Purpose: In this open label, single arm, dose blinded, 52-week registration phase study we evaluated the efficacy and safety of a subcutaneous testosterone enanthate auto-injector administered weekly to men with hypogonadism.
Materials and methods: A total of 150 patients were initiated on a 75 mg subcutaneous testosterone enanthate auto-injector self-administered weekly. Dose adjustments were made at week 7 to 50, 75 or 100 mg testosterone enanthate based on the week 6 total testosterone trough concentration. If required, dose adjustments continued through the extended treatment phase. Pharmacokinetic and clinical laboratory parameters, treatment emergent adverse events and injection site reactions were captured.
Results: The primary end point was met since 92.7% of patients achieved an average total testosterone concentration of 300 to 1,100 ng/dl (mean ± SD 553.3 ± 127.29) at week 12. A maximum concentration of less than 1,500 ng/dl was achieved by 91.3% of patients and no patient had a level greater than 1,800 ng/dl at week 12. The mean total testosterone trough concentration was 487.2 ± 153.33 ng/dl at week 52. Of the patients more than 95% reported no injection related pain. The most frequently reported treatment emergent adverse events were increased hematocrit, hypertension and increased prostate specific antigen, which led to discontinuation in 30 men. There were no study drug related serious adverse events.
Conclusions: The dose adjusted subcutaneous testosterone enanthate auto-injector demonstrated a steady serum total testosterone pharmacokinetic profile with small peak and trough fluctuations. The device was safe, well tolerated and virtually painless, indicating that this subcutaneous testosterone enanthate auto-injector offers a testosterone delivery system that is a convenient weekly option to treat testosterone deficiency.