Effectiveness of sildenafil citrate (Viagra) and tadalafil (Cialis) on sexual responses in Saudi men with erectile dysfunction in routine clinical practice

Pak J Pharm Sci. 2008 Jul;21(3):275-81.

Abstract

Satisfaction with the sexual experience is considered important when evaluating the impact of treatments for erectile dysfunction, yet enhanced satisfaction has been infrequently assessed in the sexual trials. We evaluated the efficacy of sildenafil vs. tadalafil, in Saudi men with erectile dysfunction and determined the self-based rating of medicinal preference. Sildenafil citrate (Viagra) is a potent inhibitor of the electrolytic enzyme type V phosphodiesterase (PDE5), in the corpus cavernosum and therefore increases the penile response to sexual stimulation. Tadalafil (Cialis) is also a PDE5 inhibitor that increases the level of cyclic guanosine monophosphate (cGMP) in cavernous smooth muscle cells. Whereas cGMP is a second messenger for the vasodilator effects of nitric oxide causing smooth muscle relaxation, which in turn leads to penile erection; however the mechanism by which cGMP stimulates relaxation of the smooth muscles remains to be elucidated. Both sildenafil and tadalafil have a rapid onset with the effectiveness up to 4 hours and 36 hours respectively. In this study subjects treated with 100 mg oral dose of sildenafil / 20 mg tadalafil were found to be associated with higher mean scores for the questions of the International Index of Erectile Function (IIEF). Frequency of penetration and maintenance of erection after sexual penetration and/or during masturbation were found to be enhanced significantly (p<0.001) in both sildenafil/tadalafil treated men. Similarly mean domain of erectile function, orgasmic function, and intercourse satisfaction also showed a significantly positive improvement (p/0.001) in both the treated groups in comparison with their age matched untreated controls. Interestingly in all the cases, tadalafil group showed considerably greater positive responses than the sildenafil group but within the same significant levels. Strikingly the sexual-desire domain in sildenafil treated men with respect to their aged matched controls showed a non-significant difference, where as this difference was found to be highly significant in tadalafil treated group. Similarly mean scores for the overall satisfaction domains of the IIEF in comparison with the untreated subjects showed a significant positive response in the sildenafil treated group (p<0.001), where as tadalafil treated group showed a highly significant positive response (p<0.005). These findings suggest that both sildenafil and tadalafil may assist an individual in extending/enhancing the excitement phase or prolonging the sexual interaction. These studies further conclude that there is a major point of difference between the short-acting agent sildenafil and the longer acting tadalafil. This probably allows more choice about the onset of sexual responses with tadalafil than with sildenafil.

Publication types

  • Comparative Study
  • Controlled Clinical Trial

MeSH terms

  • Administration, Oral
  • Adult
  • Carbolines / administration & dosage
  • Carbolines / therapeutic use*
  • Coitus
  • Erectile Dysfunction / drug therapy*
  • Erectile Dysfunction / physiopathology
  • Humans
  • Male
  • Middle Aged
  • Orgasm / drug effects
  • Patient Satisfaction
  • Penile Erection / drug effects
  • Phosphodiesterase Inhibitors / administration & dosage
  • Phosphodiesterase Inhibitors / therapeutic use*
  • Piperazines / administration & dosage
  • Piperazines / therapeutic use*
  • Purines / administration & dosage
  • Purines / therapeutic use
  • Saudi Arabia
  • Sildenafil Citrate
  • Sulfones / administration & dosage
  • Sulfones / therapeutic use*
  • Surveys and Questionnaires
  • Tadalafil
  • Treatment Outcome

Substances

  • Carbolines
  • Phosphodiesterase Inhibitors
  • Piperazines
  • Purines
  • Sulfones
  • Tadalafil
  • Sildenafil Citrate