Ancillaries & PCT

Two mechanisms filed together by role rather than by pharmacology, both taken alongside or after a steroid cycle rather than for what they were developed to treat. Anastrozole and letrozole block aromatase reversibly and exemestane inactivates it, so less androgen is converted to oestrogen. Tamoxifen, clomifene and raloxifene act at the oestrogen receptor itself, blocking it in some tissues while activating it in others — which is what selective means in their name, and why they are not interchangeable with the inhibitors.

The assumption worth dismantling is that oestrogen is a side effect to be removed. Driving it down has its own costs — lipids, bone, mood, libido, joints — and an aromatase inhibitor can overshoot. Tamoxifen needs CYP2D6 to become active, so an SSRI that inhibits that enzyme works against it.