Long-term efficacy and safety of oral Viagra® (sildenafil citrate) in men with erectile dysfunction and the effect of randomised treatment withdrawal

The long-term efficacy and safety of oral Viagra® (sildenafil citrate), a selective phosphodiesterase 5 inhibitor, and the effect of withdrawing treatment were evaluated in men with erectile dysfunction (ED). In 233 men with ED of psychogenic or mixed organic/psychogenic aetiology, 16 weeks of open-label, flexible-dose sildenafil treatment (10–100 mg) was followed by eight weeks of double-blind, fixed-dose, randomised withdrawal to placebo or continued treatment with sildenafil. Sildenafil was taken as needed (not more than once daily) approximately 1 h prior to sexual activity. The main outcome measures were a global efficacy question, a sexual function questionnaire, an event log of erections, and adverse event recording. In the open-label phase, 200 of 216 patients (93%) reported improved erections with sildenafil; 28 patients (12%) discontinued treatment. In the double-blind phase, the significant improvements in the frequency and duration of erections were maintained in the sildenafil group but returned to pre-treatment values in patients on placebo (P values<0.0001 versus placebo). The most frequent adverse events in the sildenafil group during the double-blind phase were flushing (7%), headache (6%), and dyspepsia (5%). Of the 192 patients enrolled in the 1-y extension, 90% completed the study; only two patients (1%) were withdrawn due to lack of efficacy. In men with ED of psychogenic or mixed aetiology, oral sildenafil is effective and well-tolerated both at the initiation of therapy and during long-term treatment. For most patients, sildenafil treatment must be continued for improvements in erectile function to be maintained.