What Testosterone is

Class and mechanism

Testosterone is an endogenous androgen; the reference androgen. The principal endogenous androgen in men, acting at the androgen receptor and, via aromatase, as the substrate for endogenous oestradiol. Supplied as esters, which alter release rate but not the parent hormone delivered.

Where it sits

Injectable compounds are supplied in oil. The ester attached to the molecule sets the release profile, which is why the same base compound appears under several different names.

Worth knowing

Blends such as Sustanon 250 combine several esters to produce a composite release curve from a single injection.

Other names

Testosterone is also written as Test. The same molecule appears under more than one name, which is worth knowing when comparing listings between suppliers.

Others in the injectable compounds range

Testosterone sits in the injectable compounds group. The compounds below share that grouping, which is the useful starting point when comparing one against another: same group means the comparison is like for like, different group usually means it is not.