A Research Study of Injections of Testosterone in an Oil Vehicle for men with Androgen Deficiency: Reandron (Testosterone Undecanoate) will be administered subcutaneously and intramuscularly.

Although intramuscular (IM) injections of androgen's are known to be effective, they result in varying degrees of pain at the injection site that may last for a day or two. These injections need to be given into a precise location of the buttocks and require staff with expert training. Unlike many other injections these cannot be self-injected due to the difficulty of safely injecting into the buttocks. A SC injection, if effective, may be given by yourself in your own home, which would be more convenient to avoid extra medical visits as well as saving GP and hospital resources. Many men who require androgen replacement therapy may have bleeding disorders or are on medications that may intentionally slow the ability of their blood to clot. These men have a theoretical risk of bleeding and a very large bruise deep in an important muscle may later become infected and cause significant disability. As a result men using these anti-clotting drugs are usually prescribed other forms of androgen replacement therapy that are not always optimal. A subcutaneous (SC) injection, if effective, may be used in these men. This is a randomised crossover study of testosterone Undecanoate given subcutaneously and intramuscularly in patients receiving testosterone replacement therapy. Each participant will receive a single IM injection and a single (SC) injection of TU. An IM injection is standard of care and duration of action is approximately 12 weeks. It is expected a SC injection will have a duration of action of 12 weeks. Thus the study will take 24 weeks for each participant to complete both arms. This is the second stage of a 2 stage research study. This is stage 2 of study ACTRN12613000068763