Steroid release observations...

heroish

New Member
I am not sure if this is useful to anyone but... :)

After a fair bit of experimenting, including blood tests, I have noticed the following about half lives / ester release:

1. Injection location matters (delts vs glutes etc) - glutes are much slower releasing and have a more stable release profile - makes sense given size of muscle, formation of depot and blood flow. Also, for SubQ I have noticed the butt / love handle area has a much slower release than thigh fat... Diabetic studies seem to confirm this difference in release from different sites... Subq is def more stable than IM.

2. Carrier oil has a huge impact - a notable difference between grapeseed and castor oil (/sesame seed oil). GSO release significantly quicker in my body than castor oil...

3. Injection volume and frequency - the more injected in one site the slower the release (sounds obvious given the depot formation), however, not enough to offset the impact of frequency - much better to inject more often for stability.

I am pretty much just doing TrT at the moment but I do feel a lot better, and find estrogen easier to control, when blood levels are stable.

To ensure stability I use a long lasting ester (enanthate), inject three times a week, use a longer lasting carrier oil (castor oil), inject subq into butt fat. This makes an incredibly huge difference to keeping blood levels stable (more than double the half life from the best to worst combination I would guess).

It seems obvious all of the above and I can dig up studies backing up most of the above if anyone is interested.
 
A study showing that testosterone undeconate shot in a single glute using castor oil carrier has over a 50% increase in half life (33 vs 20 days) vs a double glute shot using tea seed oil:

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.503.1752&rep=rep1&type=pdf

Abstract Objective: In the search for long-acting testosterone preparations suited for substitution therapy of hypogonadal men, testosterone undecanoate (TU) dissolved in either tea seed oil or castor oil was investigated. Design: In study I, 1000 mg TU in tea seed oil (125 mg/ml) were injected in equal parts into the gluteal muscles of seven hypogonadal men. In study II, 1000 mg TU in castor oil (250 mg/ml) were injected into one gluteal muscle of 14 patients.

Results: In comparison with published data on testosterone enanthate, most widely used for i.m. injections, the kinetic profiles of both TU preparations showed extended half-lives and serum levels not exceeding the upper limit of normal. The castor oil preparation had a longer half-life than TU in tea seed oil (33.9 +- 4.9 vs 20.9 +- 6.0 days (mean 6 S.E.M.)).

Conclusion: 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.
 
Is there a study comparing different half lives with popular oils like GSO, MCT, etc along with castor oil? I wonder if castor oil could make injectable orals more effective with a longer absorption time.
 
Unfortunately I can't find any with grapeseed oil. MCT oil you can find a few studies on both animals and humans - here is one:

From, Intramuscular rate of disappearance of oily vehicles in rabbits investigated by gamma-scintigraphy, Kirsten Schultz et al, International Journal of Pharmaceutics 169 (1998) 121–126

Viscosities and muscular disappearance rates of various oily vehicles
Oily vehicle - Viscosity at 37°C - T1/2
  • Ethyl oleate - 3.9 - 10 days
  • Fractionated coconut oil - 15 - 1 week
  • Sesame oil - 35 - 1 month
  • Arachidis oil - 35.2 - 23 days
  • Castor oil - 286 - Indefinitely
MCT oils are very quick release and castor / sesame is slow. In humans castor oil does clear and there are studies on it having a very slow clearence rate. Similarly, MCT oil releases very quickly in humans.

If anyone has anything on GSO would be useful - it is the oil of choice it seems but most EU/INTL pharma does not use it.
 

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