A review of oral phosphodiesterase-5 inhibitors

This review evaluated the use of oral phosphodiesterase-5 (PDE-5) inhibitors for men with erectile dysfunction.

Erectile dysfunction (ED) is one of the most common medical problems among men. ED may have a dramatic impact on the quality of life of men and their partners.

PDE-5 inhibitors are the first-choice treatments for men with ED. Common PDE-5 inhibitors include sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis). PDE-5 inhibitors relax smooth muscles, causing the dilation (widening) of blood vessels and penile erection. Despite their routine use, direct comparisons between different PDE-5 inhibitors have been limited. 

This meta-analysis (an analysis of data from several similar trials) reviewed 130 trials investigating the use of oral PDE5 inhibitors.

PDE-5 inhibitors were significantly more effective than a placebo (substance with no effect on the body) in treating ED. Improved erections were reported by 67% to 89% of men treated with PDE-5 inhibitors. This was significantly more than among those treated with a placebo (27% to 35% of men).  69% of men receiving PDE-5 inhibitors reported successful sexual intercourse, compared to only 35% receiving a placebo.

PDE-5 inhibitors were also associated with an increased risk of adverse (negative) effects. The most commonly reported adverse effects were headache, flushing and indigestion. These were reported by 24% to 35% of men receiving PDE-5 inhibitors. Severe side effects were reported among less than 2% of men treated.

Four studies provided a direct comparison of sildenafil, vardenafil, and tadalafil. Both erectile function and the risk of adverse effects were similar among the three PDE-5 inhibitors.

The researchers concluded that oral PDE-5 inhibitors significantly improved erectile function. The study also concluded that different PDE-5 inhibitors have similar effectiveness and safety profiles.