Testosterone Undecanoate
Testosterone ester, injectable. Half-life 20 days.
Also called Test U, Aveed, Nebido
Serum concentration from a single dose
single 100 mg dose over 14.3 weeks, vertical lines mark each half-life elapsed since the peak
What the numbers mean
At 20 days this is among the longest testosterone esters and takes months rather than weeks to reach steady state. Heavy ester weight leaves about 65% active testosterone.
The active fraction is the share of each milligram the model treats as reaching circulation as active compound. For an injectable that is ester weight: a milligram of enanthate is not a milligram of testosterone. For an oral it is bioavailability, the share that survives the gut and the liver, which is why some orals sit far below 100%. How the model works.
Where these numbers come from
No published reference is recorded for Testosterone Undecanoate. Its figures are carried over from the compound database this plotter was built against, and should be treated as the weakest in the set.
The peak and time to peak for the MCT oil preparation are estimated rather than measured. The castor oil version is the better documented of the two.
Common questions about Testosterone Undecanoate
What is the half-life of Testosterone Undecanoate?
The model uses a terminal half-life of 20 days for Testosterone Undecanoate. For an injectable that figure is the rate the oil depot releases the compound rather than the rate the body clears it, which is why it runs longer than the half-life of the ester itself.
How long does Testosterone Undecanoate take to reach steady state?
Roughly 14.3 weeks, on a schedule that does not change. Steady state is conventionally taken as five half-lives, the point at which each dose is clearing about as fast as the next one arrives, and at a half-life of 20 days that puts Testosterone Undecanoate at 14.3 weeks of climbing before the curve flattens.
How long does Testosterone Undecanoate stay in your system?
About 15.7 weeks after the last dose for the serum level to fall to a few percent of where it was, on the same five-and-a-half half-life reasoning. That is the modelled blood level only. It is not a detection window: metabolites are found by testing long after the parent compound has gone, and this model says nothing about that.
Put Testosterone Undecanoate on a timeline with the rest of your cycle and watch the curves add up.
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