Testosterone can be administered parenterally , but it has more irregular prolonged absorption time and greater activity in muscle in enanthate , undecanoate , or cypionate ester form. These derivatives are hydrolyzed to release free testosterone at the site of injection; absorption rate (and thus injection schedule) varies among different esters, but medical injections are normally done anywhere between semi-weekly to once every 12 weeks. A more frequent schedule may be desirable in order to maintain a more constant level of hormone in the system.  Injectable steroids are typically administered into the muscle, not into the vein, to avoid sudden changes in the amount of the drug in the bloodstream. In addition, because estered testosterone is dissolved in oil, intravenous injection has the potential to cause a dangerous embolism (clot) in the bloodstream.
Ligand Pharmaceuticals has patents filed for the manufacture and therapeutic use of certain compounds occupying several stated chemical structures, which are intended for use as selective androgen receptor modulators. The patent is filed under the following designations: US8519158 B2, US8865918, US9359285, US20070254875, US20140005186, US20150099720, and WO2005090282A1. The patents will expire on March 12, 2025. These patents effectively protect any future capitalization upon VK5211 in the market by Viking and Ligand through their licensing agreement.