Erectile dysfunction (ED) affects up to 50% of men, between 40 and 70 years of age. In the first major trial of
sildenafil in ED, at 24 weeks, improved erections were reported by 77 and 84% of men taking
sildenafil 50 and 100mg, respectively. Subsequently,
sildenafil has been reported to be effective in men with ED associated with diabetes and
prostate cancer, and in psychogenic ED.
Sildenafil is safe in men with
coronary artery disease, provided it is not used with the
nitrates (a
contraindication). The most commonly reported adverse effects with
sildenafil are
headache,
flushing and
dyspepsia.
Vardenafil is more potent and more selective than
sildenafil at inhibiting
phosphodiesterase-5.
Vardenafil is similarly effective to
sildenafil in the treatment of ED. The only advantage that
vardenafil has over
sildenafil is that it does not inhibit phosphodiesterase-6 to alter colour perception, a rare side effect which sometimes occurs with
sildenafil.
Tadalafil has a longer duration of action than
sildenafil and
vardenafil.
Tadalafil is similarly effective as
sildenafil in the treatment of ED. In comparison studies,
tadalafil is preferred to
sildenafil (50/100mg) by men with ED, possibly because of its longer duration of action. Of the
phosphodiesterase inhibitors,
tadalafil may displace
sildenafil as the
drug of choice among men with ED.