Nandrolone phenylpropionate is a nandrolone ester, or a prodrug of nandrolone. As such, it is an androgen and anabolic steroid, or an agonist of the androgen receptor, the biological target of androgens like testosterone. Relative to testosterone, NPP has enhanced anabolic effects and reduced androgenic effects. In addition to its anabolic and androgenic activity, NPP has low estrogenic activity (via its metabolite estradiol) and moderate progestogenic activity. Like other AAS, NPP has antigonadotropic effects, which are due to both its androgenic and progestogenic activity.