Oral pharmacotherapy for erectile dysfunction: current perspectives

Evaluation of the effects of sildenafil citrate (viagra) on vertebral artery blood flow in patients with vertebro-basilar insufficiency

Objective

To investigate the effects of sildenafil citrate (Viagra) on the vertebral artery blood flow of patients with vertebro-basilar insufficiency (VBI) using color duplex sonography (CDS).

Materials and Methods

The study included 21 patients with VBI (aged 31-76; mean 61.0 ± 10.5 yrs). We administered a 50 mg oral dose of sildenafil citrate to all patients. Next, we measured the peak systolic velocity (Vmax), end diastolic velocity (Vmin), resistive index (RI), pulsatility index (PI), diameter, area, and flow volume (FV) of vertebral arteries using CDS before the administration of sildenafil citrate; 45 minutes after, and 75 minutes after administration. Statistical testing was performed using SPSS for windows version 11.0. The statistical test used to determine the outcome of the analysis was the repeated measures analysis of variance (ANOVA) test.

Results

Compared to the baseline values, the vertebral artery diameter, area, and FV increased significantly following the administration of sildenafil citrate. The diameter, area and FV increased from 3.39 mm at 45 minutes to 3.64 mm at 75 minutes, 9.43 cm² to 10.80 cm² at 45 minutes and 10.81 cm² at 75 minutes, as well as from 0.07 L/min at baseline to 0.09 L/min at 45 minutes and unchanged at 75 minutes, respectively.

Conclusion

Sildenafil citrate elicited a significant effect on vertebral artery diameter, area and FVs.

Effects of Sildenafil Citrate (Viagra®) on Renal Arteries: An Evaluation with Doppler Ultrasound

INTRODUCTION

We aimed to determine hemodynamic alterations in renal arteries that may have resulted from oral intake of sildenafil citrate in healthy volunteers.

MATERIALS AND METHODS

Twelve healthy volunteers were included in our study. Renal Doppler ultrasonography (US) was performed before the drug intake to assess the basal values. Maximum peak systolic velocity, and resistivity and pulsatility indices were measured from the segmental branches of both renal arteries in all the examinations. After the basal measurements 50 mg of sildenafil or placebo were randomly given to the 12 subjects. Renal Doppler US examinations were carried out 1 h after sildenafil or placebo intake. On the following day sildenafil was administered to the subjects who had previously taken placebo or vice versa. Renal Doppler US was repeated after 1 h. The effect of sildenafil on renal vascular hemodynamics was evaluated by comparison of basal values with postplacebo and postsildenafil values.

RESULTS

No statistically significant differences were found between the basal values of bilateral renal arteries and maximum peak systolic velocity, and resistivity and pulsatility index values measured after the placebo or sildenafil intake.

CONCLUSION

We demonstrated that single-dose sildenafil did not cause any significant effect on renal artery hemodynamics in healthy individuals.

Hemodynamic effects of sildenafil citrate (Viagra) on segmental branches of bilateral renal arteries

INTRODUCTION

Erectile dysfunction (ED) is one of the most encountered male health problem and sildenafil citrate is used worldwide for treatment of ED. Aim of the present study was to determine and evaluate hemodynamic effects of sildenafil citrate on segmental branches of bilateral renal arteries of cases with ED.

PATIENTS AND METHODS

Total of 35 male patients aging between 34 and 56 years were recruited into study. Patients were evaluated with renal color Doppler sonography (CDS) before and after (45-75 min) peroral sildenafil citrate (50 mg) administration. Peak systolic flow rate (V(max)), end diastolic flow rate (V(min)), resistive index (RI) and pulsatility index (PI) of renal artery segmental branches were determined before and after sildenafil citrate administration.

RESULTS

V(min) measured at right lower segment was significantly reduced after sildenafil administration (p = 0.030). Accordingly mean RI and PI of right lower segment of renal artery slightly increased after drug administration (p = 0.007 and p = 0.012, respectively). The measurements on other segments had no significant change after sildenafil treatment when compared to baseline values. On this single dose administration no side effect was recorded.

CONCLUSION

Findings of the present study demonstrated that peroral sildenafil citrate usage had slight effects on hemodynamic parameters of lower segmental branch of right renal artery. This result could not be interpreted as robust evidence for hemodynamic changes of renal arteries associated with sildenafil usage nevertheless warrants more comprehensive research with larger number of patients.

Effects of sildenafil on major arterial blood flow using duplex sonography

PURPOSE

Erectile dysfunction (ED) is the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual performance. Oral use of sildenafil citrate is effective in the treatment of ED. Although the effects of sildenafil citrate have been investigated in several systems, its effect on aortic, superior mesenteric (SMA), and carotid artery blood flow is still unclear. The aim of this study is to investigate the early phase effects of sildenafil citrate on aortic, SMA, and carotid artery blood flow using color duplex sonography (CDS).

METHODS

Thirty-four patients with ED (aged 19-71) were included in this study. Peak systolic velocity, end diastolic velocity, and resistance index (RI) in aorta, SMA, and bilateral common and internal carotid arteries were measured at baseline and 45-75 minutes after the administration of sildenafil citrate using CDS.

RESULTS

Statistically significant changes were observed in only 3 of 18 parameters: an increase in post drug values of bilateral internal carotid artery peak systolic velocity (Vmax) compared to baseline values and a significant decrease in the RI value of the left main carotid artery after drug administration compared to baseline values.

CONCLUSIONS

Sildenafil citrate had no significant effect on aortic and SMA circulation and only caused mild changes in the carotid artery circulation. Although these alterations may be considered clinically insignificant, further studies assessing long-term effects of sildenafil are warranted.

Sustained efficacy and tolerability of vardenafil, a highly potent selective phosphodiesterase type 5 inhibitor, in men with erectile dysfunction: results of a randomized, double-blind, 26-week placebo-controlled pivotal trial

The durability of key efficacy response parameters and safety of vardenafil was evaluated in a pivotal trial conducted in a broad population of men with erectile dysfunction (ED) in North America. In this randomized, double-blind, placebo-controlled, multicenter, fixed-dose, parallel-group, 6-month comparison study, men >18 years of age with ED for >6 months received 5-mg, 10-mg, and 20-mg doses of vardenafil as needed for up to 26 weeks. The primary efficacy variables were the International Index of Erectile Function (IIEF)-Erectile Function (EF) domain scores, and the Sexual Encounter Profile (SEP) mean per-patient success rates for penetration (SEP question 2) and maintenance of erections (SEP question 3). Safety data were also collected over time. Improvement in all primary efficacy variables was observed in all vardenafil groups versus placebo. These improvements occurred early and were either sustained or increased through week 26. Vardenafil in 10-mg and 20-mg doses was significantly superior to placebo at all time points for all efficacy variables (P <0.01), and all doses were superior to placebo at endpoint (P <0.001). Most treatment-emergent adverse events (headache, flushing, dyspepsia, and rhinitis) were mild or moderate in intensity, and incidence generally decreased over time. All 3 doses of vardenafil were superior to placebo across all primary efficacy variables and all study time points in a broad range of patients with ED, regardless of etiology or severity. Vardenafil was well tolerated. These results demonstrate that vardenafil provides sustained efficacy with reduced incidence of nuisance side effects over time. High resolution video, medium resolution video, low resolution video.

Incidence and determinants of sildenafil (dis)continuation: the Dutch cohort of sildenafil users

Sildenafil utilization was prospectively evaluated among 153 men with a history of erectile dysfunction (ED)-prescription drug use prior to starting sildenafil and 164 men who were new starters of ED-prescription drugs. Further, some determinants of sildenafil discontinuation were identified. During a median follow-up period of 18 months 45% of all patients discontinued sildenafil treatment, regardless of earlier treatment history. However, patients with a history of drug treatment for ED were nearly eight times as likely to switch or re-start another ED-prescription drug after discontinuing sildenafil compared to previously untreated users. Age >60 y, diabetes medication, nitrate use, and use of incontinence pads (a proxy for disease/surgery in the pelvic region) were associated with an increased likelihood of discontinuing sildenafil. Although the introduction of sildenafil reduced the barrier to seek medical help for erectile problems, sildenafil treatment failure in previously untreated patients results in a high dropout rate from further ED drug treatment of any kind.

The correlation between penile tumescence measured by the erectometer and penile rigidity by the RigiScan

BACKGROUND

The goal of this study was to evaluate the correlation between increments of penile tumescence and penile rigidity measured by the erectometer and the RigiScan, respectively.

METHODS

Nocturnal penile tumescence (NPT) was measured in 25 volunteers (mean age, 49.5 years). The erectometer and the RigiScan were used simultaneously for a total of 47 nights. We studied the correlation between maximum penile circumferential changes determined by the erectometer and penile rigidity patterns measured by the RigiScan.

RESULTS

Maximum circumferential changes during NPT measured by the erectometer were well correlated to those determined by the RigiScan (correlation coefficient, 0.719). In addition, penile circumferential changes measured by the erectometer corresponded well to the penile rigidity pattern determined by the RigiScan (P=0.0001). Specifically, maximum penile circumferential changes of more than 30 mm and less than 10 mm had 70% positive predictive value and 100% negative predictive value for predicting the normal rigidity pattern, respectively.

CONCLUSIONS

Penile circumferential changes measured by the erectometer were well correlated to penile rigidity measured by the RigiScan, particularly when the increments were larger than 30 mm or less than 10 mm. These results suggested that the erectometer was a useful tool to estimate the penile rigidity patterns of the RigiScan.

An open-label, uncontrolled dose-optimization study of sublingual apomorphine in erectile dysfunction

BACKGROUND

Because apomorphine is a dopamine agonist that acts on areas of the central nervous system believed to mediate penile erection, its use in erectile dysfunction (ED) has been investigated. However, it also produces nausea by dopamine-receptor stimulation of the chemotrigger zone in the brain. Therefore, a low plasma concentration, achieved rapidly, would be selective for the desired erectile response but would be below the dopamine threshold for nausea.

OBJECTIVE

We evaluated the efficacy and tolerability of a dose-optimized regimen of a sublingual formulation of apomorphine (apomorphine SL) in the treatment of ED.

METHODS

This was a multicenter, open-label, uncontrolled, Phase III dose-optimization study of apomorphine SL in heterosexual men with ED. The 2-week screening period, during which baseline severity of ED was determined using the International Index of Erectile Function, was followed by a 3-week dose-optimization period beginning at a dose of 2 mg. Patients were to make at least 2 attempts at intercourse per week throughout the study, placing 1 apomorphine tablet under the tongue beforehand. At the end of the first week, the dose could be increased to 3 mg at the discretion of the investigator; at the end of the second week, the dose could be increased to a maximum of 4 mg or decreased as needed. In the following 4-week treatment period, patients took their individual optimal doses. The primary efficacy variable was the percentage of attempts resulting in erections firm enough for intercourse, as assessed by investigators' review of data from patients' diaries. Secondary variables included the percentage of attempts resulting in successful intercourse, time to erection, and duration of erection. Information about adverse events, including their severity and relation to treatment, was determined on the basis of direct questioning, spontaneous reports, and review of patient diaries.

RESULTS

The study enrolled 849 heterosexual men whose ages ranged from 31 to 78 years (mean, 58.1 years). They had a mean 5.7-year history of ED of varbus causes. ED was mild in 11.5% of the men, moderate in 23.8 c, and severe in 48.1%. When results of the last 8 attempts were pooled, representing the period during which patients were taking their optimal doses of apomorphine SL, the mean percentage of attempts resulting in erections firm enough for intercourse was 39.4%, compared with 13.1% at baseline; attempts resulting in intercourse increased from a mean of 12.7% at baseline to 38.3% with treatment. The average median time to erection was 23 minutes, and the average median duration of erection was 13 minutes. Nausea, the most common treatment-related adverse event (11.7%). was dose related and diminished with continued dosing. One patient had a single syncopal episode that was judged to be related to apomorphine SL.

CONCLUSIONS

In the present study, a dose-optimization regimen of apomorphine SL-with dosing initiated at 2 mg and adjusted up to a maximum of 4 mg as needed-was effective and well tolerated in the treatment of ED, regardless of its cause or severity.

Sildenafil citrate for penile hemodynamic determination: an alternative to intracavernosal agents in Doppler ultrasound evaluation of erectile dysfunction

OBJECTIVES

To suggest a new noninvasive method for penile Doppler ultrasound (PDU) evaluation of erectile dysfunction using oral sildenafil citrate as an erection induction agent.

METHODS

A total of 20 patients admitted with the complaint of erectile dysfunction were evaluated by the short form of the International Index of Erectile Function. A total score of less than 25 was accepted as erectile dysfunction and PDU was performed. The initial penile study consisted of PDU examination under visual sexual stimulation (VSS), and the peak systolic velocity, end-diastolic velocity, and resistance index were recorded. Measurements of all the parameters were repeated on the same patients after intracavernosal papaverine, intracavernosal prostaglandin E(1) (PGE(1)), and oral sildenafil citrate administration, plus VSS. All patients had these four tests in the same order at weekly intervals. Sildenafil citrate was given orally 45 minutes before Doppler investigation, and patients had VSS during the waiting period. The patients were asked about their satisfaction and comfort after each test. Statistical analysis was performed using the Wilcoxon and Mann-Whitney U tests.

RESULTS

The measurements with papaverine, PGE(1), and sildenafil citrate were significantly different from those after only VSS (P <0.008); however, the papaverine, PGE(1), and sildenafil citrate results were not different from each other according to the peak systolic velocity, end-diastolic velocity, and resistance index measurements (P >0.008). Patients commented that although PGE(1) was the strongest erectogenic agent, sildenafil citrate was the most convenient.

CONCLUSIONS

Since the results of PDU with oral sildenafil citrate in association with VSS were not statistically different, we suggest a new noninvasive erection induction method for the purpose of PDU evaluation of erectile dysfunction.