Novel testosterone gel improves serum testosterone concentrations and aging males' symptoms in patients with late-onset hypogonadism: an active control equivalence, randomized, double-blind, crossover study

Late-onset hypogonadism (LOH) is generally treated with testosterone replacement therapy. Intramuscular injection of testosterone enanthate is used for LOH in Japan but requires regular painful injections administered every 2-3 weeks at a clinic. Testosterone 2% (AndroForte 2 (R) [AF2]) is available for treating LOH but is expensive because it is imported. We developed a new 2% testosterone gel (NTG) and hypothesized that in patients with LOH, NTG would improve serum testosterone concentrations and Aging Males' Symptoms (AMS) scores compared with AF2. We enrolled men with low levels of serum free testosterone (<11.8 pg/mL) and androgen deficiency symptoms (AMS score >27). The primary endpoint was equivalent change in serum testosterone concentrations with NTG compared to AF2. Secondary endpoints were equivalent change in AMS scores for each question with NTG compared to AF2. Each of AF2 or NTG was administered to the study subjects (23 men aged 42-71 years) for 4 weeks separated by a washout period of 2 weeks. The subjects were randomly divided into men who first received NTG and those who first received AF2. No subject experienced any adverse events throughout the study. Compared with the baseline values of serum testosterone, those following NTG and AF2 treatment were significantly higher and were also significantly higher in the subjects taking NTG versus AF2. NTG administration significantly improved the AMS score, whereas AF2 did not. This initial study has shown that this new NTG formulation may be effective in improving serum testosterone concentrations and also LOH-related symptoms.