Initial and subsequent success with PDE5 inhibitor treatment for erectile dysfunction: Results of a pooled analysis of a large integrated clinical trial database, "Beyond the Abstract," by Angelina Sontag, PhD and Raymond Rosen, PhD

BERKELEY, CA ( - Erectile dysfunction (ED) affects a majority of men by the time they reach their 60s.[1] Phosphodiesterase type 5 (PDE5) inhibitors are effective and well-tolerated treatments and are recommended as a first line of therapy for treatment of ED;[2] despite this, discontinuation of PDE5 inhibitors is relatively high.[3] One reason postulated for the discontinuation of PDE5 therapy in some patients is related to a lack of early success, which may affect patient satisfaction, and in turn, treatment continuation.[3, 4] It is important for clinicians to understand the extent to which early success and reliability of success may be a predictor of long-term treatment continuation and thus treatment effectiveness. This information would be useful for clinicians as they evaluate therapies and counsel patients on appropriate expectations for their ED treatment.

We utilized a large, placebo-controlled clinical trial database of tadalafil to confirm and expand upon earlier findings regarding the success rates and reliability of efficacy with PDE5 inhibitors. Data from 3 254 ED patients, treated on an as-needed basis with tadalafil (10 or 20 mg) or placebo, were pooled from 17 placebo-controlled studies and analyzed. We found that approximately 80% of patients on tadalafil were able to have their first successful penile insertion within two sexual attempts with either tadalafil dose. Furthermore, 80% of patients on tadalafil achieved their first successful intercourse within 8 sexual attempts for tadalafil 10 mg and 4 attempts for tadalafil 20 mg. However, approximately 70% of tadalafil-treated patients achieved their first successful intercourse even by the second sexual attempt. Subsequent overall success rates were higher for patients who had first-attempt success (82% and 86% for the tadalafil groups, versus 65% for placebo; p < 0.001), compared to patients who had successful intercourse with later attempts (53% and 56% for the tadalafil groups versus 40% for placebo; p < 0.001). Among patients treated with tadalafil, intercourse success rates during early attempts were similar to success rates at later attempts. Our results are in line with those of other studies[5, 6, 7] in pointing to a robust, highly generalizable effect of first-attempt intercourse success as a key factor in determining treatment outcomes in patients with ED receiving PDE5 inhibitor treatment.

However, these findings also suggest that continued pharmacotherapy for patients who fail to achieve first-attempt success with ED drugs can also lead to high rates of subsequent success. The majority of patients will have successful intercourse by the second attempt, but advising patients that it may take some men as many as 8 attempts before they are successful may help to set reasonable expectations. Subgroup characteristics such as ED severity and presence of diabetes can be expected to affect treatment outcomes. From a clinician’s perspective, these characteristics should be taken into consideration when counseling patients and setting expectations regarding efficacy of therapy, including importance of continued treatment and continued attempts, even in the case of initial failure.


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Written by:
Angelina Sontag, PhDa and Raymond Rosen, PhDb as part of Beyond the Abstract on This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.

aPrincipal Research Scientist, Men’s Health – Lilly Medical, Lilly USA, LLC
bNew England Research Institutes, Inc., Watertown, MA, USA

The Role of Initial Success Rates and Other Factors in Determining Reliability of Outcomes of Phosphodiesterase Inhibitor Therapy for Erectile Dysfunction: A Pooled Analysis of 17 Placebo-Controlled Trials of Tadalafil for Use as Needed - Abstract

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