Human Growth Hormone is an injectable hormone that can be administered subcutaneously or intramuscularly. When injected subcutaneously, HGH carries a bioavailability of approximately seventy-five percent. When injected intramuscularly, HGH carries a bioavailability of approximately sixty-three percent. The mode of administration will also affect the half-life of the Somatropin hormone. When injected subcutaneously, it will carry a half-life of approximately hours. When injected intramuscularly, it will carry a half-life of approximately hours. While this is a rather short half-life regardless of the mode of administration, keep in mind the total effects far outlast these numbers due to the pronounced and significant increases in IGF-1 production that stretch far past the twenty-four hour mark.
Claims for GH as an anti-aging treatment date back to 1990 when the New England Journal of Medicine published a study wherein GH was used to treat 12 men over 60.  At the conclusion of the study, all the men showed statistically significant increases in lean body mass and bone mineral density, while the control group did not. The authors of the study noted that these improvements were the opposite of the changes that would normally occur over a 10- to 20-year aging period. Despite the fact the authors at no time claimed that GH had reversed the aging process itself, their results were misinterpreted as indicating that GH is an effective anti-aging agent.    This has led to organizations such as the controversial American Academy of Anti-Aging Medicine promoting the use of this hormone as an "anti-aging agent". 
Others purchase HGH products -- or products that claim to increase your body's own production of HGH -- in the form of pills and sprays. Companies that market these products on TV infomercials or online claim they turn back your body's biological clock, reducing fat, building muscle, restoring hair growth and color, strengthening the immune system, normalizing blood sugar , increasing energy and improving sex life, sleep quality, vision , and memory. However, the Federal Trade Commission has seen no reliable evidence to support the claim that these products have the same effects as prescription HGH, which is always given by injection. Taken orally, HGH is digested by the stomach before it can be absorbed into the body.