The efficacy and safety of tadalafil, dosed once a day for the treatment of erectile dysfunction, was assessed in a randomized, double-blind, placebo-controlled, parallel-design study at 15 US centers. Following a 4-week treatment-free run-in period, patients (⩾18 years of age) were randomly assigned to 24 weeks treatment with tadalafil 2.5 mg, tadalafil 5 mg or placebo. Primary efficacy endpoints were change at 24 weeks in International Index of Erectile Function Erectile Function (EF) Domain score and mean per-patient percentage ‘yes’ responses to Sexual Encounter Profile diary questions 2 and 3. Tadalafil significantly improved erectile function compared with placebo for all three co-primary efficacy endpoints. Few patients discontinued because of adverse events (2.1%, placebo; 6.3%, tadalafil 2.5 mg; 4.1%, tadalafil 5 mg). Common treatment-emergent adverse events (⩾5%) were nasopharyngitis, influenza, viral gastroenteritis and back pain. Tadalafil 2.5 mg and 5 mg, dosed once a day for 24 weeks, was well tolerated and significantly improved erectile function.
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We acknowledge the additional study investigators: Stephen Auerbach, MD; Bradley Davis, MD; Eugene Dula, MD; Robert Feldman, MD; Darrell N. Fiske, MD; Michael Gambla, MD; Joel Kaufman, MD; Ira Klimberg, MD; Gary Ruoff, MD; David R Talley, MD; and Jay Young, MD. We thank Kate Loughney, PhD, ICOS Corporation for help in preparation of the manuscript and Steven D Watts, MS, Eli Lilly and Company for statistical analyses.
Study (study code H6D-MC-LVFP) funded by Lilly ICOS LLC.
Conflict of Interest Statements
Dr J Rajfer
Grants, Advisory Board, and Consultant for Lilly ICOS LLC, Pfizer, Bayer, Glaxo SmithKline.
Dr PJ Aliotta
Principal Investigator, Speaker, and Consultant for Lilly ICOS LLC, Pfizer, Glaxo SmithKline, Watson Pharmaceuticals, Novartis, Schering Plough; Principal Investigator and Consultant for Alza Pharmaceuticals, Speaker and Consultant for Boehringer Ingelheim and Ortho McNeil Pharmaceuticals.
Dr CP Steidle
Speaker and consultant for Lilly ICOS LLC, Speaker and Investigator for Pfizer, Bayer GSK.
Dr WP Fitch III
Speaker, Grant Support, Consultant for Lilly ICOS LLC, Speaker and Grant Support for Glaxo SmithKline, Grant Support from Johnson and Johnson.
Dr Y Zhao
Employee, Eli Lilly and Company.
Dr A Yu
Employee, ICOS Corporation.
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Rajfer, J., Aliotta, P., Steidle, C. et al. Tadalafil dosed once a day in men with erectile dysfunction: a randomized, double-blind, placebo-controlled study in the US. Int J Impot Res 19, 95–103 (2007). https://doi.org/10.1038/sj.ijir.3901496
- erectile dysfunction
- PDE5 inhibitor
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