Andarine (S-4)

Mechanism of Action

Andarine (S-4, GTx-007) is an early-generation aryl propionamide SARM that binds the androgen receptor with high affinity and tissue selectivity. It functions as a full agonist at AR in skeletal muscle and bone, promoting anabolic effects, while exhibiting partial agonist/antagonist activity in androgenic tissues (prostate, seminal vesicles). Andarine does not aromatize or undergo 5α-reduction. A notable distinguishing feature is its affinity for the visual pigment pathway — andarine can bind and temporarily alter rhodopsin-like proteins in the retina, causing a yellow-tinted vision effect in some subjects. This ocular side effect limited clinical development despite good anabolic efficacy.

Evidence Level

In Vivo - Animal

5 studies published