Systematic Review of Oral Combination Therapy for Erectile Dysfunction When Phosphodiesterase Type 5 Inhibitor Monotherapy Fails.

INTRODUCTION

On-demand phosphodiesterase type 5 inhibitor (PDE5i) monotherapy is a first-line treatment for erectile dysfunction (ED), but 30%-40% of patients exhibit little or no response. The success rate of alprostadil therapy is high in these patients, but this treatment requires painful intracavernosal injection.

AIM

To systematically review the efficacy and safety of second-line oral pharmacologic combination therapies of ED when PDE5i monotherapy fails.

METHODS

PubMed and Embase were searched to identify reports providing quantitative data on the treatment of ED in patients failing PDE5i monotherapy.

MAIN OUTCOME MEASURES

The measures of erectile function were the International Index of Erectile Function (IIEF) and the Erectile Function Domain (EFD).

RESULTS

Chronic treatment with the PDE5i tadalafil alone or in combination with sildenafil on demand showed similar IIEF-5 score improvements. None of the 3 randomized controlled trials (RCTs) in patients who had failed PDE5i monotherapy found a superior effect on IIEF scores from the combination of androgen plus PDE5i compared with PDE5i monotherapy. Combination therapy with androgen supplementation and PDE5i appears safe. In 1 RCT, combination therapy with PDE5i and an α-adrenoceptor antagonist was not superior to PDE5i monotherapy. Six other studies, each with a different combination of PDE5i and another drug (eg, metformin, folic acid, 5-alpha-reductase inhibitors), were identified, but further research is required to investigate their efficacy in treating ED.

CONCLUSION

For ED, chronic treatment with low-dose PDE5i can be attempted when standard on-demand regimens fail. Combination therapy with androgen supplementation and a PDE5i appears to be safe. The combination of an α-adrenoceptor antagonist and PDE5i shows no advantageous effect on ED compared with PDE5i monotherapy. The efficacy of combining PDE5i with metformin, folic acid, or 5-alpha-reductase inhibitors is uncertain and requires further research. There is an unmet need for oral treatment of ED in nonresponders to PDE5i treatment. Munk NE, Knudsen JS, Comerma-Steffensen S, et al. Systematic Review of Oral Combination Therapy for Erectile Dysfunction When Phosphodiesterase Type 5 Inhibitor Monotherapy Fails. Sex Med Rev 2019;7:430-441.