Duration of Action of Sildenafil Citrate in Men with Erectile Dysfunction

Abstract

Introduction Viagra® (sildenafil citrate) has a rapid onset of action for the treatment of erectile dysfunction (ED). However, its duration of action has not been thoroughly investigated. Practical knowledge of the time window available for sexual intercourse would be valuable for couples planning sexual activity. Aim We investigated the duration of action of sildenafil in men with ED. Methods This was a double-blind, randomized, placebo-controlled, four-way crossover study of 16 men, mean age of 55 years (range, 36–68 years) with ED of no known organic cause. Participants received oral sildenafil (100 mg) or placebo 1, 8, or 12 hours before visual sexual stimulation (VSS). Measurements included the duration of erections of ≥ 60% rigidity, assessed by penile plethysmography (RigiScan®), and the proportion of sildenafil responders, defined as patients with erections of ≥ 60% rigidity for ≥ 4 minutes and ≥ 50% improvement over erections achieved in their placebo arm. Self-assessed duration of grade 3 (hard enough for penetration) or grade 4 (fully hard) erections was also recorded. Results At 1, 8, and 12 hours after dosing with sildenafil, the mean duration of erections with ≥ 60% rigidity was 26, 11, and 8 minutes, respectively, compared with only 3 minutes after placebo dosing (P < 0.05). However, the mean duration of self-assessed erections was 33, 23, and 16 minutes, respectively, compared with 7 minutes after placebo dosing (P < 0.05), and was greater than that assessed by RigiScan. Of the 69% sildenafil responders at 1 hour, 82% responded at 8 hours and 45% responded at 12 hours after sildenafil administration. Conclusion Sildenafil improved objective and self-assessed erectile function in men with ED, and the duration of action of sildenafil was longer than that previously reported. These data suggest that sildenafil may be effective in a significant proportion of men with ED up to 12 hours after being taken.

Are consecutive nightly recordings required for valid evaluation of sleep-associated erections?

“…In our study, we defined 'functional erection' as a score of X70% for the rigidity lasting for a minimum of 10 min on the penile tip recording, whereas Gingell used 60% rigidity for 4or ¼ 4 min to define adequate response to sildenafil. 10 The findings of our current study demonstrated that the required information for establishing the diagnosis of organic versus psychogenic ED was obtained during the first night in more than half of the participants. Patients who failed to have normal erection during the first night also failed to have normal erection during the second night.…”

Sildenafil citrate efficacy 8 h postdose in men with mild to moderate erectile dysfunction

“…In a randomized, double-blind, placebo-controlled, four-way, crossover trial of single doses in 16 men with ED, efficacy was documented by penile plethysmography (RigiScan; Dacomed Corporation, Minneapolis, MN, USA) and self-assessment after taking sildenafil 100 mg or placebo and receiving visual sexual stimulation. 7 On the basis of intrapatient comparisons of responses at each time point, the duration of erections suitable for intercourse was significantly longer 8 and 12 h postdose with sildenafil than with placebo. 7 Of the men who responded to sildenafil 1 h after administration (defined as erections of X60% rigidity for X4 min and X50% improvement over erections achieved when on placebo), 82% responded at 8 h and 45% The 4-h time frame estimated previously for sildenafil activity was deduced from the drug's terminal elimination half-life (t 1/2 ) and the time to maximum plasma concentration.…”

“…7 On the basis of intrapatient comparisons of responses at each time point, the duration of erections suitable for intercourse was significantly longer 8 and 12 h postdose with sildenafil than with placebo. 7 Of the men who responded to sildenafil 1 h after administration (defined as erections of X60% rigidity for X4 min and X50% improvement over erections achieved when on placebo), 82% responded at 8 h and 45% The 4-h time frame estimated previously for sildenafil activity was deduced from the drug's terminal elimination half-life (t 1/2 ) and the time to maximum plasma concentration. The sildenafil t 1/2 (3-6 h 9 ) is similar to that of vardenail (Levitra; Bayer Pharmaceuticals Corporation, West Haven, CT, USA; t 1/2 ¼ 4-5 h) 20 and shorter than that of tadalafil (Cialis; Lilly ICOS LLC, Indianapolis, IN, USA; t 1/2 ¼ 17.5 h).…”

“…6 In men with ED, empirical observations and the results of clinical trials suggest that the duration of sildenafil activity may be much longer than the 4-5 h currently described in the manufacturer's prescribing information. 7,8 The 4-5 h duration of activity for sildenafil on erectile response was inferred from its pharmacokinetic characteristics (that is, the achievement of maximum plasma concentrations within 1 h and a terminal elimination half-life of between 3 and 6 h). 9 However, previously published clinical trial results support a longer duration of activity.…”

Sildenafil citrate (Viagra) treatment for erectile dysfunction: an updated profile of response and effectiveness

“…19 In a double-blind, placebo-controlled, 4-way crossover trial in 17 men with ED, in which visual sexual stimulation was provided 1 h after dosing, grade 3 or 4 erections lasted nearly five times longer after administration of sildenafil 100 mg compared with placebo (33 vs 7 min, Po0.05). 20 A pooled analysis of 26 double-blind, placebocontrolled sildenafil trials conducted from 1996 to 2003, which included data from 3251 men with ED randomized to sildenafil and 2875 randomized to placebo, demonstrated significant (Po0.0001) improvements from baseline to the end of treatment in scores for the frequency of erections hard enough for penetration (IIEF Q2), the frequency of satisfactory sexual intercourse (IIEF Q7), the degree of enjoyment of sexual intercourse (IIEF Q8), and satisfaction with overall sex life (IIEF Q13) and sexual relationship (IIEF Q14). 21 Moreover, the improvement in frequency of erections hard enough for penetration (IIEF Q2) correlated positively and significantly (Po0.0001) with the improvements in these IIIEF measures of sexual satisfaction and enjoyment (range of r ¼ 0.51-0.68).…”