The combination of
Testosterone Decanoate, Isocaproate, Phenylpropionate, and Propionate was
developed to ensure both rapid and long-lasting release of testosterone. There
is no FDA approval for the combination, but the individual esters are medically
used for the treatment of hypogonadism. In bodybuilding, the mixture is used
for muscle growth and strength increase. PCT is necessary, as it strongly
suppresses natural testosterone production. The mixture was first introduced in
the 1960s and remains popular to this day.
