Drug Attributes Influencing the Choice of Sildenafil Citrate and Tadalafil for the Treatment of Erectile Dysfunction in an Open-Label, Crossover Study

Journal of Sex Research, Feb, 2006

Drug Attributes Influencing the Choice of Sildenafil Citrate and Tadalafil for the Treatment of Erectile Dysfunction in an Open-Label, Crossover Study, John Dean, Department of Urology, United Kingdom; Geoff Hackett, Good Hope Hospital, United Kingdom; Vincenzo Gentile, Dipartimento di Urologia; Furio P. Farina, Department of Andrology; Yanli Zhao, Mark Harrison, and Anthony Beardsworth, Eli Lilly and Company

We identified attributes of sildenafil citrate (sildenafil) and tadalafil that influence choice of medication for treatment of erectile dysfunction (ED) by conducting an openlabel, crossover study of sildenafil and tadalafil, taken as needed by patients naive to phosphodiesterase 5 (PDE5) inhibitors. 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. Reasons for treatment choice were assessed with a drug attributes questionnaire which listed 7 beneficial attributes of ED treatment that subjects could select to explain their choice of sildenafil or tadalafil. Patients were asked to select the best and second best reasons why they chose sildenafil or tadalafil. Of 294 men completing both treatment periods, 29% (n = 85) chose sildenafil and 71% (n = 206) chose tadalafil for the 8-week extension. Medication choice for the extension phase was not affected by treatment sequence, ED severity, or etiology, age, or dosage. Questionnaire responses (T = men choosing tadalafil; S = men choosing sildenafil) included Was able to get an erection long after having drug (T = 138, S = 6); The firmness of erections (T = 73, S = 51); Was able to get an erection every time (T = 45, S = 34); Had erections the next morning (T = 62, S = 7); Time between drug and 1st erection was short (T = 18, S = 35); Had few side effects (T = 29, S = 14); and Partner preferred this treatment (T = 27, S = 10). The drug attribute questionnaire identified various reasons men chose sildenafil or tadalafil, with the duration of drug effect selected most frequently as the attribute for choosing tadalafil.