Anastrozole vs Exemestane — compared

The short answer. Both are aromatase inhibitors, and the textbook distinction is reversible vs irreversible: anastrozole is a non-steroidal, reversible AI, while exemestane is a steroidal, irreversible ('suicide') inhibitor. They're different chemical classes that reach a similar end.

Side by side

	Anastrozole	Exemestane
Class	Ancillaries	Ancillaries
Form	Oral	Oral
Half-life	≈ 2.1 days (50 h)	≈ 24 hours
Storage	Room temperature	Room temperature
Dose units	mg	mg
FDA status	Approved	Approved

Facts from the Stack compound library. See the full pages: Anastrozole · Exemestane.

How they differ

Class

Anastrozole is non-steroidal and binds the aromatase enzyme reversibly. Exemestane is steroidal and binds irreversibly — the enzyme has to be remade. Same target, different chemistry.

Practical implication

The reversible-vs-irreversible difference is the main thing people mean when they compare these. How that maps to any individual's use is strictly a clinician's call.

Tracking

Both are orals taken on a schedule alongside other compounds; both fit cleanly into a protocol group you can pause as a unit.

Status

See each entry for FDA status — stated plainly on every library page.

Tracking either one

Whichever you log, the workflow is the same in Stack: add it once, set the schedule, and let the app handle reminders, supply projection and an "in your system" curve from the half-life. Run both? Group them into one protocol you can pause together.

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Not medical advice. This page compares publicly-documented properties of two compounds for educational purposes. It does not recommend either one, or any dose. How we source →

Last reviewed 2026-06-11