Testosterone undecanoate, sold for use by mouth under the brand names Andriol and Jatenzo and for use by injection under the brand names Aveed and Nebido, is an androgen and anabolic steroid (AAS) medication which is used mainly in the treatment of low testosterone levels in men. It is also used in hormone therapy for transgender men. It is taken by mouth two to three times per day with food or given by injection into muscle once every 3.5 days to 2 weeks, depending on individual response.
Side effects of testosterone undecanoate include symptoms of masculinization like acne, increased hair growth, voice changes, hypertension, elevated liver enzymes, hypertiglyceridemia, and increased sexual desire. The drug is a prodrug of testosterone, the biological ligand of the androgen receptor (AR) and hence is an androgen and anabolic steroid. It has strong androgenic effects and moderate anabolic effects, which make it useful for producing masculinization and suitable for androgen replacement therapy.Testosterone undecanoate is a testosterone ester and a prodrug of testosterone in the body. Because of this, it is considered to be a natural and bioidentical form of testosterone.
Testosterone undecanoate was introduced in China for use by injection and in Europe for use by mouth in the 1970s. It became available for use by injection in Europe in the early to mid 2000s and in the United States in 2014. A formulation for use by mouth is not currently available in the United States but is pending approval as of 2018. Along with testosterone enanthate, testosterone cypionate, and testosterone propionate, testosterone undecanoate is one of the most widely used testosterone esters. However, it has advantages over other testosterone esters in that it can be taken by mouth and in that it has a far longer duration when given by injection. In addition to its medical use, testosterone undecanoate is used to improve physique and performance.
Testosterone undecanoate is used in androgen replacement therapy. It is specifically approved only for the treatment of hypogonadism. As an intramuscular injection, it is administered at a dosage of 1,000 mg once every 12 weeks. Conversely, oral testosterone undecanoate must be taken two or three times a day with food.