It has been suggested that the prevalence of use among high-school students in the U. In order to be sufficiently active when given by mouth, testosterone derivatives are alkylated at the 17α position, e.g. This modification reduces the liver's ability to break down these compounds before they reach the systemic circulation.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.
According to a recent survey, 78.4% of steroid users were noncompetitive bodybuilders and non-athletes, while about 13% reported unsafe injection practices such as reusing needles, sharing needles, and sharing multidose vials, Another 2007 study found that 74% of non-medical AAS users had post-secondary degrees and more had completed college and fewer had failed to complete high school than is expected from the general populace.Injection is the most common method used by individuals administering AAS for non-medical purposes.The traditional routes of administration do not have differential effects on the efficacy of the drug.AAS use in adolescence is also correlated with poorer attitudes related to health. Development of breast tissue in males, a condition called gynecomastia (which is usually caused by high levels of circulating estradiol), may arise because of increased conversion of testosterone to estradiol by the enzyme aromatase.Another male-specific side-effect that can occur is testicular atrophy, caused by the suppression of natural testosterone levels, which inhibits production of sperm (most of the mass of the testes is developing sperm).