Open-Label, Crossover Study of Sildenafil Citrate and Tadalafil for the Treatment of Erectile Dysfunction in Patients Naive to Phosphodiesterase 5 Inhibitor Therapy.

Open-Label, Crossover Stud), of Sildenafil Citrate and Tadalafil for the Treatment of Erectile Dysfunction in Patients Naive to Phosphodiesterase 5 Inhibitor Therapy, Ian Eardley, Vincenzo Mirone, Francesco Montorsi, and Phillip Kell, Archway Sexual Health Clinic, United Kingdom; Yanli Zhao, Mark Harrison, and Anthony Beardsworth, Eli Lilly and Company 

We compared the efficacy, choice of treatment, and tolerability of sildenafil citrate (sildenafil) and tadalafil for the treatment of erectile dysfunction (ED) in patients naive to phosphodiesterase 5 (PDE5) inhibitor therapy. We conducted an open-label, crossover study of sildenafil and tadalafil, taken as needed. After a 4-week baseline assessment, men with ED (N = 367; mean age = 54 years) were randomized to sildenafil for 12 weeks followed by tadalafil for 12 weeks, or vice versa. Each 12-week period included an 8-week dose-optimization phase and 4-week assessment phase. During dose optimization, patients started with 25 or 50 mg sildenafil, or 10 mg tadalafil (per the SPC) and could titrate up and down to find their optimum dose of 25, 50, or 100 mg sildenafil, or 10 or 20 mg tadalafil. Men completing both 12-week periods chose which treatment to continue during an 8-week extension phase. Efficacy was measured with the International Index of Erectile Function (IIEF) and Sexual Encounter Profile (SEP) diary. Emergent adverse events were collected throughout the study. At baseline, 39%, 30%, and 31% of men had mild, moderate, or severe ED. A total of 294 men completed both treatment periods, and 29% (n = 85) of these men chose to continue with sildenafil; 71% (n = 206) chose to continue with tadalafil for the 8-week extension. The medication choice for the extension phase was not affected by treatment sequence, ED severity, or etiology, age, or dosage. Sildenafil and tadalafil were well-tolerated, with 11 (3.0%) men discontinuing for an adverse event and 3 (0.8%) men for lack of efficacy.