A Comparison of Side Effects in Hypogonadal Men Treated With Natesto Versus Testosterone Injections

Administration of exogenous testosterone as efficacious treatment for male hypogonadism has been part of medical practice for more than 50 years. Testosterone replacement therapy (TRT) is becoming more widely available and has seen a greater than three-fold increase in use in men 40 years and older. Current delivery systems of TRT include transdermal gels and patches, intranasal gels (currently marketed as Natesto), injection therapy, and long acting subcutaneous pellets. Natesto is a short-acting formulation of testosterone delivered intranasally to men diagnosed with low T. This has the potential to avoid side effects related to TRT that are commonly seen with other delivery methods, namely polycythemia, acne, male-pattern hair loss, azoospermia and hyperestrogenemia. Testosterone Cypionate injections are the most common form of TRT in the USA. Testosterone Cypionate has many reported side effects, the most common being polycythemia, gynecomastia, hair loss, acne, decreased spermatogenesis, and testicular atrophy. In a multicenter retrospective study, it has been shown that the prevalence of polycythemia in men on testosterone replacement (injections) was 11.2%. In this study, we will compare hematocrit changes caused by treatment with Testosterone Cypionate and Natesto in a parallel arm, randomized study. To date, there have been no direct head-to-haed comparisons of these formulations. We hypothesize that the short-acting pharmacokinetics of Natesto more closely resembles the natural pulsatility of testosterone and therefore can avoid side effects traditionally seen in long-acting, exogenous testosterone formulations