This was a comprehensive study done of the half-lives of various esters. This is real science using the scientific method to mark and record the half life of testosterone at various esters. Here were their findings compared to the often cited half life of esters. 1st variable is the community reported half life, the second variable is the "recorded" half life that was discovered.
Esters
Propionate: 2 days -> 0.8 days
Acetate: 3 days -> 1 day
Phenylpropionate: 4.5 days -> 1.5 days
Isocaproate: 9 days -> 4 days
Enanthate: 10.5 days -> 4.5 days
Cypionate: 12 days -> 5 days
Decanoate: 15 days -> 7.5 days
Undecanoate: 16.5 days -> 20.9 days
Other
Injectable Primobolan: 10.5 days -> 4.5 days (Injectable Primo uses the enanthate ester)
Injectable Winstrol: 2 days -> 1 day
But why is there such a huge difference?
Previous data has been pulled from studies involving the molecular half life of compounds. This new information uses the biological or terminal half life.
For our purposes, we really only care about the terminal half-life, defined as:
The biological half-life or elimination half-life of a substance is the time it takes for a substance (for example a metabolite, drug, signalling molecule, radioactive nuclide, or other substance) to lose half of its pharmacologic, physiologic, or radiologic activity, as per the MeSH definition.
