Intraurethral alprostadil has been approved by the U.S. Food and Drug Administration as a system to treat patients with erectile dysfunction (ED). While efficacy for the system was demonstrated in published clinical trials, the investigators in this study said that they were disappointed with initial results in their own clinical practice.

Consequently, they decided to conduct their own trial with 115 male patients, who were approximately 65 years old; all had a regular sexual partner. They patterned their study after the initial New England Journal of Medicine report on the system. Almost 51% of the patients were college-educated, with almost 29% having postgraduate training. On a scale of 1 to 10, they rated their health at 8.1, but their sexual functioning at 3.5.

Most of the men had either had surgical treatment for prostate cancer or suffered from diabetes. After the trial started, the men received in-office treatment with increasing doses of intraurethral alprostadil. After use, the patients ga ve a self-rating on penile rigidity from 1 to 5, plus a personal level of comfort rating. The ratings 4 and 5 were considered sufficient for intercourse.

The patients also received blood pressure checks at 15-minute intervals. According to the investigators, peak rigidity was achieved at 30 minutes with a score of 2.6 at 250 mcg, 2.4 at 500 mcg, and 2.9 at 1000 mcg. Only 27% of the patients achieved rigidity sufficient for intercourse despite being challenged to the highest doses. According to the researchers, discomfort was maximal at 15 minutes with ratings of 3.5 (250 mcg), 3.7 (500 mcg), and 4.2 (1000 mcg). Blood pressure decreased significantly at 15 and 30 minutes.

Penile pain and burning were the most common adverse events. At follow-up, according to the researchers only 18.6% of the patients continued to use the system, while the majority chose alternate treatments. The investigators concluded: "For a variety of possible reasons efficacy in a controlled clinical trial has not translated into clinical usefulness of the MUSE system for the majority of our patients suffering from ED."