How does the efficacy of tadalafil compare to sildenafil citrate and vardenafil HCl?

No blinded, head-to-head efficacy comparisons  of the three PDE5 inhibitors have been published  in peer-reviewed journal articles. However,  because their mechanism of action is  similar, there is no reason to assume there  will be any significant differences in ED efficacy  for the first several hours following dosing  of all three PDE5 inhibitors [35]. The  efficacy results from sildenafil citrate, tadalafil,  and vardenafil HCl trials seem to be generally  similar when the same statistical  analysis methods are used.

Clinicians should  Supplement  Vol. 2, No. 1, pp. 141–157, March 2005 147  note that ED therapy trials may vary regarding  the population of men studied, severity of ED,  presence of comorbid illnesses, first time therapy  with a PDE5 inhibitor (‘‘PDE5 inhibitor  naэЁve’’), and previous success or failure with  another PDE5 inhibitor, or other ED therapy.  Comparison of study data from separate studies  enrolling different populations is inherently  speculative and can lead to erroneous  conclusions. Nevertheless, all three PDE5 inhibitors  have been extensively studied across  broad populations of men with ED of varied  etiology and functional severity, and have  been shown to improve erectile function in  the majority of such men.