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 Of the 192 patients enrolled in the 1-y extension, 90% completed the study; only two patients (1%) were withdrawn due to lack of efficacy.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.     

从更好的勃起到更好的性生活:万艾可研究进展

万艾可(枸橼酸西地那非)起效快,使患者达到和维持坚硬的勃起,已被证实为首选的勃起功能障碍(ED)治疗药物。近年来,有关万艾可疗效的研究越来越多地关注其对整体性生活的改善,即对患者心理因素的影响。通过应用心理学评价工具,如勃起功能障碍治疗满意度量表、自尊心和性关系问卷、勃起功能障碍心理影响评分等,研究发现万艾可显著改善以下心理性因素:ED患者及其伴侣对性交和性关系的满意度、患者的自信心和自尊心、与伴侣亲近和进行性交的欲望等。服用万艾可的ED患者性交尝试次数显著增加,健康相关的生活质量显著提高。因此,万艾可产生更好的勃起,进一步促进更好的性生活良性循环。     

西地那非在中国男科临床应用十年回顾

自从10年前西地那非进入中国男科临床以来,其在治疗ED方面的疗效和安全性已被证明,并为国内医生和患者所接受,对各种病因、不同程度、不同年龄的ED患者均具有良好疗效。近年来,西地那非不仅广泛应用于ED治疗上,国内相关研究还显示西地那非在治疗或联合治疗男性早泄等方面也具有一定的疗效,本文在此做一综述。     

Assessment of the efficacy of Viagra (sildenafil citrate) using the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS)

Treatment satisfaction is a predictor of long-term compliance in patients with erectile dysfunction (ED). We assessed patient satisfaction with and efficacy of Viagra (sildenafil citrate) using the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) and 3 global efficacy questions. Twenty-nine men with ED who had completed a prior study of MUSE (alprostadil) versus Caverject (alprostadil) took a 50-mg dose of Viagra 1 h preceding intercourse. Efficacy and patient satisfaction with Viagra were high. Satisfaction as measured by EDITS was highly correlated to patients' final ED treatment choice. This correlation could make EDITS useful in identifying long-term patient satisfaction, and thus of considerable clinical benefit.     

A dose-escalation study to assess the efficacy and safety of sildenafil citrate in men with erectile dysfunction

OBJECTIVE: To assess the efficacy and safety of sildenafil citrate (Viagra, Pfizer Inc., USA) in a double-blind, placebo-controlled, dose-escalation study over a period of 26 weeks in men with erectile dysfunction of a broad spectrum of aetiology. PATIENTS AND METHODS: In all, 315 patients from five countries were randomized to receive treatment with placebo (156 men) or sildenafil (159 men). Significant concomitant medical conditions were hypertension (20%), a history of pelvic surgery (19%), diabetes mellitus (15%), and ischaemic heart disease (10%). Patients randomized to treatment received a starting dose of 25 mg of sildenafil or matching placebo, which could be increased to 50 mg and then to 100 mg of sildenafil, based on efficacy and tolerability. Assessments of efficacy comprised the 15-item International Index of Erectile Function (IIEF), including question three (ability to achieve an erection) and question four (ability to maintain an erection), a partner questionnaire, an overall efficacy question, and event-log data. RESULTS: After 12 weeks of treatment, 26%, 32% and 42% of patients were taking 25, 50 and 100 mg of sildenafil, respectively. A similar distribution of doses was reported after 26 weeks of treatment. Treatment with sildenafil significantly improved the patients' abilities to achieve and maintain an erection compared with treatment with placebo (P < 0.001). Scores for four of the five sexual function domains of the IIEF (erectile function, orgasmic function, intercourse satisfaction and overall satisfaction) also improved significantly (P < 0.001). There was a significant improvement in the mean score for the erectile function domain, regardless of the aetiology of erectile dysfunction (P < 0.001). After 12 weeks and 26 weeks of treatment, 82% and 79% of patients receiving sildenafil reported improved erections, compared with 24% and 23% of patients receiving placebo, respectively (P < 0.001). Treatment-related adverse events were mild to moderate and occurred in 27% of patients receiving sildenafil, compared with 8% of patients receiving placebo. CONCLUSION: Sildenafil is an effective and well-tolerated treatment for men with erectile dysfunction of a broad spectrum of aetiology.     

Efficacy and safety of fixed-dose oral sildenafil in the treatment of erectile dysfunction of various etiologies

OBJECTIVES: To determine the efficacy and safety of fixed-dose oral sildenafil in patients with erectile dysfunction (ED) of various etiologies. METHODS: In a 12-week, double-blind, randomized, placebo-controlled, fixed-dose study, 514 men (mean age 56 years) with ED were randomized to receive 25, 50, or 100 mg of sildenafil or placebo. The primary etiology of ED was determined to be organic in 32% of men, psychogenic in 25%, or mixed in 43%. Sildenafil or placebo was taken in the home setting approximately 1 hour before sexual activity, not more than once daily. Efficacy was determined by responses to question 3 (ability to achieve an erection) and question 4 (ability to maintain an erection) of the 15-item International Index of Erectile Function (IIEF). Other measures of efficacy included the five sexual function domains of the IIEF, a global efficacy question, event log data, and a partner questionnaire. RESULTS: Sildenafil significantly increased patients' ability to achieve and maintain erections (P <0.0001), with efficacy increasing with increasing dose. Significant improvements were also observed in the IIEF domains for erectile function, orgasmic function, intercourse satisfaction, and overall sexual satisfaction (P <0.0001). The proportion of subjects who felt that treatment with sildenafil improved their erections was significantly greater (67% to 86%) than that with placebo treatment (24%, P <0.0001). The proportion of successful attempts at sexual intercourse also increased significantly with sildenafil treatment (P <0.001). Partner responses corroborated patient reports. Sildenafil was well tolerated at the three doses studied. CONCLUSIONS: Oral sildenafil is an effective, well-tolerated treatment for ED of various etiologies.     

Efficacy and safety of sildenafil citrate (Viagra) for the treatment of erectile dysfunction in men in Egypt and South Africa

The efficacy of sildenafil citrate (Viagra), an oral agent for the treatment of erectile dysfunction (ED), has been demonstrated in global studies. This 12-week randomized, double-blind, placebo-controlled, parallel-group, flexible-dose study assessed the efficacy and safety of sildenafil to treat ED in men in Egypt and South Africa. Men with ED of varied etiology were randomized to receive sildenafil 50 mg (n=128) or placebo (n=126); doses could be adjusted to 100 or 25 mg. Questions from the International Index of Erectile Function (IIEF) assessing the ability to achieve (Q3) and maintain (Q4) erections demonstrated a significant improvement with sildenafil compared with placebo (P<0.0001). Improved erections were reported by 74% of patients receiving sildenafil and 27% of those receiving placebo (P<0.0001). Headache, dyspepsia, and flushing were the most common adverse events in sildenafil-treated patients. These results are consistent with clinical trials in other countries. We conclude that sildenafil is an efficacious and well-tolerated treatment for men with ED in Egypt and South Africa.     

Clinical efficacy and safety of sildenafil citrate (Viagra) in a multi-racial population in Singapore: A retrospective study of 1520 patients

BACKGROUND: Sildenafil citrate (Viagra), a selective inhibitor of cGMP-specific phosphodiesterase type-5, has been used as an oral therapeutic drug for erectile dysfunction. The present paper is a clinical study of the success rate and side-effects of the use of sildenafil in a multi-racial population in Singapore. METHODS: From April 1999 to May 2000, 1520 patients were given sildenafil citrate. Of these, 912 patients (mean age, 54.6 years; age range, 22-99 years) were followed up and evaluated for clinical efficacy and safety of the drug. The mean duration of erectile dysfunction (ED) and follow-up periods were 31.5 and 3.0 months, respectively. RESULTS: Satisfactory erections assessed by single global efficacy question (GEQ) occurred in 83% of patients, major side-effects in the form of flushing (3.48%), headache (1.97%), blurred vision (1.25%), giddiness (1.18%), warmth (1.11%) and others (4.92%) were recorded in 127 patients (13.9%). Racially, Chinese men with ED had higher efficacy (85.7%), compared to Indian men (74.2%) and Malay men (72.8%). With respect to comorbid profiles, an efficacy of 77.8% (n = 271), 83.9% (n = 292), 86.4% (n = 44) and 83.3% (n = 199) was recorded in diabetic, hypertensive, ischemic heart disease patients and in benign prostatic hyperplasia patients, respectively. Patients who smoked (n = 135) and drank alcohol (n = 118) showed an efficacy of 80%. Baseline hormonal profiles of luteinizing hormone, follicle stimulating hormone, testosterone and prolactin did not affect the success rates of sildenafil citrate. Many patients had earlier received other forms of treatment (medicated urethral suppository for erection (MUSE; 84.9%); vacuum devices (86.8%), traditional medicines (100%) and other oral medications (89.2%)), but this did not influence the success rate of sildenafil citrate. But patients previously treated with prostaglandin-E intracavernosal injections were less successful on sildenafil citrate (77.3%). In the total cohort, 50 mg sildenafil citrate was an effective dose in 49% of patients and 46.5% patients needed 100 mg sildenafil citrate, while 4.1% of the total cohort needed only 25 mg sildenafil citrate. CONCLUSION: Oral sildenafil citrate has been shown to be an effective, safe and well tolerated drug in Singaporean men with ED, as in men from other parts of the world.     

Sildenafil citrate (Viagra) in the treatment of men with erectile dysfunction in southern Latin America: a double-blind,randomized, placebo-controlled,parallel-group,multicenter, flexible-dose escalation study

Our objectives were: (1) to determine the efficacy, safety, and tolerability of sildenafil citrate (Viagra) administered to men with broad-spectrum erectile dysfunction (ED) in southern Latin America; and (2) to correlate Rigiscan measurements assessing ED etiology with the investigator's assessment. A total of 141 men with broad-spectrum ED (mean age 57) were enrolled in a randomized, 12-week, double-blind, placebo-controlled, flexible-dose escalation study of sildenafil. After the 12-week treatment period, the mean score for the primary efficacy variables had risen significantly: for the sildenafil group, 66.2% from baseline for question 3 of the International Index of Erectile Function and 77.6% for question 4, vs 15.1% and 21.2% for the placebo group, respectively (P<0.0001). Rigiscan data confirmed investigator assessments of etiology. Headache and flushing, usually mild and transient, were the most common adverse events. Sildenafil was an effective, well-tolerated treatment for men in southern Latin America with broad-spectrum ED.     

Sildenafil citrate (Viagra) for the treatment of erectile dysfunction in Nigerian men

Fifty-eight Nigerian outpatients with documented erectile dysfunction (ED) received open-label sildenafil citrate (Viagra) for 8 weeks. The 50-mg starting dose could be adjusted to 100 or 25 mg based on response and tolerability. The International Index of Erectile Function (IIEF) Questionnaire, a global efficacy question, and intercourse data recorded in a patient event log were used to assess efficacy. Frequency of penetration and maintained erection were both significantly enhanced (P<0.0001); 95% of patients reported improved erections and 81% of all attempts at intercourse were successful. Orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction also improved significantly (P&<0.0001). The most frequent adverse events (all-cause) were headache (17%) and myalgia (3%); only one patient discontinued treatment because of headache, which was considered unrelated to sildenafil. Oral sildenafil significantly improved erectile function and was well tolerated in this trial of Nigerian men suffering from ED. Our results are consistent with reports from other countries.     

西地那非治疗勃起功能障碍的临床疗效

目的 :观察西地那非对不同年龄和病因勃起功能障碍 (ED)病人的疗效。　方法 :88例ED病人口服不同剂量的西地那非 4～ 2 2周 ,以国际勃起功能指数 5 (IIEF 5 )评分为评估标准判断疗效 ,设对照组作比较。　结果 :西地那非治疗ED病人的总疗效率为 80 .7% ,IIEF 5值上升幅度与西地那非疗效呈正相关。不同年龄ED病人的疗效无明显差异。神经性ED病人的显效率和IIEF 5值与心因性病人差异显著。　结论 :西地那非治疗ED是安全有效的 ,IIEF 5可作为评判ED疗效的可靠指标。     

Efficacy of sildenafil citrate in prostate brachytherapy patients with erectile dysfunction

Objectives. To ascertain the efficacy of sildenafil citrate (Viagra) in patients with erectile dysfunction (ED) either before or after prostate brachytherapy by an open-label, nonrandomized study.Methods. Sixty-two patients who underwent prostate brachytherapy between March 1995 and July 1998, had ED either before or after brachytherapy, and were interested in treatment with sildenafil comprised the patient population. Clinical and treatment parameters evaluated for medication efficacy included patient age at brachytherapy and at medication administration, hypertension, diabetes, smoking history, onset of ED, potency status before implant, frequency of intercourse before brachytherapy (if potent), use of neoadjuvant hormonal manipulation, use of moderate dose external beam radiation therapy before implantation, choice of isotope, V100 (the percentage of the prostate volume receiving at least 100% of the prescribed minimal peripheral dose), and sildenafil dose.Results. Fifty (80.6%) of 62 patients responded favorably to sildenafil. None of the treatment parameters predicted medication failure, and among the clinical parameters, only diabetes predicted failure (3 of 5) and only with borderline statistical validity (P = 0.046).Conclusions. Our results suggest brachytherapy-induced impotence is as amenable to sildenafil treatment as ED from other causes. In addition, our 80.6% success rate is comparable to reported results for patients who underwent bilateral nerve-sparing radical prostatectomy and significantly better than patients who underwent unilateral nerve-sparing or non-nerve-sparing approaches.     

Are adverse effects of sildenafil also caused by inhibition of diamine oxidase?

BACKGROUND: Sildenafil citrate (Viagra), a drug used to treat erectile dysfunctions, causes adverse reactions such as headache, flushing or nasal congestion. Sildanefil's potency as inhibitor of diamine oxidase was investigated, as side effects may also be induced by histamine itself due to an impaired histamine metabolism. METHODS: Placental diamine oxidase inhibition experiments were performed with consecutive dilutions of sildenafil citrate (10(-5) to 10(-9) mol/l). In 9 male volunteers in vivo diamine oxidase inhibition was investigated after taking 100 mg sildenafil (Viagra). RESULTS: Sildenafil citrate did not inhibit placental diamine oxidase either in vitro or in vivo. However, infusion of 300 mg of cimetidine inhibited diamine oxidase activity by 27 +/- 7% 15 min after infusion, demonstrating that drugs may inhibit diamine oxidase in vivo. CONCLUSION: As side effects of sildenafil are not caused due to inhibition of diamine oxidase, sildenafil citrate seems to be harmless for patients suffering from histamine intolerance.     

Evaluation of a progressive treatment program for erectile dysfunction in patients with diabetes mellitus

The aim was to evaluate the effectiveness of a progressive program, starting with simple methods and, when not effective, moving to more complex methods, to treat erectile dysfunction (ED) in patients with diabetes mellitus. A total of 284 diabetic patients with ED entered into a 6-phase program starting with sildenafil citrate (Viagra). Those with contraindications, side effects, or negative response (erection insufficient for vaginal penetration) were switched to the vacuum erection device (VED), and then progressively (for failures) to intracavernous injection (ICI), sildenafil citrate+ICI, ICI+VED, and penile prosthesis. Patients were followed for 2 y. Of the 284 patients 276 patients were eligible for sildenafil citrate and 147 (53.3%) responded positively, but 25 (9.1%) patients stopped it soon due to adverse effects. Of 162 patients (129 nonresponders, eight noneligible for the sildenafil and 25 patients who dropped out due to adverse effects), treated with VED, 114 (70.4%) responded well, however, only 19 (11.7%) patients agreed to continue its use. Of the remaining 143 patients (nonresponders, noneligible for the previously mentioned treatments and patients who dropped out due to adverse effects), 103/143 (72%) responded to ICI, 27/40 (67.5%) to sildenafil+ICI, and 9/13 (69.2%) to ICI+VED. Four patients received a penile implant. At the 2 y follow-up, 81 of 284 patients who entered the study (28.5%) were still responding to sildenafil, seven (2.5%) to VED, 113 (39.8%) to ICI, 24 (8.5%) to sildenafil+ICI, two (0.7%) to ICI+VED; 15 (5.3%) had a penile implant. In all 17 (6%) patients reported spontaneous erections, 11 (3.9%) stopped the treatment due to family reasons and 14 (4.9%) failed the treatment. In conclusion, the progressive treatment program for ED seems to be very effective for diabetic patients, yielded a complete response for short-term and 91.2% rate of success at the end of 2 y follow-up.     

Efficacy and safety of flexible-dose oral sildenafil citrate (Viagra) in the treatment of erectile dysfunction in Brazilian and Mexican men

A 12-week, double-blind, placebo-controlled, multicenter study evaluated the efficacy and safety of flexible-dose sildenafil citrate (Viagra) treatment (25, 50 or 100 mg) in Brazilian and Mexican men with erectile dysfunction (ED) of broad-spectrum etiology. Efficacy was assessed on the basis of responses to the 15-item International Index of Erectile Function (IIEF) questionnaire, completed at baseline and after 12 weeks of treatment. At end point, mean scores for all IIEF domains of sexual function (erectile function, orgasmic function, sexual desire, intercourse satisfaction and overall satisfaction) were significantly (P<0.0001) higher in the sildenafil group (n=109) than in the placebo group (n=105). These findings confirm the significant increases in frequency of penetration and frequency of maintained erections reported previously. Sildenafil treatment was well tolerated. The most common adverse events were headache and flushing. In conclusion, sildenafil is a well-tolerated and effective treatment for ED of broad-spectrum etiology in Latin American men.     

Sildenafil citrate treatment for erectile dysfunction after kidney transplantation

OBJECTIVE: Our goal was to analyze the morbidity of organic erectile dysfunction (ED) in kidney-transplant patients and to evaluate the efficacy and reliability of sildenafil citrate treatment. METHOD: Sixty-five ED patients with normal graft function for 3 to 12 months after kidney transplantation were involved in our study. Erectile dysfunction was diagnosed in all the patients by the International Index of Erectile Dysfunction (IIEF). Among them, 10 patients were in light degree; 32 patients in moderate degree, and 23 patients in severe degree according to IIEF score. All of the patients underwent medical history, physical and chemical examinations. In each patient, the IIEF score, blood urea nitrogen, creatinine, and trough concentrations of cyclosporine were compared before and after taking sildenafil citrate at an initial dose of 50 mg every night. RESULTS: Twenty-six patients without ED before transplantation suffered ED after the operation, and 32 patients with ED before transplantation noticed worsening. Taking sildenafil citrate was effective in 53 patients (81.54%). There were no statistical differences in blood urea nitrogen, creatinine, or trough concentrations of cyclosporine in patients before and after sildenafil treatment. CONCLUSIONS: The morbidity of organic erectile dysfunction increased after transplantation. Sildenafil citrate treatment for ED in kidney-transplant patients was effective and safe. Graft function and trough concentrations of cyclosporine were not affected by sildenafil citrate.     

A baseline-controlled,open-label,flexible dose-escalation study to assess the safety and efficacy of sildenafil citrate (Viagra) in patients with erectile dysfunction

Although sildenafil citrate (Viagra) has demonstrated effectiveness in the treatment of erectile dysfunction (ED), the dosing regimens often used in clinical trials may not always match those employed in clinical practice. This study was undertaken to further assess the efficacy and safety of sildenafil taken as required in male outpatients 18 years of age and older with ED (n=71). It was conducted as a placebo-baseline-controlled, open-label, flexible dose-escalation study, with sildenafil (25,50, or 100 mg) administered for 8 weeks following a 4-week placebo run-in. Efficacy variables included questions 3 and 4 of the International Index of Erectile Function (IIEF), other IIEF domains, patient event logs, and quality-of-life (QOL) assessments. Treatment with sildenafil resulted in improvements from baseline in all IIEF domains analyzed (all P<0.0001), as well as overall QOL and amelioration of specific sexual and social relationships (all P&<0.0001). Sildenafil was well tolerated. One participant discontinued treatment because of adverse events. Results suggest that flexible dosing with oral sildenafil is safe and has beneficial effects on all indices of erectile function and QOL.     

西地那非治疗合并勃起功能障碍的早泄病人的临床观察

目的 :评价枸橼酸西地那非对合并勃起功能障碍 (ED)的早泄病人的临床疗效和安全性。　方法 :45例诊断为合并ED早泄病人 ,以西地那非片可调整用药方案治疗 1～ 3个月。以阴道内射精潜伏期及配偶性交满意度来评价早泄治疗效果 ,并评估ED的总体疗效和治疗满意度 ,比较治疗前后的国际勃起功能指数评分 5 (IIEF 5 )。　结果 :早泄改善者共 2 7例 ,有效率为 6 0 %。勃起功能改善者共 40例 ,改善率为 88.88%。 2 7例早泄有效者均为 5 0mg西地那非改善了勃起功能的病人 ,且满意率为81.48%;18例早泄无效者中ED治疗满意率仅为 5 .5 6 %。在早泄有效者和无效者间比较其治疗前、后IIEF 5评分及增加值 ,差异均有显著性 (P <0 .0 0 1)。不良反应共 9例(2 0 %) ,均为轻度或中度 ,未经特殊处理即自行缓解。　结论 :对合并ED的早泄病人 ,枸橼酸西地那非片能安全有效地改善其勃起功能 ,如获得满意疗效多能使病人早泄得到改善。     

The utility of sildenafil citrate for infertile men with sexual dysfunction: a pilot study

OBJECTIVE: To investigate the use the sildenafil citrate, recognized as a first-line therapy for men with erectile dysfunction (ED), and which is safe and effective in men with various causes and severity of ED, including psychogenic ED, in a population of infertile men with sexual dysfunction. PATIENTS AND METHODS: Infertility is a major source of life stress and might be associated with sexual dysfunction through the erosion of self-esteem and self-confidence, and in stimulating discord in a relationship. Men presenting for evaluation of fertility who on questioning by the physician reported the recent onset of sexual dysfunction, had a history taken, a physical examination, hormonal profile, and completed the International Index of Erectile Function (IIEF), a validated inventory for assessing sexual dysfunction. Thirty men with a score of <26 on the erectile function domain of the IIEF, or who complained of new onset rapid or delayed ejaculation, were treated with sildenafil with no randomization or placebo control. The evaluation was repeated and the IIEF completed again > or =3 months after starting treatment. RESULTS: For men complaining of ED, subjective erectile rigidity, duration of erection, and the percentage of successful penetration attempts significantly improved with sildenafil. The mean (sd) IIEF domain scores for erection and satisfaction, at 18 (4) vs 27 (3), and 12 (2) vs 16 (3) (both P = 0.01), and orgasm, at 4 (1) vs 6 (3) (P = 0.001), respectively, significantly improved after treatment. In patients with ejaculatory dysfunction, the function improved in 64% after sildenafil therapy. CONCLUSIONS: We identified the nature of sexual dysfunction associated with male-factor infertility, and showed the efficacy of sildenafil therapy in men with this condition.     

Is sildenafil citrate an alternative agent in the evaluation of penile vascular system with color Doppler ultrasound?

IINTRODUCION: The ideal diagnosis and therapeutic agent for erectile dysfunction (ED) would be an oral drug taken prior to color Doppler ultrasound (CDU) examination and sexual intercourse. In the present study we have investigated if the efficacy of oral sildenafil is optimal in the diagnosis of underlying pathology of ED. MATERIAL AND METHODS: The study group comprised of 41 patients with ED. Firstly, all patients underwent CDU examinations after the combined intracavernosal injection of 60 mg of papaverine and sexual stimulation (CIS). Secondly, these patients were examined after taking 50 mg of oral sildenafil citrate combined with self-manual and visual sexual stimulation. RERSULTS The differences of peak systolic velocity values were statistically significant between CIS and sildenafil (right: 40.7 +/- 2.9 vs. 28.7 +/- 3.3; left: 41.2 +/- 3.3 vs. 25.7 +/- 2.4; p < 0.001) in patients with normal penile vascular system. However, end-diastolic velocity and resistance index values were not significant between the same groups. In addition, there were not significant differences for peak systolic and end-diastolic blood flow velocities and resistances index with CIS and sildenafil in cases with vasculogenic ED. CONCLUSIONS: Sildenafil citrate plus visual sexual stimulation is not reliable as CIS to make accurate interpretation of penile vascular status using CDU. On the other hand, in some cases suspected of psychogenic ED after detailed sexual history, sildenafil might be tried as an initial step of the functional evaluation with CDU in order to prevent prolonged erection risk with intracavernosal injection of vasoactive agents.