Testosterone undecanoate (17beta;-undecanoyloxy-4-androsten-3-one) is an unsaturated, aliphatic, fatty acid ester of T. Testosterone undecanoate for intramuscular administration provides a long-acting testosterone depot (half-life of 33.9 +/−4.9 days) with favorable pharmacokinetic properties. In hypogonadal men, 1000 mg of Testosterone undecanoate can maintain stable plasma T levels for 12 weeks.

Testosterone undecanoate is indicated for replacement therapy in adult males with conditions that are linked with an absence or deficiency in endogenous testosterone production. Testosterone undecanoate also helps to maintain muscle and prevent bone loss, and is necessary for natural sexual ability/desire.

Testosterone undecanoate may also be used in certain adolescent boys to cause puberty in those with delayed puberty. This product should not be used by women.

Indications

Primary hypogonadism (congenital or acquired): testicular failure due to cryptorchidism, bilateral torsion, orchitis, vanishing testis syndrome, orchiectomy, Klinefelter's syndrome, chemotherapy, or toxic damage from alcohol or heavy metals. These men usually have low serum testosterone concentrations and gonadotropins (follicle-stimulating hormone [FSH], luteinizing hormone [LH]) above the normal range.

Hypogonadotropic hypogonadism (congenital or acquired): gonadotropin or luteinizing hormone-releasing hormone (LHRH) deficiency or pituitary-hypothalamic injury from tumors, trauma, or radiation. These men have low testosterone serum concentrations but have gonadotropins in the normal or low range.