Other significant adverse effects of testosterone supplementation include acceleration of pre-existing prostate cancer growth in individuals who have undergone androgen deprivation; increased hematocrit , which can require venipuncture in order to treat; and, exacerbation of sleep apnea .  Adverse effects may also include minor side-effects such as acne and oily skin, as well as, significant hair loss and/or thinning of the hair, which may be prevented with 5-alpha reductase inhibitors ordinarily used for the treatment of benign prostatic hyperplasia , such as finasteride .  Exogenous testosterone may also cause suppression of spermatogenesis , leading to, in some cases, infertility.  It is recommended that physicians screen for prostate cancer with a digital rectal exam and prostate-specific antigen (PSA) level before starting therapy, and monitor PSA and hematocrit levels closely during therapy. 
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.