19-nor anabolic steroids are testosterone-derived compounds modified by the removal of the 19th carbon atom, a change that significantly alters their metabolism and receptor activity.
Aromatization is the conversion of testosterone into estradiol. It is a key hormone-regulating process with wide effects on metabolism, bone health, cardiovascular function, and mood.
Unlike injectable steroids, oral compounds must pass through the liver before they enter systemic circulation — a process known as first-pass metabolism. During this phase, the liver attempts to break down and deactivate foreign substances. Most unmodified steroid molecules are rapidly degraded, resulting in extremely low oral bioavailability.