New long-acting androgens.

Testosterone substitution treatment aims to replace physiological actions of endogenous testosterone by steadily maintaining physiological blood levels of testosterone. The underlying conditions rendering androgen replacement necessary are usually irreversible. The consequence is that almost life-long androgen replacement is required. Patient compliance with life-long androgen replacement depends on convenient pharmaceutical formulations ensuring continuity of androgen replacement. Therefore, they must be convenient in usage with a relative independence of medical services. In elderly man, safety of androgen replacement therapy is a concern but in younger subjects (below the age of 50 years) side effects of androgens are usually minimal. For them, long-acting testosterone preparations are well suited. Testosterone implants generate, depending on the dose of implants, 3-6 months of normal plasma testosterone. This method requires minor surgery. Injectable testosterone undecanoate maintains plasma testosterone in the normal range for 12 weeks.