Figure 2.

A, Illustration of the progressive increase in lipophilicity of testosterone esters with increase in number of carbons in the side chain. B, Schematic illustration of the absorption steps of testosterone esters after intramuscular (left) or subcutaneous (right) injection. With administration using either route, the ester exits the depot via diffusion into the interstitium, from where it enters the lymphatics and subsequently reaches the circulation where it undergoes hydrolysis by intracellular esterases. Testosterone ester is also partly hydrolyzed within the interstitium, with free testosterone entering the circulation directly.