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CONTEXT: Erectile dysfunction is common in men with diabetes. OBJECTIVE: To assess the efficacy and safety of oral sildenafil citrate in the treatment of erectile dysfunction in men with diabetes. DESIGN: A multicenter, randomized, double-blind, placebo-controlled, flexible dose-escalation study conducted May through November 1996. SETTING: Patients' homes and 19 clinical practice centers in the United States. PATIENTS: A total of 268 men (mean age, 57 years) with erectile dysfunction (mean duration, 5.6 years) and diabetes (mean duration, 12 years). INTERVENTIONS: Patients were randomized to receive sildenafil (n = 136) or placebo (n = 132) as needed, but not more than once daily, for 12 weeks. Patients took the study drug or placebo 1 hour before anticipated sexual activity. The starting dose of sildenafil citrate was 50 mg, with the option to adjust the dose to 100 mg or 25 mg based on efficacy and tolerability, to be taken as needed. MAIN OUTCOME MEASURES: Self-reported ability to achieve and maintain an erection for sexual intercourse according to the International Index of Erectile Function and adverse events. RESULTS: Two hundred fifty-two patients (94%) completed the study (131/136 in the sildenafil group, 121/132 in the placebo group). By intention-to-treat analysis, at 12 weeks, 74 (56%) of 131 patients in the sildenafil group reported improved erections compared with 13 (10%) of 127 patients in the placebo group (P<.001). The proportion of men with at least 1 successful attempt at sexual intercourse was 61 % (71/ 117) for the sildenafil group vs 22% (25/114) for the placebo group (P<.001). Adverse events related to treatment were reported for 22 (16%) of 136 patients taking sildenafil and 1 (1%) of 132 patients receiving placebo. The most common adverse events were headache (11% sildenafil, 2% placebo), dyspepsia (9% sildenafil, 0% placebo), and respiratory tract disorder (6% sildenafil, 2% placebo), predominantly sinus congestion or drainage. The incidence of cardiovascular adverse events was comparable for both groups (3% sildenafil, 5% placebo). CONCLUSION: Oral sildenafil is an effective and well-tolerated treatment for erectile dysfunction in men with diabetes.

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Sildenafil citrate has been shown to be effective in a wide range of patients with erectile dysfunction and has been approved in the United States for this indication. The overall clinical safety of oral sildenafil, a potent inhibitor of phosphodiesterase type 5, in the treatment of erectile dysfunction was evaluated in more than 3700 patients (with a total of 1631 years of exposure worldwide). Safety and tolerability data were analysed from a series of double-blind, placebo-controlled studies and from 10 open-label extension studies of sildenafil in the treatment of erectile dysfunction. A total of 4274 patients (2722 sildenafil, 1552 placebo; age range 19-87 y) received double-blind treatment over a period of up to six months' duration, and 2199 received long-term, open-label sildenafil for up to 1 y. The most commonly reported adverse events (all causes) were headache (16% sildenafil, 4% placebo), flushing (10% sildenafil, 1% placebo), and dyspepsia (7% sildenafil, 2% placebo) and they were predominantly transient and mild or moderate in nature. These adverse events reflect the pharmacology of sildenafil as a phosphodiesterase type 5 inhibitor. No cases of priapism were reported. The rate of discontinuation due to adverse events (all causes) was comparable for patients treated with sildenafil (2.5%) and placebo (2.3%). In open-label extension studies, 90% of patients completed long-term sildenafil treatment, with only 2% withdrawing due to adverse events. Sildenafil is a well-tolerated oral treatment for erectile dysfunction.

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BACKGROUND: Sildenafil is a potent inhibitor of cyclic guanosine monophosphate hydrolysis [corrected] in the corpus cavernosum and therefore increases the penile response to sexual stimulation. We evaluated the efficacy and safety of sildenafil, administered as needed in two sequential double-blind studies of men with erectile dysfunction of organic, psychogenic, and mixed causes. METHODS: In a 24-week dose-response study, 532 men were treated with oral sildenafil (25, 50, or 100 mg) or placebo. In a 12-week, flexible dose-escalation study, 329 different men were treated with sildenafil or placebo, with dose escalation to 100 mg based on efficacy and tolerance. After this dose-escalation study, 225 of the 329 men entered a 32-week, open-label extension study. We assessed efficacy according to the International Index of Erectile Function, a patient log, and a global-efficacy question. RESULTS: In the dose-response study, increasing doses of sildenafil were associated with improved erectile function (P values for increases in scores for questions about achieving and maintaining erections were <0.001). For the men receiving 100 mg of sildenafil, the mean score for the question about achieving erections was 100 percent higher after treatment than at base line (4.0 vs. 2.0 of a possible score of 5). In the last four weeks of treatment in the dose-escalation study, 69 percent of all attempts at sexual intercourse were successful for the men receiving sildenafil, as compared with 22 percent for those receiving placebo (P<0.001). The mean numbers of successful attempts per month were 5.9 for the men receiving sildenafil and 1.5 for those receiving placebo (P<0.001). Headache, flushing, and dyspepsia were the most common adverse effects in the dose-escalation study, occurring in 6 percent to 18 percent of the men. Ninety-two percent of the men completed the 32-week extension study. CONCLUSIONS: Oral sildenafil is an effective, well-tolerated treatment for men with erectile dysfunction.

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The efficacy and safety of oral sildenafil citrate for the treatment of erectile dysfunction (ED) were assessed in a 12-week placebo-controlled study. Men with ED of organic, psychogenic, or mixed aetiology were randomised to placebo (n = 166) or 50 mg sildenafil (n = 163), with adjustment to 100 mg or 25 mg based on efficacy and tolerability. Efficacy assessments included a global efficacy question, event log data, and an optional partner questionnaire. At the end of the study, improved erections were reported by 74% of patients receiving sildenafil versus 16% for placebo (p < 0.0001). In the final 4 weeks of treatment, 65% of all attempts at sexual intercourse were successful for all patients (responders and non-responders) receiving sildenafil versus 20% for placebo (p < 0.001). The mean number of successful attempts per month was 5.9 for patients receiving sildenafil versus 1.5 for those receiving placebo (p < 0.0001). The most common adverse events--headache, flushing, and dyspepsia--were generally mild to moderate in nature and rarely (< 1%) a reason for discontinuation of treatment. Oral sildenafil is an effective, reliable and well-tolerated treatment for ED of organic, psychogenic or mixed aetiology.

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Although fully explored in larger animals, the role of injection site and sample microsphere content on variability of coronary blood flow (CBF) measurement using the microsphere technique remains controversial in rats despite the fact that this species is extensively used in cardiovascular research. We therefore investigated these variables in two studies. In a first study, we established that the precision of the method, assessed by the variability of four simultaneous CBF determinations, was a function of the sample microsphere number. Coefficient of variation (CV) averaged 4-10% when the tissue and reference samples received greater than 1000 and greater than 100 spheres, respectively, and did not improve appreciably with larger numbers of microspheres. In a second study, flow CV was measured following left atrial (LA) or left ventricular (LV) microsphere injections performed nearly simultaneously in the same conscious animal or in two similar groups of animals. CBF variability was lower by 22-62% after LA than after LV injections. Estimates obtained from separate analysis of the main variability components indicated that, with one exception, the variability associated with LV injections was at least 1.4 to 2.8 times higher than that due to LA injections. These findings establish the minimum number of microspheres needed to obtain precise blood flow determinations in the rat model and confirm previous reports, in anaesthetised rats, that LA microsphere injections generally yield more precise coronary blood flow determinations than LV injections.

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