The FDA has approved two new oral formulations of testosterone undecanoate — Kyzatrex (Marius) and Tlando (Antares) — for treatment of males with a deficiency of endogenous testosterone due to conditions such as Klinefelter syndrome, orchiectomy, toxic damage from chemotherapy or alcohol, or pituitary-hypothalamic injury caused by tumors, trauma, or radiation. Jatenzo, another oral testosterone undecanoate formulation, was approved for the same indication in 2019. No testosterone products are approved for treatment of low testosterone levels due solely to aging.

Three coordinated double-blind, placebo-controlled clinical trials have evaluated the efficacy of one year of testosterone replacement therapy in improving sexual function, physical function, and vitality in a total of 790 men ≥65 years old with moderately low serum testosterone concentrations and symptoms suggesting hypoandrogenism. Sexual function improved modestly, and there appeared to be marginal benefits in some areas of physical function and vitality as well. The trials were not designed to evaluate the safety of testosterone replacement therapy.

The FDA has approved testosterone undecanoate (Aveed – Endo), an injectable depot formulation, for use in men with hypogonadism who require testosterone replacement therapy.

The Medical Letter recently reviewed a topical gel formulation of testosterone (Fortesta) for treatment of hypogonadism in men. A topical testosterone replacement product for application to the axilla, Axiron (Lilly) solution, has now become available for the same indication. This site of application presumably minimizes the risk of transferring the drug to a family member or sexual partner.

The FDA has approved Fortesta (Endo), a topical gel, for testosterone replacement therapy in adult males with hypogonadism. It is classified as a Schedule III controlled substance. Table 1 lists some available testosterone products, including 2 other gels.

Two new topical testosterone products, a 1% gel (Testim) and a buccal tablet (Striant), have been approved by the FDA for treatment of hypogonadism in men. This review briefly describes hypogonadism and its causes and lists other available formulations of testosterone. For the new products, information on pharmocokinetics, adverse effects, and dosage and administration is provided, as well as a summary of clinical trial results. A dosage and cost table for topical testosterone products is also included. The conclusion summarizes the safety and effectiveness of the new drugs and discusses the potential risks and benefits of using testosterone replacement therapy in older men.

Testosterone is now available in a 1% gel (AndroGel - Unimed) for treatment of hypogonadism in men. AndroGel, which is rubbed on the skin, is the fourth transdermal preparation of testosterone to be marketed in the USA.

Men with primary or secondary hypogonadism require lifelong androgen replacement to prevent osteoporosis and maintain normal muscle mass, erythropoiesis and sexual function (AM Matsumoto, Endocrinol Metab Clin North Am, 23:857, 1994). Until recently, the standard treatment for male hypogonadism has been an intramuscular injection of a long-acting testosterone ester every two to three weeks, which leads to serum testosterone concentrations that are high for a few days, normal for a few days more, and then may be subnormal until the next dose. Two transdermal preparations of testosterone are now marketed in the USA. Testoderm (Alza) must be worn on the scrotum. Androderm (SmithKline Beecham), a newer patch, can be applied to the upper arms, thighs, back or abdomen. All androgens are controlled substances in the USA.