Efficacy and safety of testosterone replacement gel for treating hypogonadism in men: Phase III open-label studies

Efficacy and safety of testosterone gel 2% (TG) were evaluated in two phase 3, open-labelled, single-arm, multicentre studies (000023 and extension study 000077). Hypogonadal men having serum testosterone levels <300 ng/dl at two consecutive measurements were included. Study duration was 9 months (000023: 3 months; 000077: 6 months). Starting dose of TG (46 mg) was applied on upper arm/shoulder. The primary endpoint (000023) was responder rate (subjects with average 24-hour serum testosterone concentration 300-1050 ng/dl on Day 90). Study 000077 evaluated the safety of TG in patients rolling over from study 000023 over a period of 6 months. Of 180 subjects in 000023, 172 completed and 145 rolled over to 000077, with 127 completers. The responder rate was 85.5%. Fewer subjects in 000077 (12.7%) versus 000023 (31.8%) had maximum testosterone concentration (C_max ) >1500 ng/dl, with no significant safety concerns. Significant improvements in sexual function and quality of life were noted in both studies. Subjects experienced few skin reactions without notable increases in prostate-specific antigen and haematocrit levels. TG was efficacious with an acceptable safety profile. C_max >1500 ng/dl did not exhibit distinct impact on safety parameters. However, further optimisation of titration schema to reduce C_max is warranted while maintaining the average steady state total testosterone concentration.