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J Sex Med. 2006 Jul;3(4):650-661. doi: 10.1111/j.1743-6109.2006.00261.x.

Psychosocial outcomes and drug attributes affecting treatment choice in men receiving sildenafil citrate and tadalafil for the treatment of erectile dysfunction: results of a multicenter, randomized, open-label, crossover study.

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The Prostate Center, London, UK;. Electronic address:
Good Hope Hospital, Lichfield, Staffordshire, UK.
Department of Urology, University of Rome La Sapienza, Rome, Italy.
Department of Urology, University of Sassari, Sassari, Italy.
Department of Psychiatry, UMDNJ-Robert Wood Johnson Medical School, Piscataway, NJ, USA.
Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA.
Eli Lilly and Company, Windlesham, UK.



Although sildenafil citrate (sildenafil) and tadalafil are efficacious and well-tolerated treatments for erectile dysfunction (ED), preference studies have shown that patients may favor one medication over the other.


To determine whether psychosocial outcomes differed when men with ED received tadalafil compared with sildenafil.


Measures included a treatment preference question, Psychological and Interpersonal Relationship Scales (PAIRS), and Drug Attribute Questionnaire.


Randomized, open-label, crossover study. After a 4-week baseline, men with ED (N = 367; mean age = 54 years; naïve to type 5 phosphodiesterase inhibitor therapy) were randomized: tadalafil for 12 weeks then sildenafil for 12 weeks or vice versa (8-week dose optimization/4-week assessment phases). During dose optimization, patients started with 10 mg tadalafil, or 25 or 50 mg sildenafil and could titrate to their optimal dose (10 or 20 mg tadalafil; 25, 50, or 100 mg sildenafil). Medications were taken as needed. Patients completing both 12-week periods chose which medication to continue during an 8-week extension.


Of 291 men completing both treatment periods, 71% (N = 206) chose tadalafil and 29% (N = 85) chose sildenafil (P < 0.001) for the 8-week extension. When taking tadalafil compared with sildenafil men had higher mean endpoint scores on PAIRS Sexual Self-Confidence (tadalafil = 2.91 vs. sildenafil = 2.75; P < 0.001) and Spontaneity (tadalafil = 3.32 vs. sildenafil = 3.17; P < 0.001) Domains and a lower mean endpoint score on Time Concerns Domain (tadalafil = 2.2 vs. sildenafil = 2.59; P < 0.001). The two most frequently chosen drug attributes to explain treatment preference were ability to get an erection long after taking the medication and firmness of erections. Tadalafil and sildenafil were well tolerated with 12 (3.3%) patients discontinuing for an adverse event.


As measured with PAIRS, men with ED had higher sexual self-confidence and spontaneity and less time concerns related to sexual encounters when treated with tadalafil compared with sildenafil. These psychosocial outcomes may help explain why more men (71%) preferred tadalafil for the treatment of ED in this clinical trial.

[Indexed for MEDLINE]

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