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How to Evaluate the Efficacy of the Phosphodiesterase Type 5 Inhibitors


Emmanuele A. Jannini, MD, Course of Endocrinology and Medical Sexology, Department of Experimental Medicine, University of L'Aquila, Coppito, Blg 2, Room A2/54, L'Aquila 67100, Italy. Tel: +39 0862433530; Fax: +39 0862433523; E-mail:


Introduction.  Several methods have been so far proposed to compare the effectiveness of the three available phosphodiesterase type 5 inhibitors (PDE5Is).

Methods.  Two urologists (E.C. and G.B.B.), together with the Controversy's Editor (E.A.J.), with expertise in the area of medical treatment of erectile dysfunction (ED) present the various perspectives on the evaluation of PDE5Is in ED. The use of the most popular psychometric tool, the International Index of Erectile Function, is presented by an expert psychologist (L.R.D.).

Main Outcome Measures.  Expert opinion supported by the critical review of the currently available literature.

Results.  Trials have demonstrated that the PDE5Is are excellent drugs with a great specificity of action and an almost perfect tolerance profile. Some instruments for comparison of clinical efficacy have to be considered subjective (psychometry, patient's preference, changes in quality of general, or sexual life). Some others are more objective (hardness, hormonal levels, and local circulation). An evidence-based comparison of the three PDE5Is should in the future be rooted in both subjective and objective methods. This will be of paramount importance in the drug trial design of new, forthcoming PDE5Is.

Conclusions.  Comparison between PDE5Is using both subjective and objective parameters will permit to individuate, on the basis of the evidence, the subset of couples where one drug, or one dose, or dose regimen, is to be considered of first choice. Jannini EA, DeRogatis LR, Chung E, and Brock GB. How to evaluate the efficacy of the phosphodiesterase type 5 inhibitors. J Sex Med 2012;9:26–33.