SAN FRANCISCO — Adding testosterone replacement therapy to treatment with sildenafil provided short-term improvements in erectile dysfunction in a study of 75 hypogonadal men who did not respond to sildenafil alone, Ridwan Shabsigh, M.D., said at the annual meeting of the American Urological Association.

When 100 mg/day of the phosphodiesterase type 5 (PDE5) inhibitor sildenafil failed to improve erectile dysfunction symptoms, patients were randomized to add daily applications of a topical testosterone gel or a placebo gel. Among 67 men who completed 4 weeks of treatment, the testosterone group had improvements in erectile response, orgasmic function, and overall patient satisfaction, compared with the placebo group, said Dr. Shabsigh of Columbia University, New York, and also director of the New York Center for Human Sexuality.

Trends toward greater efficacy in the testosterone group after 8 and 12 weeks were not statistically significant.

Dr. Shabsigh has been a consultant, advisor, investigator, meeting participant, and lecturer for the companies that make sildenafil and the testosterone gel used in the study (AndroGel) — Pfizer Inc. and Solvay Pharmaceuticals Inc., respectively.

“It is important to screen men who present with erectile dysfunction for the presence of hypogonadism, especially populations at risk such as aging men, men with type 2 diabetes, men with the metabolic syndrome, and specifically men who fail PDE5 inhibitor therapy alone,” he said. “Testosterone may be considered for the treatment of erectile dysfunction in men with low to low-normal testosterone who fail PDE5 inhibitor therapy alone.”

Patients in the study had a mean age of 59 years, similar to the mean ages in most medical trials of PDE5 inhibitors for erectile dysfunction. They conducted the trial after clinical observations and animal studies suggested a synergistic effect when various forms of testosterone were used with various PDE5 inhibitors.