ASSESS-3: a randomised, double-blind, flexible-dose clinical trial of the efficacy and safety of oral sildenafil in the treatment of men with erectile dysfunction in Taiwan

Stem Cell and Gene-Based Therapy for Erectile Dysfunction: Current Status and Future Needs

Erectile dysfunction affects an increasing number of men. The mainstays of management include oral medications, local erectogenic agents, and surgical placement of prosthetic devices. Newer technologies such as stem cell and gene therapy have been investigated as a means to restore spontaneous erectile capacity. Mesenchymal stem cells are thought to produce a local immunomodulatory and pro-repair milieu at the area of injury or needed repair. Gene therapy involves targeting the erectogenic pathway to augment factors involved in producing a natural erection. Such therapies are considered experimental and should be used in the setting of a clinical trial with appropriate oversight.

Predictors of Erectile Function Normalization in Men With Erectile Dysfunction Treated With Placebo

BACKGROUND

Clinical study and practice data have shown sildenafil improves sexual function in men with erectile dysfunction (ED). However, some men treated with placebo in double-blind, placebo-controlled sildenafil studies also report improved erectile function as measured by International Index of Erectile Function (IIEF)-Erectile Function Domain (EFD) scores.

AIM

This analysis estimated the relationship between post-baseline IIEF-EFD scores and demographic variables, including co-morbidities, in men with ED receiving placebo in flexible-dose sildenafil studies.

METHODS

Placebo-treated participants in the intent-to-treat population of 42 double-blind, placebo-controlled, flexible-dose, sildenafil studies were included. A participant was classified as a placebo responder if the IIEF-EFD score was ≥26 at the last visit.

OUTCOMES

Variables assessed were age (<45, 45-64, ≥65 years), race, body mass index, co-morbidities (cardiovascular disease/hypertension, diabetes mellitus, depression), date the last study dose was taken, study completion date, ED etiology (psychogenic, organic, mixed), history of cigarette smoking, ED duration, baseline IIEF-EFD score (≤10, 11-16, ≥17), and treatment duration. Stepwise multivariate logistic regression models assessed the odds of being a responder vs a non-responder for each variable.

RESULTS

A total of 4,360 men were included; 13.5% were responders. Odds estimates indicated the largest likelihood of placebo response occurred in men who were black (odds = 20.2, P < .0001), were younger than 45 years (odds = 7.3, P < .0001), had mild ED (baseline IIEF-EFD ≥17; odds >100, P < .0001), and did not have diabetes (odds = 4.5, P < .0001). The likelihood of a placebo response decreased as ED duration increased (odds = 0.74, P < .0001). The frequency of common adverse events was similar between placebo responders and non-responders.

CLINICAL TRANSLATION

These findings contribute to the improved understanding of predictors of placebo response in sildenafil clinical studies. Elucidation of these factors may contribute to the development of further interventions and treatment strategies and best practices for clinical trials.

STRENGTHS AND CONCLUSIONS

Strengths of this analysis include the large and diverse population and the duration of follow-up. Limitations include those associated with retrospective analyses and the inability to ascertain to what extent other demographic factors might have contributed to the placebo responses or how these placebo responses might be related to the natural course of ED.

CONCLUSIONS

Certain demographics, co-morbidities, and condition characteristics predicted the odds of a placebo response in sildenafil clinical studies of ED. Underlying reasons behind a placebo response warrant further evaluation. Mulhall JP, Carlsson M, Stecher V, et al. Predictors of Erectile Function Normalization in Men With Erectile Dysfunction Treated With Placebo. J Sex Med 2018;15:866-872.

Ethnicity and age as factors in sildenafil treatment of erectile dysfunction

INTRODUCTION

Sildenafil has been evaluated in >16 000 men with erectile dysfunction (ED) in double-blind, placebo-controlled trials.

AIM

To assess efficacy and safety of sildenafil in ED by ethnicity (white, black Asian) and age (≤45, 46-60, ≥61 years).

METHODS

Data were pooled from 38 double-blind, placebo-controlled, flexible-dose trials. Most had starting sildenafil doses of 50 mg once daily, ~1 hour before sexual activity, with adjustment to 100 or 25 mg as needed.

MAIN OUTCOME MEASURES

Change from baseline in International Index of Erectile Function erectile function (IIEF-EF) domain score assessed with analysis of covariance and a Global Assessment Question (GAQ; "Did the treatment improve your erections?") at endpoint assessed with logistic regression analysis.

RESULTS

4120 and 3714 men received sildenafil and placebo, respectively (2740 and 2671 White; 407 and 385 Black; 973 and 658 Asian). For sildenafil vs. placebo groups, overall treatment differences for IIEF-EF domain and GAQ were significant for each ethnic and age group (P<.0001); significant treatment-by-ethnicity and treatment-by-age interactions were also observed for change in IIEF-EF domain scores (P<.05), with differences significantly greater for White vs. Black (P<.0001), White vs. Asian (P=.0163), and Asian vs. Black (P=.0036) men. A significant treatment-by-ethnicity interaction was observed for GAQ (P=.0004). The OR comparison for GAQ was significantly greater (P=.0001) with sildenafil vs. placebo in White (OR=11.2) or Asian (OR=12.4) men vs. Black men (OR=5.1). Adverse-event rates were generally similar, with some age variations.

CONCLUSIONS

Sildenafil is effective and well-tolerated regardless of ethnicity or age; however, treatment effects can vary.

Medical management of erectile dysfunction in aging males: is it too late to treat?

Erectile dysfunction (ED) is a common disorder among aging males. However, most aging males refuse to seek medical help and believe that ED is an irreversible event in the aging process. The purpose of this study was to describe the current medical management of ED in aging males and to examine whether it is too late to treat this disorder in these elderly men. From 2007 to 2008, 4507 patients diagnosed with ED were gathered from 46 centers in China; 4241 completed the study, 3837 of whom were treated with sildenafil. The 3837 patients were divided into five groups based on age (group A: 20–30 years; group B: 31–40 years; group C: 41–50 years; group D: 51–60 years; and group E: >60 years). After comparing pre- and posttreatment International Index of Erectile Function-Erectile Function domain (IIEF-EF) questionnaires, Erection Hardness Scale (EHS), and IIEF Q13 (“How satisfied have you been with your overall sex life?”), we discovered that the aging males had worse erectile function, erection hardness, and sexual satisfaction than the younger males (P < 0.001). After treatment, the improvement rates in the IIEF-EF, EHS, and IIEF Q13 scores were 107.0%, 83.1%, and 116.5%, respectively. The magnitude of these changes demonstrated significant differences among groups (P < 0.001). Accordingly, aging males are likely to benefit more from medical treatment. We propose that aging males should be informed that age is not a limiting factor for medical ED management, and it is never too late to treat.

Sildenafil: two decades of benefits or risks?

Sildenafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE-5). A patent was registered for this drug in 1990, which expired in 2010. Since expiration, the drug has been marketed under various trade names or as generic drugs. Numerous clinical trials have been conducted addressing the effectiveness of the drug for erectile dysfunction (ED) and its safety regarding the presence or absence of specific comorbidities. After over 20 years in the market, we need to ask: has the scientific community reached a general consensus as to the overall efficacy and safety of the drug? Can we firmly state that the benefits of the drug outweigh its risks? This review suggests that sildenafil is an effective and easily manageable treatment for erectile dysfunction, both in the absence and in the presence of comorbidities. After two decades of the emergence of sildenafil as a drug of choice for the treatment of ED (and the numerous studies and clinical trials undertaken during this time span), it is now possible to state that the benefits of the drug do outweigh the risks, and represent an significant improvement in the quality of life in men with ED.

Dapoxetine, a novel selective serotonin transport inhibitor for the treatment of premature ejaculation

Premature ejaculation (PE) is the most common male sexual disorder, estimated to affect up to 30% of men. Over the past one or two decades, clinical investigators have participated in an increasing number of studies that are helping in our understanding of PE, which will undoubtedly facilitate future treatments. Apart from a number of behavioral approaches, the treatment of PE consists of primarily off-label use of oral selective serotonin reuptake inhibitors (SSRIs) via either on-demand or daily delivery. However, various undesirable side-effects of these medications have led researchers to search for and develop new therapeutic approaches for PE. Dapoxetine is a short-acting SSRI developed specifically for the treatment of PE. Early trials with dapoxetine have documented successful outcomes without serious short- or long-term side-effects. This review addresses the definition, classification, diagnosis, physiology, and neurobiopathology of PE, and evaluates therapeutic strategies with novel treatments for PE.

Male sexual dysfunction in Asia

Sex has always been a taboo subject in Asian society. However, over the past few years, awareness in the field of men's sexual health has improved, and interest in sexual health research has recently increased. The epidemiology and prevalence of erectile dysfunction, hypogonadism and premature ejaculation in Asia are similar in the West. However, several issues are specific to Asian males, including culture and beliefs, awareness, compliance and the availability of traditional/complementary medicine. In Asia, sexual medicine is still in its infancy, and a concerted effort from the government, relevant societies, physicians and the media is required to propel sexual medicine to the forefront of health care.

Prevalence and medical management of erectile dysfunction in Asia

Erectile dysfunction (ED) is an important worldwide health issue that has a significant negative impact on the quality of life and life satisfaction of both the affected individual and his partner. Here we review the prevalence of ED in Asia, associated factors that may influence sexual attitudes and sexual behaviours, and randomized clinical trials (RCTs) of phosphodiesterase-5 (PDE-5) inhibitors to evaluate the clinical efficacy and safety of PDE-5 inhibitors in Asian men. We searched for English-language articles in MEDLINE and PubMed from January 2000 to September 2010. Our results showed that the overall reported prevalence rate of ED in Asia ranged widely, from 2% to 88%. This finding indicates that ED is a common and major health problem in this region. However, sociocultural and economic factors in Asia prevent people from seeking and obtaining appropriate medical care. We found reports on five kinds of PDE-5 inhibitors for the management of ED: sildenafil, vardenafil, tadalafil, udenafil and mirodenafil. The results of RCTs showed that these five PDE-5 inhibitors are more effective than placebo in improving erectile function in Asian men with ED and that these drugs have similar efficacy and safety profiles.

Safety of sildenafil citrate: review of 67 double-blind placebo-controlled trials and the postmarketing safety database

AIM

To review special safety topics associated with sildenafil and to document the tolerability of 50- and 100-mg doses, overall and by age, in men with erectile dysfunction (ED).

METHODS

Data were collated from 67 double-blind placebo-controlled (DBPC) trials (> 14,000 men) conducted by the manufacturer and from the manufacturer's postmarketing safety database (39,277 patients). The DBPC data were stratified by dose, starting dose and age (> or = 65 and > or = 75 years). Special safety topics included cardiovascular risk, priapism, non-arteritic anterior ischaemic optic neuropathy (NAION), impaired renal and hepatic function, drug interactions (i.e. nitrates, cytochrome P3A4 inhibitors, other ED therapies and alpha-blockers) and incorrect use.

RESULTS

Sildenafil was well tolerated at a dose of 50 or 100 mg in men with ED, overall, in those aged > or = 65 years, and in those aged > or = 75 years. Analyses of the databases did not reveal any causal link between sildenafil and cardiovascular events, or any new safety risks relating to cardiovascular events, priapism, NAION, hearing loss or drug interactions. In the small number of men with moderate impairment of renal function or hepatic function who were treated with sildenafil in DBPC trials, the safety profile was similar to that in men with no impairment of renal or hepatic function. Overdose with sildenafil was rare in the ED population. No new safety issues, emerging trends or adverse reactions were identified in conjunction with overdose, dependence, abuse or misuse.

CONCLUSION

This collated review confirms generally the good tolerability and established safety profile of sildenafil 50 and 100 mg in men with ED and reveals no new safety issues.

Erectile dysfunction and lower urinary tract

During the last decades it turned out that the NO/cGMP signaling cascade is one of the most prominent regulators of a variety of physiological and pathophysiological processes in a broad range of mammalian tissues. Thus cGMP is a key second messenger and targeting this pathway by increasing intracellular cGMP levels is a very successful approach in pharmacology as shown for nitrates, PDE5 inhibitors and more recently for stimulators of the guanylate cyclase. Besides the beneficial effects of cGMP elevation in cardiac, vascular, pulmonary, renal or liver disorders the launch of PDE5 inhibitors for the treatment of erectile dysfunction 10 years ago, has directed a lot of attention to the NO/cGMP signaling in the lower urinary tract. Triggered by the use of PDE5 inhibitors in ED it turned out that cGMP is a common regulatory mechanism for lower urinary tract function also beyond ED. In recent years intense research and development efforts were undertaken to elucidate the role of the NO/cGMP and to fully exploit the therapeutic implications of cGMP elevation in urological disorders in ED and beyond. Therefore we have summarized the effects of cGMP elevation for treatment of erectile dysfunction in males and in females. We have also reviewed the recent pre-clinical and clinical lines of evidence for treatment options of benign prostatic hyperplasia and lower urinary tract symptoms in male patients and overactive bladder and urinary incontinence in female patients. In addition we also touch more speculative concepts using cGMP elevating drugs for the treatment of premature ejaculation, peyornies disease and stone disease.

Interventions for sexual dysfunction following treatments for cancer

BACKGROUND

The proportion of people living with and surviving cancer is growing. This has led to increased awareness of the importance of quality of life including sexual function in people with cancer. Sexual dysfunction (SD) is a potential long-term complication of cancer treatments.

OBJECTIVES

Evaluate effectiveness of interventions for SD following treatments for cancer and their adverse effects.

SEARCH STRATEGY

The Cochrane Pain, Palliative & Supportive Care Register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, PsycInfo, AMED, CINAHL, Dissertation Abstracts and NHS Research Register were searched.

SELECTION CRITERIA

Randomised controlled trials (RCTs) were included that assessed the effectiveness of a treatment for SD. The trial population comprised of adults of either sex who at trial entry had developed SD as a consequence of cancer treatment.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data and assessed trial quality. Meta-analysis was considered for trials with comparable key characteristics.

MAIN RESULTS

Eleven RCTs with a total of 1743 participants were identified. The quality of the trials was poor. Ten trials explored interventions for SD in men following treatments for non-metastatic prostate cancer. One trial explored effectiveness in women of a lubricating vaginal cream following radiotherapy for cervical cancer. The strongest evidence (from four trials) was on oral phosphodiesterase type 5 (PDE5) inhibitors for erectile dysfunction (ED) following radiotherapy of the prostate or radical prostatectomy. The results using validated measures in all trials significantly favoured those in the PDE5 inhibitor group(s). The combined results of two trials indicated a significantly greater improvement in ED in the PDE5 inhibitor groups (odds ratio (OR) 10.09 95% confidence interval (CI) 6.20 to 16.43). Negative effects were few and usually mild to moderate headaches or flushing. One trial reported more clinically serious events including six events of tachycardia and six of chest pain. Following prostate cancer treatments there was some evidence that PDE5 inhibitors are more effective in combination with acetyl-L-carnitine and propionyl-L-carnitine and that sexual counselling improves self-administration of prostaglandin intra-cavernous injection for SD. There was some evidence following treatment for prostate cancer that transurethral alprostadil and vacuum constriction devices reduce SD, although in both trials negative effects were fairly common. There is some evidence that vaginal lubricating creams reduce SD.

AUTHORS' CONCLUSIONS

PDE5 inhibitors are an effective treatment for SD secondary to treatments for prostate cancer. Other interventions identified need to be tested in further RCTs. The SD interventions in this review are not representative of the range available for men and women. Further evaluations are needed for these interventions for SD following cancer treatments.

The Efficacy and Safety of Vardenafil in East Asian Men with Erectile Dysfunction

INTRODUCTION

Previous clinical studies assessing the efficacy and safety of vardenafil, an oral phosphodiesterase type 5 inhibitor, in men with erectile dysfunction (ED) have consisted mostly of Caucasian patients.

AIM

The aim of this article is to describe the efficacy and safety of vardenafil in men of East Asian ethnicity with ED.

METHODS

Data were pooled from two 12-week, double-blind studies that included 306 East Asian men randomized to placebo or 10 mg of vardenafil.

MAIN OUTCOME MEASURES

Efficacy variables included the International Index of Erectile Function-erectile function (IIEF-EF) domain score, questionnaires of Sexual Encounter Profile (SEP2 and SEP3), and a Global Assessment Question (GAQ). Safety assessments included laboratory tests, vital signs, 12-lead electrocardiogram recordings, and patients' reporting of adverse events.

RESULTS

A total of 306 East Asian men with ED were treated with placebo (N = 151) or vardenafil (N = 155). Mean baseline IIEF-EF domain scores (placebo, 13.4; vardenafil, 14.2) were consistent with moderate ED. At end point, the patients treated with vardenafil had a significantly greater increase in IIEF-EF domain score compared with placebo (24.2 vs. 15.9; P < 0.0001). The average per patient penetration (SEP2) success rate was significantly higher in the vardenafil group compared with placebo (88% vs. 58%; P < 0.0001). Moreover, the average per patient intercourse completion (SEP3) success rate was significantly higher in the vardenafil group compared with placebo (69% vs. 23%; P < 0.0001). Positive GAQ responses were reported by 85% of patients receiving vardenafil, compared with 33% of those receiving placebo. The most frequent adverse events were vasodilatation (primarily facial flushing), rhinitis, and headache, all of which were of mild intensity.

CONCLUSIONS

Vardenafil is an effective, well-tolerated oral drug for the treatment of East Asian men with moderate ED of broad-spectrum etiology.

Sildenafil citrate for erectile dysfunction in men with diabetes and cardiovascular risk factors: a retrospective analysis of pooled data from placebo-controlled trials

OBJECTIVE

Cardiovascular (CV) risk factors are associated with an increased risk of erectile dysfunction (ED). In men with diabetes mellitus (DM), pooled from clinical trials of sildenafil treatment for ED, this retrospective analysis determined efficacy and safety, overall and in subgroups with additional CV risk (i.e., hypertension, dyslipidemia, and smoking).

RESEARCH DESIGN AND METHODS

From the manufacturer's database of worldwide research, 12-week data from men with DM were pooled from randomized, double-blind, placebo-controlled trials of flexible-dose sildenafil (25, 50, or 100 mg, PRN) for ED.

MAIN OUTCOME MEASURES

Question 3 (achieving an erection), question 4 (maintaining an erection), and the Erectile Function domain of the International Index of Erectile Function; percentage of successful intercourse attempts according to patient event logs; and response to a global efficacy question (GEQ). Differences between groups were determined using logistic regression (percentage of responders according to GEQ) and analysis of covariance (all other outcomes).

RESULTS

Inclusion criteria were met by 11 trials and by 974 men with DM and ED who were randomized to placebo (n = 482) and sildenafil (n = 492) within the selected trials. For all outcomes, overall and regardless of additional CV risk, the benefit was greater for sildenafil versus placebo (p < or = 0.0001), including 3-fold more men responding that sildenafil treatment improved their erections (62% vs. 18%) and a more than doubling of the mean +/- standard error percentage of successful sexual intercourse attempts (52.6 +/- 5.0 vs. 22.4 +/- 5.1). Adverse events were mild to moderate and included (sildenafil vs. placebo) headache (5% vs. 2%), flushing (7% vs. 2%), and dyspepsia (4% vs. 0%), which is consistent with the profile in the general population of men treated with sildenafil for ED.

CONCLUSION

This retrospective analysis of pooled data showed that sildenafil was well tolerated and improved erectile function and intercourse success in men with ED and DM, regardless of additional CV risk factors.

Efficacy and safety of on demand tadalafil in the treatment of East and Southeast Asian men with erectile dysfunction: a randomized double-blind, parallel, placebo-controlled clinical study

AIM

To assess the efficacy and safety of tadalafil in comparison to a placebo, when taken on demand for 12 weeks by East/Southeast Asian men with erectile dysfunction (ED).

METHODS

This multicenter, randomized, double-blind, parallel group, placebo-controlled study was conducted at 17 centers across East and Southeast Asia between August 2002 and February 2003. Men more than 18 years of age with mild to severe ED of various etiologies were randomized to receive a placebo or 20 mg of tadalafil taken as needed (maximum once daily). Efficacy assessments included the International Index of Erectile Function, the Sexual Encounter Profile diary and Global Assessment Questions.

RESULTS

Tadalafil significantly improved erectile function as compared to the placebo (P < 0.001). At the endpoint, the patients receiving 20 mg of tadalafil reported a greater mean per patient percentage of successful intercourse attempts (Sexual Encounter Profile question 3: 70.9% compared to 33.5% in the placebo) and a greater proportion of improved erections (Global Assessment Question: 86.2% compared to 30.1%). Most (= or < 3%) treatment emergent adverse events were mild or moderate. The most common treatment emergent adverse events were headache, back pain, dizziness and dyspepsia.

CONCLUSION

Tadalafil was an effective and well-tolerated treatment for ED in East and Southeast Asian men.

Efficacy and safety of on-demand tadalafil for the treatment of erectile dysfunction in South-East Asian men

AIM

Tadalafil is an inhibitor of phosphodiesterase type 5 used for the treatment of erectile dysfunction (ED). The efficacy and safety of tadalafil have been evaluated extensively in Western populations. Our aim was to assess the efficacy and safety of on-demand tadalafil for the treatment of ED in South-East Asian men.

METHODS

This was a randomized, double-blind, placebo-controlled study of men with mild to severe ED of various etiologies randomized to receive placebo (n = 122), tadalafil 10 mg (n = 120), or tadalafil 20 mg (n = 125), taken as needed (maximum once daily) for 12 weeks. Efficacy assessments included the International Index of Erectile Function (IIEF), the Sexual Encounter Profile (SEP) diary, and a Global Assessment Question (GAQ).

RESULTS

Men from China, Singapore, and the Philippines participated in this trial (n = 367). Compared with placebo, tadalafil significantly improved erectile dysfunction on all efficacy outcomes (P < 0.001). Patients receiving tadalafil 10 mg and 20 mg experienced a significant mean improvement of 8.1 and 8.7, respectively, in the IIEF Erectile Function (IIEF-EF) domain score from baseline (vs placebo 2.4, P < 0.001). In patients receiving tadalafil 10 mg and 20 mg, the mean per-patient success rate for intercourse attempts (SEP3) was 62% and 70%, respectively, compared with 32% for the placebo group (P < 0.001). Of patients who received tadalafil 10 mg and 20 mg, 81% and 86% reported improved erections at endpoint (GAQ) compared with 44% in the placebo group (P < 0.001). The most common adverse events reported by patients were headache, back pain, dyspepsia, and dizziness.

CONCLUSIONS

Tadalafil was an effective and well-tolerated treatment for South-East Asian men with ED.

Sildenafil citrate (Viagra) treatment for erectile dysfunction: An updated profile of response and effectiveness

In the 7 years since sildenafil citrate (VIAGRA) was introduced as the first oral phosphodiesterase type 5 inhibitor therapy for erectile dysfunction, it has been used to treat nearly 27 million men with erectile dysfunction worldwide. Patient populations with erectile dysfunction of varying etiologies and with diverse comorbidities have benefited from sildenafil treatment. This update focuses on relatively recent research that further defines the response and effectiveness profiles of sildenafil and provides additional insight into optimizing treatment. In addition to providing recent data on sildenafil efficacy and safety/tolerability, the update provides data on assessments of erection hardness, measures of psychosocial outcomes (e.g., emotional well-being and treatment satisfaction), and treatment approaches to maximize response and effectiveness (e.g., by titrating to the maximum tolerated dose). Increased understanding of the sildenafil response and effectiveness profiles and optimal sildenafil treatment are central to the appropriate management of erectile dysfunction using sildenafil.

A meta-regression analysis of treatment effect modifiers in trials with flexible-dose oral sildenafil for erectile dysfunction in broad-spectrum populations

Several trials and reviews provide evidence for the efficacy of phosphodiesterase-5 inhibitors in the treatment of erectile dysfunction (ED). However, little is known about the impact of treatment effect modifiers other than concomitant diseases. Our objective was to identify patient and trial characteristics as well as methodological and publication-related issues that are associated with the treatment effect measured in flexible-dose randomized controlled trials of oral sildenafil for ED. The MEDLINE and the Cochrane Central databases were searched for efficacy trials of sildenafil. Thirteen trials fulfilled all inclusion criteria. A series of meta-regression and graphical analyses were performed to test the impact of possible effect modifiers. Treatment effect was influenced by mean baseline disease severity and mean duration of the disease. These associations were at least partly mediated by placebo response. Trial duration, age of patients and etiology of ED in patients did not have any significant influence on the treatment effect. The year of publication of primary trials was also related to trial findings. Our analysis adds important data to enable the control of confounding variables in future trials and meta-analyses. It might also help the individual to assess the unbiased efficacy and true innovative potential of available and forthcoming pharmacological agents.

Herbal medicine research in Taiwan

Of all the countries in the world, why did you choose Taiwan to pursue your study? It is a question that I (comments of the first author) have answered a thousand times. My first visit to a laboratory at National Taiwan University opened my eyes to the possibilities of herbal medicine research, especially in the area of veterinary medicine. It became my ambition to link the knowledge of Traditional Chinese Medicine (TCM) and Ayurveda from the Indian subcontinent and their integration with other systems of medicine, including Western medicine (WM), to achieve the concept of Sustainable Medicine, firstly for animals and then for humans. The Ministry of Economic Affairs (MOEA) has implemented a technology development program to quickly establish the key technologies, and this is a moment of opportunity for Taiwan's traditional herbal medicine industry to upgrade and transform itself. This paper, initially intended to be a student's narration, has evolved into a multi-author treatise on the present state and likely future scenario of herbal medicine research in Taiwan.

Effect of Epimedium brevicornum Maxim extract on elicitation of penile erection in the rat

OBJECTIVES

To investigate the effect and mechanism of a Chinese medicine (Epimedium brevicornum Maxim [EbM]) on elicitation of penile erection in the rat.

METHODS

Adult male Sprague-Dawley rats were used. The penile intracavernous pressure (ICP) was monitored. Intracavernous administration of different doses (30, 100, 300, 1000, 3000, 6500, and 10,000 microg/0.1 mL) of EbM extract and saline 0.1 mL was done. Intracavernous NG-nitro-L-arginine methyl ester (L-NAME) (120 microg) was administered, followed by EbM extract 300 microg 10 minutes later. EbM extract (20, 10, and 10 microg) was stereotaxically delivered into the intracerebral ventricle, paraventricular nucleus of the hypothalamus, and hippocampus, respectively.

RESULTS

After intracavernous administration of 30 or 100 microg EbM extract, no significant change in ICP was noted. All other doses (300 to 10,000 microg) of EbM extract elicited a significant increase in ICP, with the greatest peak at 99.7 +/- 0.3 mm Hg (resting 7.8 +/- 1.0 mm Hg) after application of 6500 microg EbM extract. No change in ICP occurred with administration of L-NAME followed by EbM extract. Furthermore, intracavernous saline or administration of EbM extract into the intracerebral ventricle, paraventricular nucleus of the hypothalamus, or hippocampus was ineffective in inducing a significant change in ICP.

CONCLUSIONS

These results suggest that intracavernous administration of EbM extract may elicit penile erection in the rat. Nitric oxide may be involved in this penile erection-inducing effect. No central neural effect of EbM extract may exist in the elicitation of penile erection.

Epimedium brevicornum Maxim extract relaxes rabbit corpus cavernosum through multitargets on nitric oxide/cyclic guanosine monophosphate signaling pathway

Epimedium brevicornum Maxim (EbM) has been reputed to have sexual stimulation effects on males. The study is aimed to test the hypothesis that EbM extracts relaxed the corpus cavernosum (CC) smooth muscle through activation of multitargets on nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling pathway. Water extract of EbM and its subfraction (EP-20) were prepared and standardized by high-performance liquid chromatography. Isolated rabbit CC strips were mounted in organ baths and isometric tension was recorded in the presence or absence of specific inhibitors related to NO/cGMP signaling such as L-N(G)-nitro-arginine methyl ester (L-NAME), 1H-[1,2,4]oxadiazolo-[4,3-a] quinoxalin-1-one (ODQ, a guanylyl cyclase inhibitor) or phosphodiesterase 5 (PDE 5) inhibitors. cGMP level was determined in EP-20-treated CC strips. The results showed that EP-20 enriched the content of L-arginine in the process of purification and relaxed the CC smooth muscle precontracted with phenylephrine (PE, 1 microM) in a concentration-dependent manner. Besides, EP-20 increased the amount of cGMP production in rabbit CC tissues. Coincubation with EP-20 and L-NAME or ODQ significantly decreased EP-20-induced relaxation whereas EP-20 increased sodium nitroprusside-induced relaxation in PE-precontracted CC strips. Besides, EP-20 increased the potency and the duration of the relaxation effects caused by electrical field stimulation. Finally, EP-20 could potentiate PDE 5 inhibitors in relaxation of PE-precontracted CC strips. We concluded that extract of EbM relax the CC smooth muscle through multitargets in NO/cGMP/PDE 5 pathway and might bring into perspective the treatment strategy for those patients with erectile dysfunction.

Indirect comparison of interventions using published randomised trials: systematic review of PDE-5 inhibitors for erectile dysfunction

BACKGROUND

There are no randomised and properly blinded trials directly comparing one PDE-5 inhibitor with another in a normal home setting. Valid indirect comparisons with a common comparator must examine equivalent doses, similar duration, similar populations, with the same outcomes reported in the same way.

METHODS

Published randomised, double-blind trials of oral PDE-5 inhibitors for erectile dysfunction were sought from reference lists in previous reviews and electronic searching. Analyses of efficacy and harm were carried out for each treatment, and results compared where there was a common comparator and consistency of outcome reporting, using equivalent doses.

RESULTS

Analysis was limited by differential reporting of outcomes. Sildenafil trials were clinically and geographically more diverse. Tadalafil and vardenafil trials tended to use enriched enrollment. Using all trials, the three interventions were similar for consistently reported efficacy outcomes. Rates of successful intercourse for sildenafil, tadalafil and vardenafil were 65%, 62%, and 59%, with placebo rates of 23-28%. The rates of improved erections were 76%, 75% and 71%, respectively, with placebo rates of 22-24%, and NNTs of 1.9 or 2.0. Reporting of withdrawals was less consistent, but all-cause withdrawals for sildenafil, tadalafil and vardenafil were 8% 13% and 20%. All three drugs were well tolerated, with headache being the most commonly reported event at 13-17%. There were few serious adverse events.

CONCLUSION

There were differences between trials in outcomes reported, limiting comparisons, and the most useful outcomes were not reported. For common outcomes there was similar efficacy between PDE-5 inhibitors.

Phosphodiesterase type 5 inhibitors for erectile dysfunction

The cyclic nucleotide signalling pathway mediates the smooth-muscle relaxing effects of nitric oxide necessary for normal erectile function. Down-regulation of this pathway is central to the pathophysiology of many forms of erectile dysfunction (ED), which is often associated with other chronic diseases (e.g. hypertension, type 2 diabetes mellitus) and treatments (e.g. certain drugs, radical prostatectomy). Conversely, selective inhibition of the enzyme that catalyses the degradation of cGMP (phosphodiesterase type 5, PDE-5) promotes erectile responses to sexual stimulation. The successful launch and commercialization of the selective PDE5 inhibitor (PDE5I) sildenafil transformed the treatment of ED, not only by providing an effective, well tolerated oral ED therapy, but also by fostering greater candour about the problem among men. Sildenafil is highly effective in promoting erectile responses across a wide spectrum of severity and causes of ED, including patients with ED that is often refractory to treatment. The recent advent of vardenafil, which has the highest in vitro potency of all available PDE5Is, and tadalafil, which has a prolonged half-life that may enable couples to have sexual activity with less planning, represent further advances. Other PDE5Is offering further potential improvements are under active investigation.

Efficacy and Safety of On‐Demand Oral Tadalafil in the Treatment of Men with Erectile Dysfunction in Taiwan: A Randomized, Double‐Blind, Parallel, Placebo‐Controlled Clinical Study

INTRODUCTION

Tadalafil is a phosphodiesterase type 5 inhibitor for the treatment of erectile dysfunction (ED). Past clinical trials have assessed its efficacy and safety in western populations. Tadalafil has not been investigated in a large clinical trial with a South-east Asian population.

AIM

To assess the efficacy and safety of on-demand tadalafil for the treatment of ED in a 12-week, double-blind, placebo-controlled study in Taiwan.

METHODS

Men with mild to severe ED of various etiologies were randomized to receive placebo, tadalafil 10 mg, or tadalafil 20 mg, taken as needed (maximum once daily). Efficacy assessments included the International Index of Erectile Function, the Sexual Encounter Profile (SEP) diary, and a Global Assessment Question (GAQ).

RESULTS

Tadalafil significantly improved erectile function compared with placebo (P < 0.005, all measures). At endpoint, the patients receiving tadalafil reported a greater mean per-patient percentage of successful intercourse attempts (SEP question 3: 70.0%, 10 mg; 78.0%, 20 mg) than placebo-treated patients (42.8%) and a greater proportion of improved erections (GAQ: 92.3% and 84.6% vs. 54.5%). Most treatment-emergent adverse events were mild or moderate. The most common adverse events were back pain, dyspepsia, and myalgia.

CONCLUSIONS

Tadalafil was an effective, well-tolerated therapy for men in Taiwan with ED of broad-spectrum severity and etiology.

What to learn about sildenafil in the treatment of erectile dysfunction from 3-year clinical experience

We retrospectively assessed the clinical uses and results of sildenafil in the treatment of erectile dysfunction (ED) in daily clinical practice from a cohort of 1658 subjects at a multispecialty medical center from 1999 to 2001 through a chart review, mailed questionnaire and telephone interview. The overall follow-up rate was 77.8% (1290/1658). The mean age was 63.8 y and ED duration was 3.4 y, and 44.6% of them had one or more concomitant conditions. The mean score of the International Index of Erectile Function erectile function domain was 12.7 in 314 nonselective subjects, and 75% of them had moderate to severe ED. The average number of purchase-visits and tablets of sildenafil purchased was 2.27 and 10.8 per person, respectively, and the prescription refill rate was 58.6%. Urology accounts for 91.4% of the specialties of prescribers. The response rate was 72.0%, which was significantly lower in subjects with diabetes, ischemic heart disease and following radical pelvic surgery than those without. Subjects with psychogenic etiology had the highest response rate, while those following radical pelvic surgery the lowest. Of the nonresponders, 67% did not try the maximum dose of 100 mg and 71.1% bought no more than four tablets. Adverse events were reported in 20.1% of the subjects. No one discontinued the treatment because of the adverse events. Mortality occurred in 17 subjects and none was considered related to sildenafil use. In conclusion, sildenafil was effective and safe in the treatment of ED in clinical practice. Compared with clinical trials or prospective clinical practice based studies, lack of dose titration, less follow-up visits and inadequate attempts before giving up were the main shortfalls in daily practice.

A comparative study of Ferula hermonis root extracts and sildenafil on copulatory behaviour of male rats

The effect of 600 mg/kg given by oral route to rats of Ferula hermonis roots extracts (petroleum ether, ethyl acetate, methanol and water) was evaluated on sexual behaviour of male rats. Petroleum ether and ethyl acetate extracts produced a significant decrease in both the mount rate (MR) and the intromission rate (IR), significant prolongation of intromission latency (IL) was observed when these extracts were compared with both controls and sildenafil. Methanolic extract produced a significant increase in MR while no effect has been observed on IR or IL in comparison with control. The effect of water extract was not significantly different from controls for the MR and IR, but there was a significant prolongation in the IL.

Efficacy and safety of sildenafil citrate (Viagra) in black and Hispanic American men

The objective of this study was to assess the efficacy and safety of sildenafil citrate (Viagra) in black American and Hispanic American men with erectile dysfunction (ED) of broad-spectrum etiology. A total of 246 black American and 197 Hispanic American men were randomized to sildenafil (50 mg, adjustable to 25 mg or 100 mg, depending on efficacy and tolerability; n = 124 and n = 99, respectively) or matching placebo (n = 122 and n = 98, respectively). After 6 weeks, patients were given the option of switching to the other blinded treatment for the following 6 weeks. The 12 weeks of double-blind treatment were followed by 12 weeks of open-label extension. Despite differences in prevalence of hypertension, diabetes mellitus, hyperlipidemia, and use of concomitant antihypertensive agents between the 2 study groups, sildenafil was efficacious and well tolerated. After 6 weeks, scores for questions 3 and 4 from the International Index of Erectile Function (IIEF) were significantly higher among sildenafil-treated black and Hispanic patients than in placebo-treated patients. In addition, compared with placebo, a significantly larger proportion of sildenafil patients reported improved erections and improved ability to have sexual intercourse. When efficacy results were stratified by ED severity or number of risk factors, scores for IIEF questions 3 and 4 were lower in men with severe ED versus mild-to-moderate ED. Similarly, the percentage of patients reporting improved erections decreased with ED severity and number of risk factors. The proportion of patients switching to the other treatment after 6 weeks was significantly higher in the placebo group (71% to 85%) than in the sildenafil group (27% to 28%). The most common adverse events included headache and vasodilation, which were mild to moderate in nature and were comparable between groups. These data demonstrate that despite differences in prevalence rates of comorbidities, efficacy and safety of sildenafil is maintained across different ethnic groups.