Exemestane
Also known as: Aromasin
A steroidal (irreversible) aromatase inhibitor used off-label as an alternative to anastrozole for controlling estrogen on testosterone therapy. Prescription medication (approved for breast cancer).
Last updated
Mechanism of Action
Exemestane is a steroidal 'suicide' aromatase inhibitor: it binds aromatase irreversibly and permanently inactivates the enzyme, lowering the conversion of testosterone to estradiol. Because the enzyme must be regenerated, it avoids some of the rebound seen with reversible inhibitors. As with any aromatase inhibitor, some estradiol is essential for male health, so over-suppression is harmful and dosing is conservative and lab-guided.
- Half-life
- ~24 hours (enzyme effect lasts longer due to irreversible binding)
- Administration Routes
- Oral
- Research Status
- Clinical
Reported Benefits
- Lowers elevated estradiol on testosterone therapy
- Irreversible action avoids the estrogen rebound of reversible AIs
- Generally neutral effect on lipids at low doses
Potential Side Effects
- Over-suppression of estradiol (joint pain, low libido, mood changes)
- Reduced bone mineral density with excessive use
- Fatigue
Common Dosing
When used, protocols report low doses a few times weekly, titrated to estradiol labs. Many men on well-managed TRT need no aromatase inhibitor. Physician-directed only.
The dosing information above is aggregated from research literature and anecdotal community reports for educational purposes only. It is not a recommendation, prescription, or medical advice. Peptides are sold as research chemicals only and are not intended for human use.
Contraindications
- Women who are or may become pregnant
- Osteoporosis / low bone density (relative)
- Do not drive estradiol below the healthy male range
Testosterone Cypionate
A long-acting injectable testosterone ester used clinically for testosterone replacement therapy (TRT) in men with diagnosed hypogonadism. Prescription medication.
Testosterone Enanthate
A long-acting injectable testosterone ester used for testosterone replacement therapy. Clinically near-interchangeable with cypionate. Prescription medication.
HCG (Human Chorionic Gonadotropin)
A glycoprotein hormone produced in pregnancy that mimics luteinizing hormone, used clinically to stimulate gonadal function. It is studied to support testosterone production and fertility.
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Pharmacokinetics and dose finding of a potent aromatase inhibitor, aromasin (exemestane), in young males
2003
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A randomized trial of exemestane after two to three years of tamoxifen therapy in postmenopausal women with primary breast cancer
2004
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Exemestane for breast-cancer prevention in postmenopausal women
2011
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Overview of the pharmacology of the aromatase inactivator exemestane
2002