loss.
- Steep dose curve: the steep dose-response curve makes accidental over-dosing easy, so estradiol monitoring is recommended in the literature.
Monitoring via bloodwork is recommended. This classification does not replace medical advice. Risk and responsibility for any actual use lie entirely with the buyer.
Studies
- Anastrozole Versus Tamoxifen as First-Line Therapy for Advanced Breast Cancer in 668 Postmenopausal Women - Journal of Clinical Oncology 2000, Bonneterre et al: Classic approval study on efficacy and tolerability of Anastrozole.
- Effects of aromatase inhibition in hypogonadal older men: a randomized, double-blind, placebo-controlled trial - Clinical Endocrinology 2008, Burnett-Bowie et al: Randomized study on the Anastrozole effect on testosterone and estradiol in men.
- Gonadal Steroids and Body Composition, Strength, and Sexual Function in Men - New England Journal of Medicine 2013, Finkelstein et al: Landmark study that uses aromatase inhibition to disentangle the separate roles of testosterone and estradiol in men.
- Effects of aromatase inhibition vs. testosterone in older men with low testosterone: randomized-controlled trial - Andrology 2015, Dias et al: Direct comparison of aromatase inhibition and testosterone administration at low testosterone.
- Effect of anastrozole and tamoxifen as adjuvant treatment for early-stage breast cancer: 10-year analysis of the ATAC trial - The Lancet Oncology 2010, Cuzick et al: Long-term safety data over ten years.
