title: Phosphodiesterase 5 inhibitors in male sexual dysfunction.
abstract: OBJECTIVE
  Phosphodiesterase 5 inhibitors are preferred by most men for the oral treatment of erectile dysfunction. In many guidelines, this therapy is recommended as first-line therapy because of convenience, high efficacy, and low rates of side-effects. Sildenafil was the first drug for the treatment of erectile dysfunction, introduced in 1998. There are now two new phosphodiesterase 5 inhibitors, vardenafil and tadalafil, for which approval was recently given in the European Union and is expected this year in the United States.
  
  
  RESULTS
  Sildenafil has proved to be a very effective medicinal product. According to initial studies, vardenafil and tadalafil have demonstrated efficacy comparable to that of sildenafil. However, fewer data are available evaluating the adverse effects of vardenafil and tadalafil, particularly on their long-term use and their use in high-risk groups. Interestingly, vardenafil and tadalafil have a higher potency than sildenafil. Moreover, the long life of tadalafil has been associated with an erectogenic potential of the drug lasting for more than 24 h. The advantage of this is the possibility of a patient engaging in sexual activity more than once after a single administration of the drug.
  
  
  CONCLUSIONS
  In the future, in addition to sildenafil, the new phosphodiesterase 5 inhibitors vardenafil and tadalafil will play an important role in the management of erectile dysfunction, depending on the patient's health profile.
authors.affiliation: Department of Biochemistry, University of Fribourg, Fribourg, Switzerland. akuethe@gmx.de
authors.forename: Andrea
authors.initials: A
authors.lastname: Kuthe
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases; D002243:Carbolines / Q000009:adverse effects / Q000627:therapeutic use; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D007093:Imidazoles / Q000009:adverse effects / Q000627:therapeutic use; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D010727:Phosphoric Diester Hydrolases / Q000187:drug effects*; D010879:Piperazines / Q000009:adverse effects / Q000627:therapeutic use; D011687:Purines; D000068677:Sildenafil Citrate; D013450:Sulfones; D000068581:Tadalafil; D014227:Triazines; D000069058:Vardenafil Dihydrochloride
chemical_list: D002243:Carbolines; D007093:Imidazoles; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014227:Triazines; D000069058:Vardenafil Dihydrochloride; D000068581:Tadalafil; D000068677:Sildenafil Citrate; D010727:Phosphoric Diester Hydrolases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517381:PDE5A protein, human