How Anastrozole Works
Anastrozole is a third-generation aromatase inhibitor that blocks the conversion of androgens to estrogens. The aromatase enzyme turns androgens such as testosterone into estrogens, mainly estradiol; aromatase inhibitors reduce estrogen production by binding to the aromatase enzyme, which lowers estrogen levels. PubMed CentralPubMed Central
What It Is Approved For
Anastrozole is FDA-approved to treat hormone-receptor–positive breast cancer in postmenopausal women, and its labeling flags safety issues including bone mineral density loss and changes in cholesterol. The commercial product is a 1 mg tablet. PubMed Central
Why It Is Compounded as a Capsule
Because the only commercial strength is a 1 mg tablet, a prescriber who wants a different strength — often a precise dose below 1 mg — may order compounded capsules made to that exact specification. Capsules also allow dye-free or filler-conscious versions for sensitive patients.
A Note on Off-Label Use
Some prescribers use anastrozole off-label. In men on testosterone therapy with elevated estradiol, reported regimens have used small doses such as 0.5 mg three times weekly to lower estradiol while maintaining testosterone. Aromatase inhibitors have also been studied in boys to delay bone maturation and influence adult height, but long-term safety in males is not established and routine use is not recommended. These uses are not FDA-approved; whether and how to use anastrozole is the prescriber's clinical decision. DovepressPubMed Central
Clinical Context and Safety
Anastrozole lowers estrogen, and estrogen has important roles in bone, lipids, and other systems in both women and men. Selection, dosing, and monitoring are the prescriber's responsibility.
Quality and Compliance
Mixwell Compounding Pharmacy prepares these capsules in our purpose-built, USP <795>-compliant lab to the prescriber's exact instructions, dispensed only with a valid prescription. Mixwell is a non-sterile pharmacy and does not prepare sterile products or injectables. Compounded medications are not reviewed or approved by the FDA. Nothing here promises a specific result, and compounded preparations are not presented as superior to commercially available products.
References
- Punjani N, Bernie H, Salter C, et al. The Utilization and Impact of Aromatase Inhibitor Therapy in Men With Elevated Estradiol Levels on Testosterone Therapy. Sex Med. 2021;9(4):100378. doi:10.1016/j.esxm.2021.100378.
- de Ronde W, de Jong FH. Aromatase inhibitors in men: effects and therapeutic options. Reprod Biol Endocrinol. 2011;9:93.
- ARIMIDEX (anastrozole) Prescribing Information. U.S. Food and Drug Administration.
- Professional Compounding Centers of America (PCCA). Formulation science and compounding resources. https://www.pccarx.com/Blog/