IGF is a research drug, it hasn't been approved by the FDA for use as a pharmaceutical and it is currently being researched for nerve tissue repair, possible burn victims, and also as a possible aid in muscle wasting for AIDS patients.
There are many different analogs of IGF available, instead of mentioning them all, I will simply mention the two most common and the most effective. Regular recombinant IGF is one of the two, it is also the more expensive and the least effective. Regular IGF only has a half-life of about 10-20 minutes in the human body and is quickly destroyed, it can be combined with certain binding proteins to extend the half-life, but it is not a very simple procedure and there is a more effective and less expensive version available.
About IGF-1 Long R3
The most effective form of IGF is Long R3 IGF-1, it has been chemically altered and has had amino acid changes which cause it to avoid binding to proteins in the human body and allow it to have a much longer half life, around 20-30 hours. "Long R3 IGF-1 is an 83 amino acid analog of IGF-1 comprising the complete human IGF-1 sequence with the substition of an Arg® for the Glu(E) at position three, hence R3, and a 13 amino acid extension peptide at the N terminus. This analog of IGF-1 has been produced with the purpose of increasing the biological activity of the IGF peptide. It is also not as expensive since a media grade version is available which is sufficient for bodybuilding use.
Differences between IGF-1 and HGH (human growth hormone)
There is a lot of talk about the similarity between IGF and growth hormone. The most often asked question is simply which is more effective. GH doesn't directly cause your muscles to grow, it works very indirectly by increasing protein synthesis capabilities, increasing the amount of insulin a person can use effectively, and increasing the amount of anabolic steroids a person can use effectively. GH also indirectly causes muscle growth by stimulating the release of IGF when it (the GH) is destroyed in the human body. So one way you could look at it as GH being a precursor to IGF. So to put it simple IGF is more effective at directly causing muscle growth and density increases. IGF is also much more cost effective. IGF can also be effectively used by itself and gains will still be easily noticeable. With growth hormone you need to use high amounts of anabolics and often insulin to see any gains at all, this is not the case with IGF.
Igtropin IGF-1 Long R3 Quality Analysis Report