DrJMW said:
Subcutaneous (SC) vs. Intramuscular (IM)
Even though many people, including the HGH manufacturers, recommend SC injections of HGH, I do not agree. I prefer IM injections. This is based on pharmacology and clinical observation.
The advantages of injecting IM is one--less discomfort and adverse effects, and two--a greater increase in IGF levels than injecting into SC tissue (adipose). You still get the same fat burning effects that you would injecting SC, but you also get greater IGF levels doing so. SC Injection does not allow the HGH to get into the bloodstream to raise IGF levels. The HGH stays localized in the adipose tissue, only providing fat-burning.
I have spent 100's of hours doing research on medline with respect to hgh. There are different tradeoffs with respect to injecting hgh IV, IM, or SC. Here are some facts,
Injecting IV yields 100% absorption into the blood stream.
Injecting SC yields 75% absorption. (Humatrope)
Injecting IM yields 63% absorption. (humatrope)
So if you inject 10iu IM you only absorb 6.3IU, if you inject 10iu SC you only absorb 7.5IU................
If you look at the prescribing info for humitrope they include a graph. If you do the math you will find that for a 100kg person, 2iu SC will increase plasma concentrations by 2-4 ng/ml over a period of 8hr. 4ng/ml corresponding to the peak concentration, and 2ng/ml corresponding to the beginning and end of the 8hr period.
This amount of gh is around a normal persons baseline levels. You basically produce gh in spurts and in-between those spurts you have the baseline levels.
It has been determined in numerous studies the growth and especially IGF-1 production is greatly increased by continuos infusion of hgh, when compared to the same amount given in pulses. I have medline abstracts on these at work.
Basically the studies say that if you took 10IU of hgh IV spread out to 10-20 inj a day (to simulate your bodies pulses of gh production), and compared those results with 10IU being given IV but continuously over a 24hr period (maintaining the same blood concentration) your body would produce more IGF and linear growth from the continuous infusion. These studies suggest that IGF-1 production with response to gh is more a function of its baseline levels.
This is why you would get more IGF-1 by injecting IM. However, you will absorb less than you would if taken SC. The absorption ratio of IM over SC based on humitrope is 0.84. So if you inject IM you will only absorb 84 percent of the amount of gh as compared to SC.
The other thing is if you inj IM or SC feedback is going to occur through IGF-1 which has a long half-life. So taking it in the morning verses at night seems senseless.
http://pi.lilly.com/us/humatrope-pi.pdf