Double-blind trial of yohimbine in treatment of psychogenic impotence

Dietary Supplements for Erectile Dysfunction: Analysis of Marketed Products, Systematic Review, Meta-Analysis and Rational Use

The use of nutraceutical products to enhance male sexual performance has a long history, especially with regard to the treatment of erectile dysfunction (ED). Alternative treatments for ED are becoming increasingly popular, with growing interest from consumers, as well as increased revenue for manufacturers. Dietary supplements (DSs), which are a mixture of active ingredients, are mainly sold online. In randomized controlled trials, the molecules contained in DSs have demonstrated varying degrees of effectiveness, or even have no evidence to support their use. However, none of the studies carried out provided sufficient evidence to consider these products a first-line therapy. Therefore, the combination of the various active ingredients, especially in relation to the daily dose, leaves doubts about the real effectiveness. In order to evaluate the potential efficacy of DS formulations, we analyzed the products marketed in Italy using a scoring approach. A systematic review of the literature was performed to evaluate the effect of DS and to detect the active ingredients able to improve erectile function-called effective ingredients (EIs)-and their minimal effective daily dose (mED). A metanalysis identified some nutraceuticals, such as Panax ginseng, Tribulus terrestris and L-arginine, that are able to improve male sexual function. Based on the scoring system, 2 (8%) supplements matched with the cluster of higher expected efficacy, 3 (12%) with the lower efficacy cluster and 20 (80%) matched with the criterion of no expected efficacy. DSs marketed in Italy are usually blends of many substances that are frequently employed at a negligible dose or without any evidence.

Phytochemical Profiles and Biological Studies of Selected Botanical Dietary Supplements Used in the United States

Based on their current wide bioavailability, botanical dietary supplements have become an important component of the United States healthcare system, although most of these products have limited scientific evidence for their use. The most recent American Botanical Council Market Report estimated for 2020 a 17.3% increase in sales of these products when compared to 2019, for a total sales volume of $11,261 billion. The use of botanical dietary supplements products in the United States is guided by the Dietary Supplement Health and Education Act (DSHEA) from 1994, enacted by the U.S. Congress with the aim of providing more information to consumers and to facilitate access to a larger number of botanical dietary supplements available on the market than previously. Botanical dietary supplements may be formulated for and use only using crude plant samples (e.g., plant parts such as the bark, leaves, or roots) that can be processed by grinding into a dried powder. Plant parts can also be extracted with hot water to form an "herbal tea." Other preparations of botanical dietary supplements include capsules, essential oils, gummies, powders, tablets, and tinctures. Overall, botanical dietary supplements contain bioactive secondary metabolites with diverse chemotypes that typically are found at low concentration levels. These bioactive constituents usually occur in combination with inactive molecules that may induce synergy and potentiation of the effects observed when botanical dietary supplements are taken in their different forms. Most of the botanical dietary supplements available on the U.S. market have been used previously as herbal remedies or as part of traditional medicine systems from around the world. Their prior use in these systems also provides a certain level of assurance in regard to lower toxicity levels. This chapter will focus on the importance and diversity of the chemical features of bioactive secondary metabolites found in botanical dietary supplements that are responsible for their applications. Many of the active principles of botanical dietary substances are phenolics and isoprenoids, but glycosides and some alkaloids are also present. Biological studies on the active constituents of selected botanical dietary supplements will be discussed. Thus, the present chapter should be of interest for both members of the natural products scientific community, who may be performing development studies of the products available, as well as for healthcare professionals who are directly involved in the analysis of botanical interactions and evaluation of the suitability of botanical dietary supplements for human consumption.

Botanical Medicine and Natural Products Used for Erectile Dysfunction

INTRODUCTION

Erectile dysfunction is the persistent or recurrent inability to achieve or maintain an erection sufficient for intercourse. Despite various treatment options, not all patients respond adequately and their usefulness is limited by adverse effects and cost. Botanical medicine and natural products have been and continue to be invaluable and untapped sources of new drugs, including potentially those to treat erectile dysfunction.

OBJECTIVES

To review the current literature on botanical medicine traditionally used as aphrodisiacs and treatment of erectile dysfunction, in particular, scientific and clinical investigations that have been performed, possible active phytoconstituents, and mechanisms of action and to identify gaps in current knowledge to better guide future research efforts.

METHODS

A comprehensive literature search was conducted via PubMed, Scopus, Science Direct, and Web of Science on English publications, using various keywords, for example, "herb", "natural product", combined with "erectile dysfunction", "aphrodisiac", and "sexual performance".

RESULTS

369 relevant articles studying medicinal plants used for erectile dysfunction were analyzed. A total of 718 plants from 145 families and 499 genera were reported to be used traditionally as aphrodisiacs and treatment of erectile dysfunction. Top plants used include Pausinystalia johimbe, Lepidium meyenii, and Panax ginseng. Different plant parts are used, with roots being the most common. Less than half of these plants have been evaluated scientifically, using various research methodologies. Clinical trials conducted were collated. Current scientific investigation shows mixed results about their usefulness in enhancing sexual performance. A limited number of studies have attempted to elucidate the mechanisms of action of these medicinal plants.

CONCLUSION

A comprehensive literature review on botanical medicine and natural products used for treatment of erectile dysfunction was successfully conducted. Although medicinal plants serve as a potential source of lead compounds for erectile dysfunction drugs, further studies are warranted to further evaluate their efficacy and safety. SinVJ-E, Anand GS, Koh H-L. Botanical Medicine and Natural Products Used for Erectile Dysfunction. Sex Med Rev 2020;XX:XXX-XXX.

S, Rao TSS, Koolwal GD. l-arginine and Erectile Dysfunction

l-arginine, being a natural precursor of nitric oxide, is one of the more commonly used adjuvants to regular medicines in the treatment of erectile dysfunction.

Objectives: Here, in this review article, we aim to highlight various studies and the research studies done on l-arginine in the treatment of erectile dysfunction.

Method: Reviewing the databases such as Medline (PubMed), Cochrane Library, Excerpta Medica dataBASE, Trip, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, the Allied and Complementary Medicine Database, and the British Nursing Index.

Results:l-arginine has been studied alone as well as in combination with various other molecules for the treatment of erectile dysfunction, but the studies are very limited in number and have very small sample sizes.

Conclusion: Positive evidence is available for the efficacy of l-arginine and its various combinations. Further research with larger sample sizes and standardized tools are required to recommend the routine use of these products in erectile dysfunction.

Enantioselective Syntheses of (-)-Alloyohimbane and (-)-Yohimbane by an Efficient Enzymatic Desymmetrization Process

Enantioselective syntheses of (-)-alloyohimbane and (-)-yohimbane was accomplished in a convergent manner. The key step involved a modified mild protocol for the enantioselective enzymatic desymmetrization of meso-diacetate. The protocol provided convenient access to an optically active monoacetate in multi-gram scale in high enantiomeric purity. This monoacetate was converted to (-)-alloyohimbane. Reductive amination of the derived aldehyde causes the isomerization leading to the trans-product and allows the synthesis of (-)-yohimbane.

Review: Modern treatment of erectile dysfunction

Within the last two decades, major advances have been made in the development of effective treatments for erectile dysfunction. Oral therapy is now established as the mainstay of treatment and new treatments continue to emerge following the launch of sildenafil in 1998. We review here modern treatment strategies for erectile dysfunction.

Natural aphrodisiacs

INTRODUCTION

The search for a remedy or a prescription that can enhance sexual function and/or treat male erectile dysfunction has been an obsession throughout known history. Whether it was an Eastern civilization or a Western one, religious or atheist, man's aspiration for a better or best "manhood" has been a history-time goal.

AIM

This review will discuss the current research done on the most popular natural aphrodisiacs and examine the weight of evidence to support or discourage the use of any of these substances to enhance sexual desire and/or function.

METHODS

Review of the current evidence on the use of natural substances as aphrodisiacs.

MAIN OUTCOME MEASURES

Efficacy of natural aphrodisiacs in enhancing sexual function in men and women.

RESULTS

There is little evidence from literature to recommend the usage of natural aphrodisiacs for the enhancement of sexual desire and/or performance. Data on yohimbine's efficacy does not support the wide use of the drug, which has only mild effects in the treatment of psychogenic ED. Although there's a positive trend towards recommending ginseng as an effective aphrodisiac, however, more in depth studies involving large number of subjects and its mechanism of action are needed before definite conclusions could be reached. Data on the use of natural aphrodisiacs in women is limited.

CONCLUSIONS

The current body of objective evidence does not support the use of any natural aphrodisiac as an effective treatment for male or female sexual dysfunctions. Potent men and men with ED will continue the search for natural aphrodisiacs despite the current disappointing data on their effectiveness. Care should be taken regarding the fraud addition of sildenafil analogues to natural aphrodisiacs.

Herbal drugs of abuse: an emerging problem

Some herbal products are emerging as popular drugs for recreational abuse. Plant and herbal supplements used recreationally can have a wide spectrum of clinical effects ranging from euphoric and stimulant effects to hallucinogenic experiences. Despite the potential for abuse, addiction, and serious adverse effects, there may be a false perception that these products are all safe, legal, and organic. These perceptions and the ease of accessibility to herbal products could result in greater potential for recreational abuse and subsequent complications presenting to emergency departments. Health care professionals must be cognizant of this emerging problem as increased media coverage and marketing have made these products accessible and recognizable to many young adults and teenagers.

The role of phosphodiesterase inhibitors in impotence

Penile erection is mediated by nitric oxide (NO) and its second messenger cyclic guanosine monophosphate (cGMP). The activity of cGMP is modulated by the enzyme phosphodiesterase (PDE). The most important physiological isoform of the enzyme in the penis is PDE5. Sildenafil is a specific inhibitor of this enzyme which potentiates nitrergic cavernosal relaxation in vitro and in animals. Clinical studies suggest that it is effective in the treatment of male erectile dysfunction (MED), which would make it the first orally active therapy for this condition.

Comparative effects of sildenafil, phentolamine, yohimbine and l-arginine on the rabbit corpus cavernosum

Penile erection involves relaxation of smooth muscle of corpus cavernosum and associated arterioles. Sildenafil, a highly selective inhibitor of phosphodiesterase type 5, is effective in the treatment of erectile dysfunction. The aim of this study is to investigate the effect of sildenafil on smooth muscle of the rabbit corpus cavernosum (RCC) and to compare its effect with those of phentolamine, yohimbine and L-arginine. The effects of sildenafil, phentolamine, yohimbine and L-arginine were studied on the response of the RCC to electrical field stimulation (EFS) as well as on the phenylephrine (PE, 3 x 10(-6) M)-induced tone. EFS caused transient, frequency-dependent relaxation of the RCC that was inhibited by the nitric oxide synthase inhibitor NG-nitro-L-arginine (3 x 10(-5) M). Sildenafil (1 x 10(-9)-1 x 10(-6) M) and phentolamine (1 x 10(-9)-1 x 10(-6) M) enhanced the EFS-induced relaxation in a concentration-dependent manner with ED50 of 0.056 +/- 0.004 and 0.572 +/-0.035 microM at 8 Hz, respectively, yohimbine (3 x 10(-7)-3 x 10(-5) M) and L-arginine (3 x 10(-6)-3 x 10(-4) M) did not show significant effects (ED50 at 8 Hz = 35.84 +/-2.24 and 2.164 +/- 0.174 microM, respectively). Sildenafil (1 x 10(-9) and 1 x 10(-8) M) potentiated the EFS-induced relaxation caused by L-arginine (3 x 10(-5) m). Sildenafil, phentolamine, yohimbine and L-arginine reduced the PE-induced tone to different extents; the ED50 values were 0.81 +/- 0.097, 0.49 +/- 0.025 and 13.97 +/- 1.10 microM, respectively. Maximum concentration of L-arginine used failed to produce 50% relaxation (ED20 = 221.82 +/- 15.71 microM). The muscle relaxant effects of different combinations of sildenafil and L-arginine on PE-induced tone did not differ significantly from the sum of the individual effects. The results demonstrate that sildenafil, when compared to other drugs used in penile erection dysfunction, shows the highest potency on the nitrergic transmission in the RCC. On the other hand, phentolamine was found to possess the highest potency in inducing relaxation of RCC proving that its action is independent on the stimulated neurogenic system. In addition, the combination of less effective doses of sildenafil and L-arginine has a potential advantage on erectile functions. The importance of this combination remains to be solved clinically.

Implications of diabetes mellitus in urology

The incidence of DM is rapidly growing among Americans. DM will rival cancer and heart disease in terms of cost and suffering. The National Institute of Health is tripling the research dollars that are spent on diabetic-related research in an attempt to combat this disease. Urologists are on the front line in the diagnosis and treatment of the complications of DM. The complications of DM that we reviewed in this article, diabetic cystopathy and diabetic ED, can occur in the early stage of DM and often progress in a silent fashion. More awareness and interest are needed to improve our understanding of diabetic complications in urology. Exciting new approaches in the treatment of diabetic cystopathy and ED are being investigated.

Yohimbine treatment of organic erectile dysfunction in a dose-escalation trial

Yohimbine has had questionable effects in men with organic erectile dysfunction. We conducted this study to better define the population of men responsive to yohimbine, because tobacco was thought to affect a regimen of yohimbine more than other risk factors. We measured nocturnal penile tumescence with the RigiScan monitor, hormone profiles, answers to the Florida Sexual Health Questionnaire, and clinical responses at baseline and after two different doses of yohimbine in 18 nonsmoking men with erectile dysfunction. Of the 18 men, nine (50%) were successful in completing intercourse in more than 75% of attempts. The yohimbine responders were men with less severe erectile dysfunction as manifested by improved increased rigidity on RigiScan testing, higher Florida Sexual Health Questionnaire scores, and slightly higher levels of serum testosterone. Yohimbine is an effective therapy to treat organic erectile dysfunction in some men with erectile dysfunction.

Creative-dynamic image synthesis: a useful addition to the treatment options for impotence

In contrast to the impressive advances made in somatic research on erectile dysfunction, psychogenic erectile dysfunction is usually treated as a monolithic block. In this study, we evaluated the erectogenic power of creative-dynamic image synthesis in men with psychogenic erectile dysfunction. Sixty-nine men with a mean age of 46 y, suffering from erectile dysfunction of no known organic cause, were entered in a placebo-controlled study in which the erectogenic power of imagination, yohimbine and a placebo were compared. There was a significant difference between the subjective results of creative-dynamic image synthesis (75% increase of potency) and those achieved through treatment with the drug yohimbine (55% increase in potency) and with a placebo (30% increase in potency). Creative-dynamic image synthesis is a potent initiator of erections in men with psychogenic erectile dysfunction, has no known side effects and is very cost-effective.

Yohimbine: a clinical review

Although yohimbine (YOH) has been available for the treatment of male erectile dysfunction (ED) for longer than Viagra, there is a perception that little is known about the clinical performance of the drug. This review attempts, by comprehensive analysis of the literature, to cover the clinical, pharmacological, and therapeutic profiles of YOH, relevant to its potential utility in the management of patients with ED. Relatively few well-designed studies have been completed. From these, however, it can be concluded that YOH as monotherapy possesses only modest efficacy in ED patients. In acute and chronic (long-term) studies, YOH has been found to be relatively free of side effects over the dose range predicted to be effective in ED. At much higher doses, the most frequently observed effects, consistent with the primary pharmacological action of the drug, are elevation of blood pressure, a slight anxiogenic action, and increased frequency of urination. These side effects are all easily reversible on termination of YOH therapy. There is increasing evidence that the erectogenic action of YOH can be augmented by concomitant administration of agents that augment the release and/or action of nitric oxide in the corpus cavernosum. YOH has yet to be studied in female sexual dysfunction. Overall, the benefit risk profile of YOH would indicate that it has potential, more probably as part of a combination strategy, e.g., with a drug that enhances the nitric oxide pathway, in the treatment of ED.

Alpha 2-adrenoceptor antagonists: effects on ejaculation, penile erection and pelvic thrusting behavior in dogs

We previously reported that systemic administration of yohimbine, an alpha2-adrenoceptor antagonist, exerts a biphasic effect (stimulating and suppressing) on ejaculation in dogs, when this function is analyzed using the amount of ejaculated semen in response to genital stimulation. To clarify the effect of alpha2-adrenoceptor blockade on male sexual function, we investigated the effects of four selective alpha2-adrenoceptor antagonists, rauwolscine, idazoxan, RX821002 and mydaglizole, on sexual responses (ejaculation, penile erection and pelvic thrusting behavior) elicited by manual penile stimulation in dogs. Rauwolscine (intraperitoneal, 30 min before the testing) caused a biphasic effect on ejaculation; the amount of ejaculated semen produced by the stimulation was significantly increased by the lower doses (0.1 and 0.3 mg/kg), whereas it was decreased by the higher doses (1.0 and 2.0 mg/kg). The higher doses of rauwolscine also markedly inhibited both penile erection and pelvic thrusting behavior. Idazoxan and RX821002, at doses of 0.1 and 0.3 mg/kg, caused a significant increase in the amount of ejaculated semen without affecting other sexual functions. RX821002 (2.0 mg/kg), but not idazoxan (2.0 mg/kg), moderately inhibited both penile erection and pelvic thrusting behavior. Mydaglizole, a peripherally acting alpha2-adrenoceptor antagonist, did not affect the sexual responses at any doses (0.1-4.0 mg/kg). In the ejaculatory declining test, all alpha2-adrenoceptor antagonists (0.1 mg/kg), except for mydaglizole, completely prevented the decrease in ejaculatory capacity produced by antecedent ejaculation. These results indicate that, though the range of the effective dose is narrow, the alpha2-adrenoceptor antagonists that can block the central alpha2-adrenoceptors have the stimulatory effects on ejaculatory function. The difference of the sexual effects may be based on the action except for the alpha2-adrenoceptor blockade.

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

The efficacy and safety of sildenafil were evaluated in a randomised, double-blind, placebo-controlled, flexible-dose study in Taiwanese men aged 26 to 80 y with erectile dysfunction (ED) of broad-spectrum aetiology and more than 6 months' duration. A total of 236 patients were randomised at six medical centres in Taiwan to receive either sildenafil (50 mg initially increased if necessary to 100 mg or decreased to 25 mg depending on efficacy and toleration) (n=119) or matching placebo (n=117) taken on an 'as needed' basis 1 h prior to anticipated sexual activity for a period of 12 weeks. At the end of 12 weeks, the primary efficacy variables relating to the achievement and maintenance of erections sufficient for sexual intercourse, and the secondary efficacy variables, which included: (1) the five separate domains of sexual functioning of the IIEF (International Index of Erectile Function) scale, (2) the percentage of successful intercourse attempts; and (3) a global assessment of erections, were all statistically significantly improved by sildenafil in comparison with placebo (P<0.0001). Treatment-related adverse events occurred in 43.7% of patients receiving sildenafil and 18.8% receiving placebo. The most common adverse events with sildenafil were flushing, dizziness and headache (25.2, 6.7 and 5.9% of patients, respectively), and most were mild in nature. The efficacy and safety of sildenafil in the population of Taiwanese men appears similar to that reported in other studies in western populations.

Male sexual function and its disorders: physiology, pathophysiology, clinical investigation, and treatment

This review is designed to help the reproductive endocrinologist integrate his or her professional activity with those of other disciplines including urology, radiology, neurology, and psychology in order to successfully manage all of the inseparable aspects of male sexual and reproductive functioning. Significant advances in the field of male sexual physiology and pathophysiology and new methods of investigation and treatment of male sexual disorders are outlined. The review synthesizes available data on the following: norms of sexual organs, aging and sexuality, role of central and peripheral neurochemicals in each stage of the sexual cycle, role of corporeal smooth muscles in the hemodynamic control of erection and detumescence, influence of psychological factors, drugs, and disease on all aspects of sexual functioning, and use of nocturnal penile tumescence monitoring, imaging investigations, and neurophysiologic studies in the diagnostic workup of males with sexual dysfunction. Clinical algorithms are presented where appropriate. Extensive discussions on newly developed strategies in psychological and behavioral counseling, drug therapy, tissue engineering, nonsurgical devices, and surgical treatments for all forms of sexual disorders are also provided. Lastly, the effect of sexual dysfunction and its treatment on quality of life in affected men is addressed, along with recommendations for future research endeavors.

Phentolamine mesylate relaxes rabbit corpus cavernosum by a nonadrenergic, noncholinergic mechanism

The contribution of NO-cGMP dependent pathway to phentolamine mesylate-evoked nonadrenergic, noncholinergic relaxation of rabbit corpus cavernosum was investigated in vitro. Stimulation of nonadrenergic, noncholinergic neurons of the rabbit corpus cavernosum elicited frequency-related relaxation that was significantly attenuated by L-NAME (NO synthase inhibitor) or ODQ (an inhibitor of guanylate cyclase). Moreover, tetrodotoxin, a sodium channel blocker, abolished the electrical field stimulation-induced relaxation of rabbit corpus cavernosum, suggesting that neuronal release of NO mediates relaxation to electrical field stimulation. Phentolamine mesylate (30 and 100 nM) dose-dependently enhanced electrical field stimulation-induced relaxation of the rabbit corpus cavernosum. Prazosin (30 microM) and yohimbine (30 microM) failed to affect phentolamine mesylate-mediated nonadrenergic, noncholinergic rabbit penile smooth muscle relaxation, suggesting that phentolamine relaxes rabbit corpus cavernosum independent of alpha-adrenergic receptor blockade. In contrast, pretreatment of the rabbit cavernosal strips with L-NAME significantly-attenuated electrical field stimulation produced relaxations to phentolamine mesylate, suggesting that phentolamine mesylate relaxes rabbit corpus cavernosum by activating NO synthase. The data suggest that phentolamine mesylate relaxes nonadrenergic noncholinergic neurons of the rabbit corpus cavernosum by activating NO synthase and is independent of alpha-adrenergic receptor blockade.

Asian sildenafil efficacy and safety study (ASSESS-1): a double-blind, placebo-controlled, flexible-dose study of oral sildenafil in Malaysian, Singaporean, and Filipino men with erectile dysfunction. The Assess-1 Study Group

OBJECTIVES

To evaluate the efficacy, safety, and tolerability of oral sildenafil in Asian men with erectile dysfunction of various causes (organic, psychogenic, or mixed) and of more than 6 months' duration.

METHODS

In this double-blind, parallel-group trial conducted at eight centers in Malaysia, the Philippines, and Singapore, 254 men, 26 to 78 years old, were randomized to 12 weeks of sildenafil or placebo taken as needed 1 hour before anticipated sexual activity. Initially, the sildenafil (n = 127) or matching placebo (n = 127) dose was 50 mg but could be increased to 100 mg or decreased to 25 mg because of a lack of efficacy or intolerance, respectively. Efficacy was assessed by the 15-question International Index of Erectile Function, patients' event logs of sexual activity, and a global efficacy question about erections.

RESULTS

The two primary efficacy variables relating to achievement and maintenance of an erection sufficient for sexual intercourse, as assessed by the mean scores for International Index of Erectile Function question 3 (4.22 versus 2.59) and question 4 (4.15 versus 2.41), were both significantly higher with sildenafil than with placebo (P <0.0001). In addition, the five separate International Index of Erectile Function domains of sexual function, the percentage of successful intercourse attempts, and the global efficacy assessment of erections revealed significantly greater treatment effects in favor of sildenafil (P <0.0001 versus placebo for all variables). Treatment-related adverse events occurred in 22.8% of patients who received sildenafil and in 10.2% of those who received placebo.

CONCLUSIONS

Sildenafil is an effective and well-tolerated treatment for Asian men with erectile dysfunction of broad-spectrum etiology.

Non-surgical management of erectile dysfunction

Erectile dysfunction is a common and distressing medical condition that is now highly amenable to treatment almost irrespective of the cause. Safe, non-surgical treatments with unequivocal efficacy are psychological therapy, intracorporeal injection of vasoactive drugs, transurethral vasodilators and oral sildenafil, all of which have been reported to have a 50-70% overall response rate. Vacuum constriction devices are acceptable for some, usually older patients and oral yohimbine is thought to have marginal efficacy. Local creams to induce or enhance erectile function are currently being investigated. There is no place for androgen supplementation unless the patient is profoundly hypogonadal. Treatment of hyperprolactinaemia is very effective but is a rare cause of erectile dysfunction. As intercourse may entail an unfamiliar level of physical activity, it is sensible to ensure that the patient is able to climb a flight or two of stairs comfortably without provoking undue breathlessness or chest pain and to provide suitable advice about technique before commencing treatment. Once it is clear to the patients that erectile dysfunction can be satisfactorily overcome, the long-term use of treatments to do so tends to wane. Thus, although the prospect of effective treatment for what had been for many a distressing life sentence has the potential to place new demands on the health service, there is no evidence that restrictions on prescribing will prove economically rational.

Pharmacotherapeutic advances in the treatment of erectile dysfunction

An estimated 20 million to 30 million American men have erectile dysfunction (ED). The past 2 decades of research defining erectile physiology and investigating the pathogenesis of ED have led to the recognition of a predominantly vascular basis for organic male sexual dysfunction. These scientific advances have laid the foundation for the advent of pharmacotherapies. The Food and Drug Administration approval of intracavernosal, intraurethral, and oral pharmacotherapeutics for ED has revolutionized non-surgical management of this condition. The primary care physician is faced with the challenges of diagnosis and treatment of ED, as well as referral of patients to urologists. In this article, erectile physiology and pathophysiology are reviewed, and pharmacotherapeutics are classified and discussed by their mechanisms of action and the means of administration. A thorough understanding of these new therapeutic options is key to the accurate diagnosis and successful treatment of ED and maximal patient satisfaction and care.

Combination therapy using oral alpha-blockers and intracavernosal injection in men with erectile dysfunction

OBJECTIVES

Intracavernosal injection with a combination of agents (ie, phentolamine plus papaverine or alprostadil) has been used in an effort to increase efficacy and reduce side effects compared with single agents. The purpose of this pilot study was to determine the potential role of oral alpha-blockers in combination with intracavernosal therapy in men with erectile dysfunction, for whom intracavernosal therapy alone failed.

METHODS

Thirty-eight consecutive men with moderate to severe erectile dysfunction on the basis of history and examination and with minimal or no therapeutic response to intracavernosal alprostadil injection therapy were evaluated. All patients received daily doxazosin titrated to 4 mg over 3 weeks in combination with intracavernosal therapy as needed for 12 weeks. Efficacy was assessed at 4, 8, and 12 weeks after doxazosin titration using the 1 5-item, self-administered International Index of Erectile Function (IIEF) and a global efficacy question (GEQ: Did treatment improve your erections?).

RESULTS

For the group, the mean baseline IIEF score before therapy was 29.7+/-9.8. After intracavernosal therapy (mean dose 34.7+/-7.3 microg), IIEF improved to 36.1+/-1 1.4 (17.7%). After addition of doxazosin, IIEF improved to 48.6+/-13.4, 46.4+/-10.9, and 51.5+/-14.3 at 4, 8, and 12 weeks, respectively (P < 0.01). The GEQ response improved from 25.7% at baseline to 81.4% at 12 weeks. Overall 22 (57.9%) of 38 patients with the combined regimen had a significant (more than 60% improvement in IIEF) therapeutic response.

CONCLUSIONS

The addition of an oral alpha-blocker may have a beneficial effect in patients with erectile dysfunction for whom intracavernosal therapy alone fails. The synergistic effects of vascular dilation and blockade of sympathetic inhibition may explain this response. The potential role of alpha-blockade in synergy with other agents designed to treat erectile dysfunction remains to be determined.

Interaction of the anxiogenic agent, RS-30199, with 5-HT1A receptors: modulation of sexual activity in the male rat

RS-30199 has been shown previously to have atypical interactions at 5-HT1A receptors. RS-30199 and RS-64459, an analogue of buspirone with a buspirone side chain, were compared with the classic, partial agonist at 5-HT1A receptors, 8-hydroxy-2 (di-n-propylamino) tetralin (8-OH-DPAT) and buspirone. At human (h) 5-HT1A receptors in CHO cells, RS-30199-193 (racemate) and its enantiomers (-197, -198) inhibited [3H]-8-OH-DPAT binding (RS-30199-198, ki, 29.7 +/- 11.7 nM; RS-30199-197, ki, 74.1 +/- 11.7 nM) as did RS-64459 (ki, 24.9 +/- 6.0 nM), but RS-30199-197 and -198 were almost full agonists in a [35S]-GTPgammaS binding assay, whereas RS-64459 was a partial agonist, resembling buspirone and 8-OH-DPAT. RS-64459 and the enantiomers of RS-30199 had weaker affinity for 5-HT2C and 5-HT7 receptors. These compounds did not induce the 5-HT behavioural syndrome in male rats. However, in a model where naive male rats were introduced to estrogen-progesterone primed, sexually receptive female rats, RS-30199-197 (0.1, 1, 10 mg/kg, s.c.) had a profound inhibitory effect on sexual behaviour score. Neither buspirone nor 8-OH-DPAT reduced the sexual behaviour score. Unlike 8-OH-DPAT, which shortens intromission latency, RS-30199 prolonged intromission latency. RS-30199 (10 mg/kg s.c.) fully inhibited the facilitation of sexual behaviour caused by the alpha2-adrenoceptor antagonist, delequamine (0.1 mg/kg, p.o.). In contrast, RS-64459 (100, 250, 1000 and 4000 microg/kg, s.c.) failed to modify the sexual behaviour score and did not modify intromission latency. The differences between the effects of RS-30199 and RS-64459 in binding and functional experiments are supported by molecular models of the receptor-ligand interaction, where the compounds interact in different ways with the receptor; a model is proposed for the allosteric interaction of different agents with the receptor, resulting in different functional profiles. RS-30199 can be considered an atypical agonist at 5-HT1A receptors.

La Yohimbina nel deficit dell'erezione: Studio retrospettivo: Yohimbina in erectile deficit: Retrospective study

A brief literature review shows that Yohimbina gave 45-65% satisfactory results when used to treat erectile deficit. The author then makes a retrospective evaluation of 58 patients, comparing them with a control group of 12 patients treated with a placebo (vit. A+E). The effectiveness of Yohimbina, prescribed with magistral prescription, proved to be between 40 and 70%, depending on the patient's age and type of erectile deficit, and was certainly superior to the placebo.

Oral treatment of erectile dysfunction: from herbal remedies to designer drugs

The erect penis has always been a symbol of power, virility, and fertility. Inability to obtain or maintain an erection, known clinically as erectile dysfunction, is a major health problem. It can cause considerable distress, unhappiness, and relationship problems. The search has therefore continued from time immemorial to find an effective safe, and easy to administer treatment for erectile problems. Although a number of these treatments became available in the last two decades, they all had problems with efficacy, safety, or ease of administration. Clinicians in this field often are told at the end of an assessment interview, "I wish you have a magic pill". An effective and safe oral treatment is, no doubt, the most acceptable and easy to use option. Finding such a treatment has always been the dream of many scientists, and many attempts have been made over the years. These ranged from herbal remedies used by native healers, mostly in Eastern countries, to the more sophisticated designer drugs, which are based on a better understanding of the physiological mechanism of erection. This article describes some of these attempts.

Yohimbine for erectile dysfunction: a systematic review and meta-analysis of randomized clinical trials

PURPOSE

Erectile dysfunction is a common problem, particularly in diabetics. It is associated with a considerable burden of suffering. No generally accepted drug treatment exists. We systematically reviewed and meta-analyzed all randomized, placebo controlled trials of yohimbine monotherapy for erectile dysfunction to determine its therapeutic efficacy. Our secondary aim was to evaluate the safety of yohimbine.

MATERIALS AND METHODS

We used computerized literature searches and standardized data extraction to rate methodological quality in a meta-analysis using computer statistical software.

RESULTS

Seven trials fit the predefined inclusion criteria. Overall methodological quality of these studies was satisfactory. The meta-analysis demonstrated that yohimbine is superior to placebo in the treatment of erectile dysfunction (odds ratio 3.85, 95% confidence interval 6.67 to 2.22). Serious adverse reactions were infrequent and reversible.

CONCLUSIONS

The benefit of yohimbine medication for erectile dysfunction seems to outweigh its risks. Therefore, yohimbine is believed to be a reasonable therapeutic option for erectile dysfunction that should be considered as initial pharmacological intervention.