Gear concentration vs half life.

[BP_6]

Just wondering on others thoughts. Do we possibly not take into account that how concentrated per ml, the type of oil used, may affect a steroids half life beyond simply what ester is used standard?

For example, looking at the literature on Test U, castor oil was specifically chosen as they noticed in their testing this gave the longest half life with tea tree oil being a close 2nd. So if you put Test U in MCT oil as some UGL do, you likely will not get the same super long half life as the pharma version and the difference may be very tangible. What about for example, 600mg/ml EQ? Would that technically have a shorter half life if you were to inject it vs 2cc of 300mg/ml EQ?

Another old school example to look at is Parabolan. 76.5mg in 1.5ml. We know that the odd 76.5 number was used to give exactly 50mg of pure trenbolone after the ester was stripped, but why the odd 1.5 cc? Tren hex is about as painless of an injection as you get and holds perfect at 100mg/ml or more in 1 cc. Was the 1.5 to extend the half life a bit?

I don't know the answer to these, just speculating, but I would love to hear those who know more about the chemistry to chime in or anyone else just to give their thoughts.

 

[Photon]

Just wondering on others thoughts. Do we possibly not take into account that how concentrated per ml, the type of oil used, may affect a steroids half life beyond simply what ester is used standard?

It makes a difference, but not a significant difference.

For example, looking at the literature on Test U, castor oil was specifically chosen as they noticed in their testing this gave the longest half life with tea tree oil being a close 2nd. So if you put Test U in MCT oil as some UGL do, you likely will not get the same super long half life as the pharma version and the difference may be very tangible.

The half life gain from castor isn't simply by using castor. It is by
1) creating a thick low concentration, high viscosity oil
2) injecting a large amount into a single muscle (4ml)

This creates a depot, which takes much longer to be absorbed.
A depot created via MCT or tea tree, will be absorbed much quicker.

Most people will not get the same h/l gain as what was done in the studies, especially if you're pinning small amounts (e.g 1/2ml)

Higher concentration gear, typically contains less oil and more solvents.
Solvents in general, have much lower viscosity vs oil. e.g 550mg/ml Test U would almost be entirely made out of solvents+raws and very minimal oil, which defeats the purpose of even using castor. There's close to no castor at all!

Post in thread 'OEP LABS Domestic'

Sep 10, 2025

4ml of castor oil injected into 1 butt-cheek (250mg/ml)
vs
8ml of teaseed oil injected into both butt-cheeks (125mg/ml)

Half life difference,
(33.9+/-4.9 vs 20.9+/-6.0 days)

Intramuscular injection of testosterone undecanoate for the treatment of male hypogonadism: phase I studies - PubMed

The longer half-life and the smaller injection volume make TU in castor oil a strong candidate for further applications in substitution therapy and in trials for male contraception.

pubmed.ncbi.nlm.nih.gov

TU in a thin oil like MCT+EO that the Chinese use is def not going to give you a h/l of 30d.

• Photon

• 

What about for example, 600mg/ml EQ? Would that technically have a shorter half life if you were to inject it vs 2cc of 300mg/ml EQ?

I'll say yes, but the difference is probably not significant in any way.
1ml doesn't take long to absorb.

Pin 1ml and 4ml, see which creates a lump.


TLDR
Low concentration, high viscosity, high volume, single muscle = Longer h/l