Do take it correctly

We assessed efficacy by using the responses to question 3 (frequency of penetration) and question 4 (maintenance of erections after penetration) of the 15-question International Index of Erectile Function, a validated, multidimensional, self-administered questionnaire used for the clinical assessment of erectile dysfunction and treatment outcomes in clinical studies.11 The responses to these two questions pertaining to the ability to achieve and maintain an erection sufficient for sexual intercourse, as described in the definition of erectile dysfunction,1 were rated on a scale of 1 (almost never or never) to 5 (almost always or always). A score of 0 indicated no attempt at sexual intercourse. The mean score for each of the two questions was 4.3 for 109 normal men, 31 to 86 years old, with an age distribution similar to that of the men with erectile dysfunction (unpublished data). Efficacy was also assessed on the basis of the scores for the five separate response domains of male sexual function of the International Index13: erectile function (questions 1 through 5 and 15; possible total score, 1 to 30); orgasmic function (questions 9 and 10; possible total score, 0 to 10); sexual desire (questions 11 and 12; possible total score, 2 to 10); intercourse satisfaction (questions 6, 7, and 8; possible total score, 0 to 15); and overall satisfaction (questions 13 and 14; possible total score, 2 to 10).

What special dietary instructions should I follow?

After 12 weeks of treatment in the dose-escalation study, the proportions of men taking 25, 50, or 100 mg of sildenafil were 2 percent (4 men), 23 percent (38 men), and 74 percent (121 men), respectively. For the men taking placebo, the corresponding proportions were 0 percent, 5 percent (8 men), and 95 percent (158 men). Two hundred twenty-five men who completed the 12-week study were enrolled to receive open-label sildenafil for an additional 32 weeks. In the dose–response study, increasing doses of sildenafil were associated with higher mean scores for the questions of the International Index of Erectile Function assessing frequency of penetration (question 3) and maintenance of erections after sexual penetration (question 4) (P<0.001) (Table 2). The mean scores for these questions did not vary according to the cause of erectile dysfunction.

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For question 3, the percentage increases in mean score from base line to the end of treatment were 60, 84, and 100 percent for the men who received 25, 50, and 100 mg of sildenafil, respectively, as compared with an increase of 5 percent for the men who received placebo. For question 4, the corresponding values were 121, 133, and 130 percent for the men who received 25, 50, and 100 mg of sildenafil, respectively, as compared with 24 percent for those who received placebo. In the dose-escalation study, the mean scores for questions 3 and 4 of the International Index were significantly higher after treatment for the sildenafil group than for the placebo group (P<0.001) (Table 2). The percent increase from base line was 95 percent for question 3 and 140 percent for question 4 for the men taking sildenafil, as compared with 10 percent and 13 percent, respectively, for those taking placebo. The mean scores for the erectile-function domain on the International Index increased with increasing doses of sildenafil in the dose–response study (P< 0.001).

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The mean score for the erectile-function domain in the dose-escalation study was significantly higher for the men taking sildenafil (22.1) than for those taking placebo (12.2, P<0.001) (Figure 1A). The mean scores for the orgasmic-function, intercourse-satisfaction, and overall-satisfaction domains were also significantly higher in the sildenafil group (P<0.001) (Figure 1B), whereas the mean scores for sexual desire were not significantly different in the two groups (P = 0.13). The event-log data on the proportion of men achieving erections hard enough for sexual intercourse (i.e., grade 3 or 4) during the last four weeks of treatment showed a significant dose–response relation for sildenafil (72 percent, 80 percent, and 85 percent for doses of 25 mg, 50 mg, and 100 mg, respectively, as compared with 50 percent for placebo; P<0.001). The mean number of grade 3 and grade 4 erections and the mean number of grade 4 erections during the last four weeks of treatment were also significantly higher in the sildenafil group (P< 0.001) (Figure 2A), with 80 percent of the grade 3 erections and 94 percent of the grade 4 erections resulting in successful sexual intercourse. In the dose-escalation study, 69 percent of all attempts at sexual intercourse by the men receiving sildenafil were successful in the last four weeks of treatment, as compared with 22 percent for those receiving placebo (P<0.001) (Figure 2B). The domain scores were computed by adding the scores for the individual questions in each domain. Other means of assessing efficacy were an event log, in which we asked the men to record the date and dose of medication taken, the presence of sexual stimulation, the hardness of erections (graded on a four-point scale), and whether sexual intercourse was successful, and a global-efficacy question (“Did the treatment improve your erections?”), with a response of yes or no.

• Sildenafil tablets are mainly used in adult men with erectile dysfunction.
• Regular use of sildenafil tablets requires medical supervision for safety.
• Do not use sildenafil tablets if you are allergic to any of the ingredients.

The end points of the International Index quantified the magnitude of the response, and the global-efficacy question and the event log provided qualitative assessments of efficacy. Physical examinations and standard blood-chemistry and hematologic laboratory tests were performed throughout the studies. Adverse effects were recorded by the investigators.

In this double-blind, placebo-controlled, fixed-dose study, 532 men were randomly assigned to take placebo or 25, 50, or 100 mg of sildenafil (approximately one hour before planned sexual activity but not more than once daily) for 24 weeks. Each dose consisted of three tablets from the same row of a blister pack (placebo–placebo–placebo; placebo–placebo–25 mg; placebo–placebo–50 mg; or placebo–50 mg–50 mg). The men were instructed not to consume more than two alcoholic drinks within one hour of sexual activity. Each man completed the International Index of Erectile Function at 0, 12, and 24 weeks and was asked about global efficacy at 12 and 24 weeks. The event logs were reviewed at 0, 2, 4, 8, 12, 16, 20, and 24 weeks. In the flexible dose-escalation study, 329 different men were randomly assigned to take placebo or 50 mg of sildenafil approximately one hour before sexual activity for 12 weeks.

Mechanism of action

We assessed efficacy by using the responses to question 3 (frequency of penetration) and question 4 (maintenance of erections after penetration) of the 15-question International Index of Erectile Function, a validated, multidimensional, self-administered questionnaire used for the clinical assessment of erectile dysfunction and treatment outcomes in clinical studies.11 The responses to these two questions pertaining to the ability to achieve and maintain an erection sufficient for sexual intercourse, as described in the definition of erectile dysfunction,1 were rated on a scale of 1 (almost never or never) to 5 (almost always or always). A score of 0 indicated no attempt at sexual intercourse. The mean score for each of the two questions was 4.3 for 109 normal men, 31 to 86 years old, with an age distribution similar to that of the men with erectile dysfunction (unpublished data). Efficacy was also assessed on the basis of the scores for the five separate response domains of male sexual function of the International Index13: erectile function (questions 1 through 5 and 15; possible total score, 1 to 30); orgasmic function (questions 9 and 10; possible total score, 0 to 10); sexual desire (questions 11 and 12; possible total score, 2 to 10); intercourse satisfaction (questions 6, 7, and 8; possible total score, 0 to 15); and overall satisfaction (questions 13 and 14; possible total score, 2 to 10). The domain scores were computed by adding the scores for the individual questions in each domain.

Revatio Tablets

Other means of assessing efficacy were an event log, in which we asked the men to record the date and dose of medication taken, the presence of sexual stimulation, the hardness of erections (graded on a four-point scale), and whether sexual intercourse was successful, and a global-efficacy question (“Did the treatment improve your erections?”), with a response of yes or no. The end points of the International Index quantified the magnitude of the response, and the global-efficacy question and the event log provided qualitative assessments of efficacy. Physical examinations and standard blood-chemistry and hematologic laboratory tests were performed throughout the studies. Adverse effects were recorded by the investigators. In this double-blind, placebo-controlled, fixed-dose study, 532 men were randomly assigned to take placebo or 25, 50, or 100 mg of sildenafil (approximately one hour before planned sexual activity but not more than once daily) for 24 weeks.

Incidence not known

Each dose consisted of three tablets from the same row of a blister pack (placebo–placebo–placebo; placebo–placebo–25 mg; placebo–placebo–50 mg; or placebo–50 mg–50 mg). The men were instructed not to consume more than two alcoholic drinks within one hour of sexual activity. Each man completed the International Index of Erectile Function at 0, 12, and 24 weeks and was asked about global efficacy at 12 and 24 weeks. The event logs were reviewed at 0, 2, 4, 8, 12, 16, 20, and 24 weeks. In the flexible dose-escalation study, 329 different men were randomly assigned to take placebo or 50 mg of sildenafil approximately one hour before sexual activity for 12 weeks. At each follow-up visit, the dose could be doubled or reduced by 50 percent on the basis of the therapeutic response and adverse effects.

Overdose/Missed Dose

During the last four weeks of treatment, the mean numbers of attempts at sexual intercourse that were successful were 5.9 for men in the sildenafil group and 1.5 for men in the placebo group (P<0.001) (Figure 2B). After 24 weeks of treatment in the dose–response study, improved erections were reported by 56, 77, and 84 percent of the men taking 25, 50, and 100 mg of sildenafil, respectively, as compared with 25 percent of those taking placebo (P<0.001 for treatment effect). After 12 weeks of treatment in the dose-escalation study, 101 of the 136 men in the sildenafil group who responded to the global-efficacy question (74 percent) reported improved erections, as compared with 23 of the 118 men in the placebo group who responded to the question (19 percent, P<0.001). During the dose–response study, 31 of the 316 men in the sildenafil group (10 percent) and 36 of the 216 men in the placebo group (17 percent) discontinued treatment (Table 3).

What should I tell my healthcare provider before taking sildenafil?

Each man completed the International Index of Erectile Function at 0 and 12 weeks and was asked about global efficacy at week 12. The event logs were reviewed at 0, 2, 4, 8, and 12 weeks. The men who completed the study and who did not have any serious adverse effects were eligible to receive open-label sildenafil for an additional 32 weeks. The mean frequency of responses to questions 3 and 4 of the International Index of Erectile Function for each treatment group was calculated. An analysis-of-covariance model was fitted for each question, which included main-effect terms for investigational center and treatment effect (as ordered categorical variables), with base-line score, patient age, smoking, and duration and cause of erectile dysfunction as covariates. Mean domain scores from the International buy sildenafil uk Index were calculated, and the treatment effect was analyzed by using the analysis-of-covariance model described above. From the event log, the mean numbers of grade 3 and grade 4 erections (in the dose–response study) or the percentage of attempts at sexual intercourse that were successful (in the dose-escalation study) was calculated. Analysis of covariance (dose–response study), with adjustment for the covariates listed above, or a chi-square test (dose-escalation study) was used to determine the association between the treatment groups. The answers of each treatment group to the global-efficacy question (yes or no) were analyzed with the use of logistic-regression analysis, accounting for the same covariates as those listed for the analysis-of-covariance models.

• Sildenafil tablets typically start working within 30 to 60 minutes after ingestion.
• The effects of sildenafil tablets can last up to 4-6 hours.
• Taking sildenafil with high-fat meals may delay its effectiveness.

Intention-to-treat analyses were performed on all variables and included all the men who were randomly assigned to treatment (and received treatment) and who had any assessments after base line, regardless of protocol deviations or whether the men completed the study. The base-line characteristics of the men with erectile dysfunction enrolled in each study were similar, but there were differences between the studies (Table 1).

12.1 Mechanism of Action

The men in the dose–response study had had erectile dysfunction for longer periods, and fewer of them had organic erectile dysfunction. Among the 532 men in the dose–response study, 465 (87 percent) completed the 24-week study (285 of 316 in the sildenafil group and 180 of 216 in the placebo group). Among the 329 men in the dose-escalation study, 307 (93 percent) completed the 12-week study (154 of 163 in the sildenafil group and 153 of 166 in the placebo group).

Side Effects

At each follow-up visit, the dose could be doubled or reduced by 50 percent on the basis of the therapeutic response and adverse effects. Each man completed the International Index of Erectile Function at 0 and 12 weeks and was asked about global efficacy at week 12. The event logs were reviewed at 0, 2, 4, 8, and 12 weeks. The men who completed the study and who did not have any serious adverse effects were eligible to receive open-label sildenafil for an additional 32 weeks. The mean frequency of responses to questions 3 and 4 of the International Index of Erectile Function for each treatment group was calculated.

Sildenafil side effects

An analysis-of-covariance model was fitted for each question, which included main-effect terms for investigational center and treatment effect (as ordered categorical variables), with base-line score, patient age, smoking, and duration and cause of erectile dysfunction as covariates. Mean domain scores from the International buy sildenafil uk Index were calculated, and the treatment effect was analyzed by using the analysis-of-covariance model described above. From the event log, the mean numbers of grade 3 and grade 4 erections (in the dose–response study) or the percentage of attempts at sexual intercourse that were successful (in the dose-escalation study) was calculated. Analysis of covariance (dose–response study), with adjustment for the covariates listed above, or a chi-square test (dose-escalation study) was used to determine the association between the treatment groups. The answers of each treatment group to the global-efficacy question (yes or no) were analyzed with the use of logistic-regression analysis, accounting for the same covariates as those listed for the analysis-of-covariance models.

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Intention-to-treat analyses were performed on all variables and included all the men who were randomly assigned to treatment (and received treatment) and who had any assessments after base line, regardless of protocol deviations or whether the men completed the study. The base-line characteristics of the men with erectile dysfunction enrolled in each study were similar, but there were differences between the studies (Table 1). The men in the dose–response study had had erectile dysfunction for longer periods, and fewer of them had organic erectile dysfunction. Among the 532 men in the dose–response study, 465 (87 percent) completed the 24-week study (285 of 316 in the sildenafil group and 180 of 216 in the placebo group). Among the 329 men in the dose-escalation study, 307 (93 percent) completed the 12-week study (154 of 163 in the sildenafil group and 153 of 166 in the placebo group). After 12 weeks of treatment in the dose-escalation study, the proportions of men taking 25, 50, or 100 mg of sildenafil were 2 percent (4 men), 23 percent (38 men), and 74 percent (121 men), respectively. For the men taking placebo, the corresponding proportions were 0 percent, 5 percent (8 men), and 95 percent (158 men). Two hundred twenty-five men who completed the 12-week study were enrolled to receive open-label sildenafil for an additional 32 weeks. In the dose–response study, increasing doses of sildenafil were associated with higher mean scores for the questions of the International Index of Erectile Function assessing frequency of penetration (question 3) and maintenance of erections after sexual penetration (question 4) (P<0.001) (Table 2). The mean scores for these questions did not vary according to the cause of erectile dysfunction. For question 3, the percentage increases in mean score from base line to the end of treatment were 60, 84, and 100 percent for the men who received 25, 50, and 100 mg of sildenafil, respectively, as compared with an increase of 5 percent for the men who received placebo.

• Use caution when driving or operating machinery after taking sildenafil tablets.
• Avoid excessive alcohol consumption when using sildenafil tablets, as it can increase side effects.
• Consult your doctor before taking sildenafil if you have heart issues or low blood pressure.

For question 4, the corresponding values were 121, 133, and 130 percent for the men who received 25, 50, and 100 mg of sildenafil, respectively, as compared with 24 percent for those who received placebo. In the dose-escalation study, the mean scores for questions 3 and 4 of the International Index were significantly higher after treatment for the sildenafil group than for the placebo group (P<0.001) (Table 2). The percent increase from base line was 95 percent for question 3 and 140 percent for question 4 for the men taking sildenafil, as compared with 10 percent and 13 percent, respectively, for those taking placebo. The mean scores for the erectile-function domain on the International Index increased with increasing doses of sildenafil in the dose–response study (P< 0.001).

The mean score for the erectile-function domain in the dose-escalation study was significantly higher for the men taking sildenafil (22.1) than for those taking placebo (12.2, P<0.001) (Figure 1A). The mean scores for the orgasmic-function, intercourse-satisfaction, and overall-satisfaction domains were also significantly higher in the sildenafil group (P<0.001) (Figure 1B), whereas the mean scores for sexual desire were not significantly different in the two groups (P = 0.13). The event-log data on the proportion of men achieving erections hard enough for sexual intercourse (i.e., grade 3 or 4) during the last four weeks of treatment showed a significant dose–response relation for sildenafil (72 percent, 80 percent, and 85 percent for doses of 25 mg, 50 mg, and 100 mg, respectively, as compared with 50 percent for placebo; P<0.001).

The mean number of grade 3 and grade 4 erections and the mean number of grade 4 erections during the last four weeks of treatment were also significantly higher in the sildenafil group (P< 0.001) (Figure 2A), with 80 percent of the grade 3 erections and 94 percent of the grade 4 erections resulting in successful sexual intercourse. In the dose-escalation study, 69 percent of all attempts at sexual intercourse by the men receiving sildenafil were successful in the last four weeks of treatment, as compared with 22 percent for those receiving placebo (P<0.001) (Figure 2B). During the last four weeks of treatment, the mean numbers of attempts at sexual intercourse that were successful were 5.9 for men in the sildenafil group and 1.5 for men in the placebo group (P<0.001) (Figure 2B).

• Do not take more than the prescribed dose of sildenafil tablets to avoid adverse effects.
• Limit fluid intake before and after taking sildenafil to prevent dehydration.
• Sildenafil tablets are not recommended for use in women or children.

After 24 weeks of treatment in the dose–response study, improved erections were reported by 56, 77, and 84 percent of the men taking 25, 50, and 100 mg of sildenafil, respectively, as compared with 25 percent of those taking placebo (P<0.001 for treatment effect). After 12 weeks of treatment in the dose-escalation study, 101 of the 136 men in the sildenafil group who responded to the global-efficacy question (74 percent) reported improved erections, as compared with 23 of the 118 men in the placebo group who responded to the question (19 percent, P<0.001). During the dose–response study, 31 of the 316 men in the sildenafil group (10 percent) and 36 of the 216 men in the placebo group (17 percent) discontinued treatment (Table 3).