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PubMed2005

Inactivation of phosphorylated endothelial nitric oxide synthase (Ser-1177) by O-GlcNAc in diabetes-associated erectile dysfunction.

Impaired endothelial nitric oxide synthase (eNOS) function is associated with erectile dysfunction in diabetes mellitus, but the exact molecular basis for the eNOS defect in the diabetic penis remains unclear. We investigated whether hyperglycemia increases O-GlcNAc modification of eNOS in the penis, preventing phosphorylation at the primary positive regulatory site on the enzyme and hampering mechanisms of the erectile response. Type I diabetes mellitus was induced in male rats by alloxan (140 mg/kg, i.p.). After 5 wk, the diabetic rat penis exhibited increased O-GlcNAc modification of eNOS and decreased eNOS phosphorylation at Ser-1177 at baseline compared with the control rat penis; eNOS phosphorylation at Thr-495, Ser-615, and Ser-633 was not affected. In addition, eNOS phosphorylation at Ser-1177 was impaired in the diabetic rat penis in response to penile blood flow (shear stress) elicited by electrical stimulation of the cavernous nerve (ES) and to recombinant human VEGF165. Phosphorylation of Akt, a mediator of shear stress-induced eNOS phosphorylation at Ser-1177, was decreased in the diabetic penis at baseline, but it was restored by ES. Erectile response to shear stress elicited by ES and to VEGF was decreased in diabetic compared with control rats. This work demonstrates that eNOS inactivation occurs in the diabetic penis by a glycosylation mechanism specifically at Ser-1177, by which the enzyme is rendered incapable of activation by fluid shear stress stimuli and VEGF signaling. In vivo penile erection paradigm supports the physiologic relevance of O-GlcNAc modification in vascular disorders associated with diabetes.

Acetylglucosamine↗

PubMed2000

Yohimbine in erectile dysfunction: the facts.

Yohimbine, a pharmacologically well-characterized alpha-2-adrenoceptor antagonist with activity in the central and peripheral nervous system, has been used for over a century in the treatment of erectile dysfunction. In-depth, systematic studies in animals have shown that the drug has a remarkable positive effect on sexual performance. Meta-analyses of the few controlled, randomized human studies have consistently shown an advantage of yohimbine over placebo. Despite such a long history and encouraging activity, the drug has not yet been subjected to scientifically rigorous human clinical trials. Although relevant basic pharmacological and animal research information has been available for over 15 y, recent studies were designed with a lack of insight and complete disregard of those fundamental studies. Currently, dose-response investigations are not available, alternative routes of administration (i.e. sublingual) have not been investigated, nor has continuous versus 'on-demand' administration been explored. Synergistic activity with other drugs was last studied nearly four decades ago. Assessment of various populations was carried out in very limited cohorts and only in most general terms. In short, properly designed trials in humans have not been done. Why? Yohimbine is an old drug. As such it does not enjoy patent protection or commercial viability. Until molecular/formulation changes can be brought about (as recently happened with two other agents: phentolamine and apomorphine), serious investigations of yohimbine will remain in limbo. It could be that the nay sayers are right and yohimbine, indeed, lacks clinical activity as a treatment for men with erectile dysfunction. As long as it remains an orphan drug, we will never know.

Adrenergic alpha-Antagonists↗

PubMed2004

Erectile dysfunction associated with scleroderma: a case-control study of men with scleroderma and rheumatoid arthritis.

OBJECTIVE: To determine if men with systemic sclerosis (SSc) are at increased risk of developing erectile dysfunction (ED) compared to men with rheumatoid arthritis (RA), and to investigate the temporal relationship of ED related to rheumatologic disease. METHODS: Men with SSc identified from the practices of 2 rheumatologists were age matched to men with RA and were sent a standardized, validated questionnaire (SHIM IIEF-5) to assess ED and related factors. The questionnaire also addressed information on the subject's overall health and rheumatic disease status. RESULTS: The response rate was 50% (48% in SSc and 55% in RA), thus 43 with SSc and 23 with RA were included. The mean age of respondents was 53 yrs +/- 1.34 (SEM), (range 34 to 83). No statistical differences were found for marital status, alcohol or drug use, or past/present smoking. Men with scleroderma weighed less than men with RA (p < 0.004) and were more likely to have Raynaud's phenomenon (p < 0.0001), and to have fewer biological children (2.0 +/- 0.2 vs 2.7 +/- 0.2, p < 0.01). The prevalence of erectile dysfunction was 81% (SSc) and 48% (RA), (relative risk for SSc vs RA: 4.77; 95% CI: 1.55, 14.66; p < 0.005). In subjects who had ED, 78% (both SSc and RA) reported it occurring after disease onset. Men with SSc noted their ED began 2.7 +/- 1.2 (mean +/- SEM) years after their disease was diagnosed, and similarly, men with RA noted their ED began 3.3 +/- 2.2 years after disease diagnosis, p = 0.82. Eighty-six percent of patients with SSc had Raynaud's phenomenon (RP) compared to 19% RA, p < 0.0001. Eighty percent of subjects with RP (SSc + RA) had ED versus 50% of men without RP, p < 0.01. In RA subjects with RP (n = 4), 75% had experienced ED, versus 39% of RA without RP, p = 0.18. Possible confounding factors for ED were examined including smoking, hypertension, diabetes, and steroid use; all except self-reported history of nerve damage (p < 0.0005) and diabetes (p < 0.02) were insignificant for predicting the likelihood of increased ED. Patients with SSc were not more likely than RA to have experienced nerve damage (p = 0.25), or diabetes (p = 0.19). CONCLUSION: ED occurs frequently in SSc, is more common than in RA, and occurs on average 3 years after disease onset. RP appears to be associated with ED in both SSc and RA, but is not necessarily an independent risk factor for ED in SSc alone.

Adult↗

PubMed2004

Relationship between metabolic syndrome and erectile dysfunction.

AIM: To determine the relationship between metabolic syndrome (MS) and erectile dysfunction (ED) and to see which risk factors correlated the best with ED. METHODS: Seventy-nine cardiology clinic outpatients with coronary artery disease (CAD) and lipid metabolism disorder were recruited. They were categorized as having MS, hypertension (blood pressure greater than 130/85 mmHg) and dyslipidemia. ED was classified based on International Index of Erectile Function scores. Patients were grouped into quartiles based on body mass index (BMI). Chi-square, Pearson's correlation and regression tests were used for statistical analysis. RESULTS: The mean age of the patients was 56.6 years. ED was diagnosed in 59 (74.7 %) of the 79 patients. In the 38 patients with MS, all had ED. ED was not significantly correlated with cholesterol levels (P>0.05), but was found often in patients who had both hypercholesterolemia and HT (P<0.01). Nineteen (76 %) of the 25 patients who had dyslipidemia had ED. However, ED was not significantly correlated with dyslipidemia (P >0.05). Twenty-two of the 23 patients who had BMI greater than 30 had ED, which was significantly more prevalent than that in those who had normal BMI (P<0.01). ED was seen in 38 of 53 smoker patients. Although ED was more prevalent in cigarette smokers, it was not significantly different from non-smokers (P>0.5). CONCLUSION: ED is present in a high percentage of patients with MS. Among multiple risk factors for ED, MS correlates the most highly. The next most important risk group is the patients with hypertension +hypercholestrolemia and obesity (BMI 30).

Adult↗

PubMed1999

Lack of sexual activity from erectile dysfunction is associated with a reversible reduction in serum testosterone.

The role of androgenic hormones in human sexuality, in the mechanism of erection and in the pathogenesis of impotence is under debate. While the use of testosterone is common in the clinical therapy of male erectile dysfunction, hypogonadism is a rare cause of impotence. We evaluated serum testosterone levels in men with erectile dysfunction resulting either from organic or non-organic causes before and after non-hormonal impotence therapy. Eighty-three consecutive cases of impotence (70% organic, 30% non-organic, vascular aetiology being the most frequent) were subjected to hormonal screening before and after various psychological, medical (prostaglandin E1, yohimbine) or mechanical therapies (vascular surgery, penile prostheses, vacuum devices). Thirty age-matched healthy men served as a control group. Compared to controls, patients with impotence resulting from both organic and non-organic causes showed reduced serum levels of both total testosterone (11.1 +/- 2.4 vs. 17.7 +/- 5.5 nmol/L) and free testosterone (56.2 +/- 22.9 vs. 79.4 +/- 27.0 pmol/L) (both p < 0.001). Irrespective of the different aetiologies and of the various impotence therapies, a dramatic increase in serum total and free testosterone levels (15.6 +/- 4.2 nmol/L and 73.8 +/- 22.5 pmol/L, respectively) was observed in patients who achieved normal sexual activity 3 months after commencing therapy (p < 0.001). On the contrary, serum testosterone levels did not change in patients in whom therapies were ineffective. Since the pre-therapy low testosterone levels were independent of the aetiology of impotence, we hypothesize that this hormonal pattern is related to the loss of sexual activity, as demonstrated by its normalization with the resumption of coital activity after different therapies. The corollary is that sexual activity may feed itself throughout the increase in testosterone levels.

Adolescent↗

PubMed2005

Testosterone therapy in erectile dysfunction and hypogonadism.

INTRODUCTION: Laboratory experiments indicate that the nitric oxide erectile pathway is testosterone-dependent. Castration induces erectile dysfunction (ED) and reduction in nitric oxide synthase and in phosphodiesterase type 5 (PDE5) in the erectile tissue. Furthermore, castration causes apoptosis adversely affecting smooth muscle content and penile hemodynamics leading to veno-occlusive dysfunction. Testosterone therapy reverses these structural, biochemical, and physiological changes. In humans, testosterone therapy improves erectile function in men with hypogonadism. However, the efficacy of testosterone monotherapy may not be adequate because of the multifactorial nature of the pathophysiology of ED. METHODS: Preliminary data from a number of studies have been reviewed. RESULTS: There are emerging evidence-based benefits to using the combination of testoterone and PDE5 inhibitors. A recently published multicenter, randomized, placebo-controlled study evaluated the safety and efficacy of testosterone gel 1% plus sildenafil vs. placebo gel plus sildenafil, in producing an erectile response in hypogonadal men who had failed prior sildenafil alone for ED. Screening yielded a prevalence of hypogonadism in ED patients who failed prior sildenafil. Following randomization, the double-blinded treatment phase was 12 weeks. Testosterone therapy with testosterone gel significantly improved erectile function in response to sildenafil. In addition, it significantly improved orgasmic function and patient satisfaction. CONCLUSION: It is important to screen all men with ED for hypogonadism, especially those with a history of inadequate response to prior PDE5 inhibitors. The combination of testosterone plus PDE5 inhibitors may be considered for the treatment of ED in men with low to low-normal testosterone levels, who had inadequate response to prior treatment with PDE5 inhibitors alone.

Androgens↗

PubMed2006

Efficacy and safety of sildenafil in men with serotonergic antidepressant-associated erectile dysfunction: results from a randomized, double-blind, placebo-controlled trial.

OBJECTIVE: To evaluate the efficacy of short-term treatment with sildenafil citrate in men with serotonin reuptake inhibitor (SRI)-associated erectile dysfunction (ED). METHOD: Men (aged>or=18 years) with major depressive disorder (MDD; DSM-IV criteria) in remission and taking SRIs who experienced SRI-associated ED were enrolled in this multicenter, 6-week, randomized, flexible-dose, double-blind, placebo-controlled trial. The primary study measures were questions 3 (Q3: frequency of penetration) and 4 (Q4: frequency of maintained erections after penetration) of the International Index of Erectile Function (IIEF) questionnaire. Secondary study measures were all other questions and domains of the IIEF, the Erectile Dysfunction Index of Treatment Satisfaction (EDITS), a global efficacy questionnaire (GEQ), and a patient-maintained event log of sexual activity. RESULTS: Patients receiving sildenafil (N=71) versus placebo (N=71) reported significantly higher mean+/-SE scores on Q3 (3.9+/-0.2 vs. 3.1+/-0.2, p=.003) and Q4 (3.7+/-0.2 vs. 2.8+/-0.2, p<.001) of the IIEF and significantly higher scores on all domains of the IIEF. Patients receiving sildenafil also reported significantly improved scores on all questions of the EDITS questionnaire (p<.02) and the GEQ (p<.0001) and an increased number of successful sexual intercourse attempts per week (p<.0001) compared with patients receiving placebo. All patients remained in MDD remission (score<or=10 on the Hamilton Rating Scale for Depression). Adverse events in patients taking sildenafil (vs. placebo) were headache (9% vs. 9%), dyspepsia (9% vs. 1%), anxiety (6% vs. 4%), and abnormal vision (3% vs. 0%). CONCLUSIONS: Short-term (6-week) administration of sildenafil was well tolerated and significantly improved erectile function and overall sexual satisfaction in men with ED associated with SRI therapy for MDD. Sildenafil may be successfully used to treat SRI-associated ED without interruption of antidepressant therapy.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed1997

Alterations in endothelin B receptor sites in cavernosal tissue of diabetic rabbits: potential relevance to the pathogenesis of erectile dysfunction.

PURPOSE: Diabetes Mellitus (DM) is a major risk factor for erectile dysfunction in both patients and animal models. The pathogenesis of this dysfunction has not been fully elucidated. However, alterations in the synthesis of a number of vasoactive compounds, such as nitric oxide (NO) and prostacyclin (PGI2), have been reported in various diabetic tissues. The interaction between NO, PGI2 and endothelin-1 (ET-1), a powerful vasoconstrictor and smooth muscle cell mitogen, is thought to be important in maintaining vascular tone and the erectile process. We investigated the density and distribution of ET-1 and endothelin receptor subtypes in cavernosal tissue and assessed any changes brought about by DM in a rabbit model. MATERIALS AND METHODS: DM was induced in New Zealand White rabbits using alloxan. Penises were excised from the diabetic rabbits three months (n = 6) and six months (n = 6) after the induction of DM. Low and high resolution autoradiography was performed using radioligands for ET-1, endothelin A (ETA) and endothelin B (ETB) receptors and were analyzed densitometrically. The results were compared with those from six age-matched healthy control rabbits for each group. Immunohistochemical localization of ET-1 immunoreactivity was also performed, together with ultrastructural evaluation of the corpus cavernosum. RESULTS: ET-1, ETA and ETB receptor binding sites were primarily localized to the smooth muscle cells of the corpus cavernosum and the endothelium lining the cavernosal spaces. A significant increase in ETB receptor binding sites was found only in cavernosal tissue six months after induction of DM, when compared with age-matched healthy controls. These receptor changes were accompanied by ultrastructural changes in the corpus cavernosum indicative of an early, atherosclerosis-like process. CONCLUSIONS: The autoradiographic and immunohistochemical findings in this study suggest that ET-1 may have a role in the pathophysiology of diabetic ED. This peptide may be released in an autocrine fashion causing cavernosal smooth muscle cell (CSMC) contraction and/or proliferation.

Animals↗

PubMed2006

JNJ-10280205 and JNJ-10287069: Novel PDE5 inhibitors as clinical candidates for erectile dysfunction.

Phosphodiesterase 5 (PDE5) inhibitors are efficacious in treating patients with erectile dysfunction. New PDE5 inhibitors with different selectivity and pharmacokinetic profiles have been vigorously pursued. Here we report two novel, potent, and selective PDE5 inhibitors, JNJ-10280205 and JNJ-10287069, with Ki values of 0.05 and 0.12 nM, respectively. Both compounds displayed superior selectivity against PDE1-4 and -6 when compared to sildenafil. In the anesthetized dogs, JNJ-10280205 and JNJ-10287069 exhibited similar efficacy as sildenafil in enhancing erectile functions, with no significant effect on cardiovascular parameters. Pharmacokinetic studies showed that JNJ-10287069 had better oral bioavailability than JNJ-10280205 in several animal species. In vitro study suggested that cytochrome P450 (CYP) 3A4 played a major role in the metabolism of both compounds. The compounds inhibited some of the CYP450 enzymes and the human ether-a-go-go (HERG) channel at much higher concentrations than that required to inhibit PDE5, thus, no cross inhibition would be expected at therapeutic doses. Both compounds are suitable clinical candidates.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed1995

Nitric oxide donor, linsidomine chlorhydrate (SIN-1), in the diagnosis and treatment of erectile dysfunction: critical appraisal and review of the literature.

Recent experimental work has demonstrated that nitric oxide (NO) is the neutrotransmitter responsible for cavernous smooth muscle relaxation. Different studies on the performance of the direct NO-donor linsidomine chlorhydrate (SIN-1) in patients with erectile dysfunction have come to conflicting results ranging from highest praise to complete dismissal. We reviewed all published studies on the use of SIN-1 for intracorporeal injection in erectile failure including our own. To this date, 3 groups published their data. Only the uncontrolled data from Hannover claim good results. The controlled data from Hamburg and Berlin on patients with erectile failure due to venous leakage, to a mixed aetiology in a double-blind fashion and to mixed aetiology with drug increase (1 mg versus 2 mg of SIN-1) showed a significantly worse performance of SIN-1 compared to the standard drug for penile injection, prostaglandin E1. We conclude that there is no place for linsidomine chlorhydrate in either the diagnosis or the treatment of erectile dysfunction.

Animals↗

PubMed2005

A double blind, randomised study of sildenafil citrate for erectile dysfunction in men with multiple sclerosis.

OBJECTIVE: Identifying and effectively treating erectile dysfunction (ED) can result in an improvement of the quality of life (QoL) in men with multiple sclerosis (MS). METHODS: This randomised, double blind (DB), placebo controlled, flexible dose study with an open label extension (OLE) assessed efficacy, QoL, and safety of sildenafil citrate in men with MS and ED. Overall, 217 men received sildenafil (25-100 mg; n = 104) or placebo (n = 113) for 12 weeks. Efficacy was assessed by the International Index of Erectile Function (IIEF) questionnaire that includes questions on achieving (Q3) and maintaining (Q4) an erection as well as a global efficacy question (GEQ). QoL was also assessed. RESULTS: After 12 weeks, patients receiving sildenafil had higher mean scores for IIEF Q3 and Q4 compared with those receiving placebo (p<0.0001), and 89% (92/103) reported improved erections compared with 24% (27/112) of patients receiving placebo (p<0.0001). At the end of the OLE phase, 95% of men reported improved erections. Patients receiving placebo during the DB phase showed a nearly fourfold increase in improved erections (97% v 26%). Men receiving sildenafil also showed improvements in five of the eight general QoL questions compared with men receiving placebo (p<0.05). The total mean score for the QoL questionnaire improved by 43% for the sildenafil group versus 13% for the placebo group (p<0.0001). Treatment related AEs were predominantly mild in nature, and no patient discontinued due to an AE. CONCLUSION: Sildenafil treatment for ED in men with MS was effective and well tolerated, and resulted in significant improvements in both general and disease specific QoL variables.

Adult↗

PubMed2006

The treatment of erectile dysfunction study: focus on treatment satisfaction of patients and partners.

OBJECTIVE: To assess patient and partner preferences for, and satisfaction with, tadalafil or sildenafil (phosphodiesterase type 5 inhibitors) in routine clinical practice for treating erectile dysfunction (ED), as these are important outcomes that might influence treatment adherence. PATIENTS AND METHODS: In a multicentre, prospective observational trial in Canada, patients with ED were eligible if they planned to change treatment from tadalafil to sildenafil or vice versa. Data were collected at baseline and 4-12 weeks later (endpoint). Satisfaction was assessed using patient and partner versions of the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) questionnaire. EDITS index scores range from 0 (extremely low treatment satisfaction) to 100 (extremely high treatment satisfaction). RESULTS: Of 2425 patients, approximately 98% completed the study and 295 partners participated. When patients changed from sildenafil to tadalafil (1722 men) the mean EDITS index scores increased significantly for both patients (from 61.6 to 78.3) and partners (from 65.0 to 82.6; both P < 0.001). When patients changed from tadalafil to sildenafil (703 men), the mean EDITS index scores increased slightly but significantly for patients (from 68.8 to 70.2; P = 0.007) but not partners (from 76.8 to 68.9; P = 0.066). For the individual EDITS questions, mean scores increased significantly from baseline to endpoint on all questions for patients (all 11 questions; P < 0.001) and partners (all five questions; P < 0.001) in the sildenafil-to-tadalafil group, and in the tadalafil-to-sildenafil group, mean scores for patients decreased on nine of 11 questions (seven of nine significantly; P < 0.041) and mean scores for partners decreased on all five (two significantly; P < 0.049). For treatment preference, regardless of the change in treatment (i.e. sildenafil-tadalafil or tadalafil-sildenafil), a significantly higher percentage of patients and partners preferred tadalafil to sildenafil. CONCLUSIONS: These data indicate that patients with ED (and their partners) who changed from sildenafil to tadalafil treatment or vice versa in a routine clinical practice setting had higher treatment satisfaction when taking tadalafil than sildenafil, as assessed by most measures of EDITS. The higher treatment satisfaction with tadalafil might help to explain the greater preference for tadalafil compared with sildenafil in both patients and partners in this observational study.

Carbolines↗

PubMed1982

Hormonal variations during sleep in men with erectile dysfunction and normal controls.

Five physically healthy young males suffering from erectile impotence and five normal controls of similar age are the subjects of this preliminary report. All were studied in the sleep laboratory during 3 to 5 nights with the last two devoted to sequential hormonal sampling by means of an indwelling venous catheter. Electroencephalogram, eye movements, and penile tumescence were monitored continually through the night. Plasma LH, FSH, and testosterone were measured every 20 minutes by radioimmunoassay. There were no differences between the patients with erectile impotence and normal controls in all sleep parameters investigated, including mean tumescent time, time in simultaneous REM and tumescence, and number of full and partial tumescent episodes. Marked fluctuations in plasma LH, FSH, and testosterone were observed during sleep without differences noted between the two groups. Mean plasma LH, but not FSH or testosterone, was significantly lower in the impotent men. There were no significant differences in mean plasma gonadotrophins and testosterone between tumescent episodes and nontumescent periods in either group. A significant relation was found in normals, but not in the men with erectile dysfunction, between the occurrence of REM sleep and abrupt elevations in testosterone. Testosterone levels during REM sleep with tumescence were also consistently higher than during the condition of non-REM without tumescence in the normal, but not in the impotent, group.

Adult↗

PubMed1993

Correlation of duplex sonography with arteriography in patients with erectile dysfunction.

OBJECTIVE: Our objective was to assess the accuracy of using measurements of peak systolic velocity in the cavernosal artery for the diagnosis of arteriogenic impotence. MATERIALS AND METHODS: Twenty consecutive men with erectile dysfunction had duplex sonography after intracavernosal injection of papaverine to induce an erection. Peak systolic velocities in the right and left cavernosal arteries were measured by using Doppler sonography. Right and left selective penile arteriography was performed with low-osmolality contrast media after intracavernosal injection of papverine and intraarterial tolazoline. On the basis of the angiographic findings, penile arterial function was classified as normal, moderately insufficient, or severely insufficient. Doppler measurements of peak systolic velocity were correlated with arteriographic results. RESULTS: All 11 cavernosal arteries with peak velocities less than 25 cm/sec were associated with arterial disease, nine severe and two moderate. Thirteen of 17 carvernosal arteries with peak systolic velocities 25-34 cm/sec were associated with arterial disease, five severe and eight moderate. Only one of the 12 cavernosal arteries with peak velocity at or greater than 35 cm/sec was associated with arterial disease. CONCLUSION: We conclude that peak systolic velocity in the cavernosal artery as measured on duplex sonography is an accurate predictor of arterial disease in patients with erectile dysfunction. A peak systolic velocity of at least 35 cm/sec indicates normal arterial supply. At peak systolic velocities less than 35 cm/sec, the likelihood and severity of arterial disease increase as the peak systolic velocity decreases, with a peak velocity less than 25 cm/sec indicating a high likelihood of severe arterial disease.

Adult↗

PubMed1998

Evidence based assessment of erectile dysfunction.

Do we need impotence testing? Yes, it is the clinician's obligation to establish the etiology of impotence: end organ vascular failure vs neurologic dysfunction vs psychosexual dysfunction, classify the severity of that dysfunction, and select a therapy that is not only acceptable to the patient but also addresses his pathology. The most commonly utilized diagnostic tests for erectile dysfunction are outlined in this monograph. Nocturnal erections are evaluated by tests commonly known as nocturnal penile tumescence (NPT) studies. NPT has been measured by each of the following methods: stamp test, Snap Gauges, strain gauges, NPTR (Rigiscan, Osbon Medical Systems), and sleep lab NPTR. Normal Nocturnal Penile Tumescence and Rigidity (NPTR) depends on both the integrity of the corticospinal efferents to the penis and vascular responsiveness of the penile tissues to those nerve signals. When nocturnal erections are of appropriate duration and strength the central and peripheral neuroeffectors and intra-corporal regulators of penile hemodynamics are intact. Unfortunately, abnormal NPTR is of little value in determining the etiology or classifying the severity of vascular impotence; the most prevalent kind of end organ failure. The sacral reflex arc of erection consists of somatosensory afferents via the dorsal and pudendal nerves and autonomic efferents via the pelvic and cavernous nerves. These afferents have been measured indirectly by somatosensory evoked potentials (SSEP) and bulbocavernosus reflex latency (BCR). Penile EMG's have recently been recorded, corporal cavernosal smooth muscle electrical activity: CC-EMG. This technology is far from standardized; computer-assisted interpretations of penile electrical potentials may eventually differentiate afferent nerve pathologies so long inferred in: diabetes, spinal cord injury and following radical pelvic surgery. Numerous diagnostic tests have been employed to evaluate penile hemodynamics: penile plethysmography, penile blood pressures, penile brachial index, selective internal pudendal pharmacoangiography, Doppler sonography, dynamic infusion cavernosometry/cavernosography, nuclear washout radiography, and color duplex Doppler ultrasound. Insufficient corporal veno-occlusion is implicated in up to 50% of patients. The diagnosis and demonstration of venous leakage requires complete smooth muscle relaxation. Veno-occlusive dysfunction is associated with poorly sustained erections; this pathology has traditionally been evaluated with Dynamic Infusion Cavernosometry and Cavernosography. DICC is an invasive test, and is now primarily reserved for patients considering the option of vascular reconstructive procedure. Pharmacotesting consists of intracavernous injection and visual rating of the subsequent erection; the test is the most commonly used office procedure for diagnosing erectile dysfunction. It is simple, minimally invasive, and performed without monitoring equipment. Hemodynamic investigations suggest that a positive injection test is associated with normal veno-occlusion, but not necessarily with normal arterial function. When the penile response to pharmacotesting is suboptimal or equivocal, diagnostic testing with duplex Doppler assessment should be performed. The penile blood flow study (PBFS) provides an objective, minimally invasive evaluation of a suboptimal/equivocal erectile response.

Animals↗

PubMed2004

[Erectile dysfunction. New drugs with special consideration of the PDE 5 inhibitors].

Erectile dysfunction (ED) tends to be associated with other diseases, the common basis of which is endothelial dysfunction. ED is also frequently combined with LUTS and the common basis for both conditions seems to be elevation of Rho-kinase activity and decrease of NO concentration. Because all three PDE 5 inhibitors sildenafil, tadalafil, and vardenafil have a common mode of action, i.e., inhibition of PDE 5, they are not different in terms of their efficacy and safety profile except for color vision disturbances which are more common after sildenafil and back pain/myalgia more often observed after tadalafil. The main differentiating characteristics among the three PDE 5 inhibitors are their pharmacokinetics. These are ultimately responsible for the observation that in head-to-head comparative trials depending on the respective study design the overwhelming majority of the patients opted either for tadalafil as the longest acting PDE 5 inhibitor (36 h) or for vardenafil as a relatively rapidly acting drug. All published studies so far have shown that in terms of the cardiovascular risk profile (myocardial infarction rate) all three PDE 5 inhibitors performed better than placebo although the results were not statistically significant. Without any exception it applies to all three PDE 5 inhibitors that they are absolutely contraindicated in patients taking nitrate- or molsidomine-containing medications and that they may interact in particular with non-uroselective alpha-adrenoceptor blockers. This is why their simultaneous application with PDE 5 inhibitors has to be avoided.In the near future chronic (daily) application of a PDE 5 inhibitor may show advantages, at least in those 50-60% of all patients in whom there is a high likelihood of endothelial dysfunction due to the diagnostic (penile duplex Doppler) outcome. Possible new developments in the management of ED with a time frame of 5-8 years until their market approval are guanylate cyclase activators, Rho-kinase inhibitors, melanocortin receptor agonists, gene therapy, and tissue engineering.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2005

Available and future treatments for erectile dysfunction.

There is now a range of treatments for patients with erectile dysfunction (ED) beyond the psychosexual counselling and surgical implants that were the only available management options for many years. Oral treatments, which are minimally invasive, are the favoured first-line option for treatments and include the phosphodiesterase-5 (PDE5) inhibitors, and dopamine agonists such as apomorphine. Psychosexual counselling may still be an appropriate treatment, on its own or in combination, in a minority of patients who do not respond to oral treatment, or where an origin for the ED is likely from the history. The PDE5 inhibitors, sildenafil, tadalafil, and vardenafil, have proven to be effective and well tolerated and facilitate erectile function. Apomorphine is also effective, but causes nausea in a minority of men. The alpha-receptor antagonist yohimbine has been found to be effective in some placebo-controlled trials, but its effectiveness is probably inadequate for treatment of most ED. Intracavernosal injection of drugs such as prostaglandin E1, papaverine, and phentolamine (sometimes in combination) is an effective but invasive treatment. Other treatments include testosterone, vacuum-pump treatment, surgery, and surgical implants, and tend to be used where patients do not respond to oral treatment and counselling.

Apomorphine↗

PubMed1995

Functional electromyostimulation of the corpus cavernosum penis--preliminary results of a novel therapeutic option for erectile dysfunction.

Transcutaneous application of low-frequency electric current in the treatment of partially or temporarily denervated striated muscles is widely used to prevent or treat muscular atrophy. Due to the high regenerative capacity of smooth-muscle cells, this approach should be beneficial in the treatment of diseases with smooth-muscle degeneration due to partial denervation. Our study was done to evaluate the possible beneficial effect of transcutaneously applied low-frequency electric current on the corpus cavernosum penis in the treatment of erectile dysfunction. After a comprehensive workup, 21 patients with chronic erectile dysfunction (20/21 vasoactive nonresponders) received daily (3-5 x 20 min) transcutaneous functional electromyostimulation of the corpus cavernosum smooth muscles [FEMCC; zero-line symmetric impulses of trapezoid shape, 2-channel device with alternating stimulations; frequency (f), 10-20 Hz for channel I and 20-35 Hz for channel II; impulse duration (ti), 100-150 microseconds; approx. 12 mA; rise time, 0.5 s; stimulation time, 5 s/channel; pause between stimulations, 0.5 s. In all, 4/21 patients (19%) regained full spontaneous erections and another 3/21 (14%) responded to vasoactive drugs after FEMCC. Overall, 14/21 were FEMCC failures, including 2 who subjectively "improved." In a similar group of patients who were evaluated during the same period but received no therapy, no spontaneous improvement in erectile function was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗