Sildenafil for Diabetic Men With Erectile Dysfunction—Reply

In Reply: In response to Drs Garg and colleagues, serum testosterone and prolactin levels were measured in all the men with diabetes who were screened for our study of sildenafil in diabetic men with ED. Men with low testosterone or elevated prolactin levels were not eligible for enrollment.

In response to Drs Karlawish and Casarett, the decision to evaluate men who were in a stable relationship with a female partner in this phase 3 study is consistent with all the phase 3 trials conducted in the clinical development of sildenafil. The phase 3 studies were designed in consultation with the Food and Drug Administration (FDA) to generate data that would be applicable to the majority of men in the United States. Vaginal intercourse was chosen as the primary end point for these studies based on recently published data showing that it is the most commonly practiced sexual behavior in the United States.¹ This criterion also allowed for timely recruitment of subjects into the clinical trials. The same rationale for recruiting heterosexual men in studies of treatments for ED had been followed during registration studies for the 2 other agents with FDA approval (ie, intracavernosal alprostadil² and transurethral alprostadil³). As a result of these considerations, the 15-item International Index of Erectile Function questionnaire was developed with a focus on vaginal intercourse and was psychometrically validated to assess ED and responses to treatment.⁴ As suggested by Karlawish and Casarett, a validated questionnaire for the assessment of male-male sexual dysfunction is not currently available. The development and validation of such an instrument would be a valuable addition to the medical literature.