Current and emerging treatment options for premature ejaculation

Premature ejaculation (PE) is a prevalent male sexual dysfunction. Current standard treatment regimens include behavioural therapies, topical anaesthetics, dapoxetine and other selective serotonin reuptake inhibitors (SSRIs). Most of the pharmacotherapeutic options target neurotransmitters (such as serotonin and oxytocin) that have a role in the ejaculation mechanism. However, these treatments are mildly effective and only provide a temporary delay in the ejaculation latency time, and PE recurs when the treatment is stopped. Thus, a treatment for PE is urgently needed and research is ongoing to find the ideal PE therapy. The efficacy and safety of topical anaesthetics and SSRIs in delaying ejaculation have been confirmed in many well-designed controlled trials. Both preclinical and clinical studies on new-generation SSRIs are ongoing. Moreover, promising results came from clinical trials in which the efficacy of on-demand PE therapies targeting neurotransmitters other than serotonin, such as α1-adrenoceptor antagonists and oxytocin antagonists, was assessed. Surgical intervention and neuromodulation have been proposed as potential treatment options for PE; however, current PE guidelines do not recommend these treatments owing to safety concerns.

Ejaculatory and Orgasmic Dysfunction Following Prostate Cancer Therapy: Clinical Management

The majority of sexual health research has focused on erectile dysfunction following prostate cancer treatment. Ejaculatory and orgasmic dysfunction are significant side effects following the treatment of prostate cancer. Orgasmic dysfunction covers a range of issues including premature ejaculation, anorgasmia, dysorgasmia, and climacturia. This review provides an overview of prevalence and management options to deal with orgasmic dysfunction. A Medline Pubmed search was used to identify articles relating to these problems. We found that orgasmic dysfunction has a very large impact on patients’ lives following prostate cancer treatment and there are ways for physicians to treat it. Management of patients’ sexual health should be focused not only on erectile dysfunction, but on orgasmic dysfunction as well in order to ensure a healthy sexual life for patients and their partners.

Antidepressant-induced sexual dysfunction in men

Most of the available antidepressant medications, including tricyclic antidepressants, monoamine oxidase inhibitors, selective serotonin reuptake inhibitors, and dual noradrenergic/serotonergic reuptake inhibitors have been reported to be associated with sexual dysfunction in both sexes. This manuscript reviews evidence concerning the relative incidence of treatment emergent sexual dysfunction in men being treated with antidepressant drugs. Both double-blind controlled trials and large clinical series report a high incidence of sexual dysfunction, especially ejaculatory delay, with serotonergic drugs. The incidence of sexual dysfunction in men appears to be much lower with drugs whose primary mechanism of action involves adrenergic or dopaminergic systems.

Current therapeutic strategies for premature ejaculation and future perspectives

Premature ejaculation (PE) is a common sexual disorder in men that is mediated by disturbances in the peripheral and central nervous systems. Although all pharmaceutical treatments for PE are currently used 'off-label', some novel oral agents and some newer methods of drug administration now provide important relief to PE patients. However, the aetiology of this condition has still not been unified, primarily because of the lack of a standard animal model for basic research and the absence of a widely accepted definition and assessment tool for evidence-based clinical studies in patients with PE. In this review, we focus on the current therapeutic strategies and future treatment perspectives for PE.

Disorders of orgasm and ejaculation in men

INTRODUCTION

Ejaculatory/orgasmic disorders are common male sexual dysfunctions, and include premature ejaculation (PE), inhibited ejaculation, anejaculation, retrograde ejaculation, and anorgasmia.

AIM

To provide recommendations and guidelines concerning current state-of-the-art knowledge for management of ejaculation/orgasmic disorders in men.

METHODS

An international consultation in collaboration with the major urology and sexual medicine associations assembled over 200 multidisciplinary experts from 60 countries into 25 committees. Committee members established specific objectives and scopes for various male and female sexual medicine topics. The recommendations concerning state-of-the-art knowledge of disorders of orgasm and ejaculation represent the opinion of seven experts from seven countries developed in a process over a 2-year period.

MAIN OUTCOME MEASURE

Expert opinion was based on grading of evidence-based medical literature, widespread internal committee discussion, public presentation and debate.

RESULTS

Premature ejaculation management is largely dependent upon etiology. Lifelong PE is best managed with PE pharmacotherapy (selective serotonin re-uptake inhibitor [SSRI] and/or topical anesthetics). The management of acquired PE is etiology specific and may include erectile dysfunction (ED) pharmacotherapy in men with comorbid ED. Behavioral therapy is indicated when psychogenic or relationship factors are present and is often best combined with PE pharmacotherapy in an integrated treatment program. Retrograde ejaculation is managed by education, patient reassurance, pharmacotherapy, or bladder neck reconstruction. Delayed ejaculation, anejaculation, and/or anorgasmia may have a biogenic and/or psychogenic atiology. Men with age-related penile hypoanesthesia should be educated, reassured, and instructed in revised sexual techniques which maximize arousal.

CONCLUSIONS

Additional research is required to further the understanding of the disorders of ejaculation and orgasm.

Premature ejaculation: current medical treatment and new directions (CME)

INTRODUCTION

Premature ejaculation (PE) is the most common form of male sexual dysfunction. Until very recently, scientific investigation of PE has been hampered by a lack of standardized definitions and objective, validated questionnaires. Small numbers of randomized controlled studies evaluating various treatment options have also added to the challenges facing the clinicians who manage PE.

AIM

This article provides a summary of some of the more relevant the peer-reviewed literature pertaining to the medical therapy of premature ejaculation.

METHODS

A retrospective review of peer reviewed publications relevant to the field of premature ejaculation and related medical therapies.

MAIN OUTCOME MEASURES

Review of safety and efficacy of various medical therapies for premature ejaculation.

RESULTS

Selective serotonin release inhibitors have been the most promising agents to date. The on-demand "PRN" use of these agents is more convenient, but its efficacy is less well established. Chronic use of this class of medications has been associated with minor, but bothersome side effects. More recently, concern over the risk of an increased suicide rate in young men upon initiation of SSRIs has dampened enthusiasm. Recent experience with the use of Tramadol raises the hope that this might prove to be an agent as effective as SSRIs with less worrisome risk of side-effects. New trials on novel formulations of topical solutions are currently underway in the United States.

CONCLUSIONS

Interest in medical therapy for PE is rapidly increasing and reflected in a disproportionate number of publications in this field in the past few years. Clinical research in this field is hampered by the complexity, variability among different men and cultures, and subjectivity of PE. Reliable, appropriately controlled and assessed studies are generally lacking and carefully devised, methodically conducted research is much needed.

An evidence-based definition of lifelong premature ejaculation: report of the International Society for Sexual Medicine Ad Hoc Committee for the Definition of Premature Ejaculation

OBJECTIVE

To develop a contemporary, evidence-based definition of premature ejaculation (PE).

METHODS

There are several definitions of PE; the most commonly quoted, the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders - 4th Edition - Text Revision, and other definitions of PE, are all authority-based rather than evidence-based, and have no support from controlled clinical and/or epidemiological studies. Thus in August 2007, the International Society for Sexual Medicine (ISSM) appointed several international experts in PE to an Ad Hoc Committee for the Definition of PE. The committee met in Amsterdam in October 2007 to evaluate the strengths and weaknesses of current definitions of PE, to critically assess the evidence in support of the constructs of ejaculatory latency, ejaculatory control, sexual satisfaction and personal/interpersonal distress, and to propose a new evidence-based definition of PE.

RESULTS

The Committee unanimously agreed that the constructs which are necessary to define PE are rapidity of ejaculation, perceived self-efficacy, and control and negative personal consequences from PE. The Committee proposed that lifelong PE be defined as a male sexual dysfunction characterized by ejaculation which always or nearly always occurs before or within about one minute of vaginal penetration, and the inability to delay ejaculation on all or nearly all vaginal penetrations, and negative personal consequences, such as distress, bother, frustration and/or the avoidance of sexual intimacy. This definition is limited to men with lifelong PE who engage in vaginal intercourse. The panel concluded that there are insufficient published objective data to propose an evidence-based definition of acquired PE.

CONCLUSION

The ISSM definition of lifelong PE represents the first evidence-based definition of PE. This definition will hopefully lead to the development of new tools and patient-reported outcome measures for diagnosing and assessing the efficacy of treatment interventions, and encourage ongoing research into the true prevalence of this disorder, and the efficacy of new pharmacological and psychological treatments.

Premature ejaculation: current and future treatments

Premature ejaculation (PE) is recognized to be the most common male sexual disorder. PE provides difficulties for professionals who treat this condition because there is neither a universally accepted definition nor a medication approved by the Food and Drug Administration (FDA). Despite these shortcomings, physicians continue to diagnose their patients with PE according to major guidelines and treat them with either behavioral therapies or off-label medications. This review focuses on current and emerging treatment options and medications for PE. Advantages and limitations of each treatment option are discussed in the light of current published peer-reviewed literature.

Premature ejaculation: state of the art

Premature ejaculation (PE) is a frequent male sexual complaint.This occurrence does not automatically imply the existence of a male sexual disorder. The current DSM definition of PE has a low positive predictive value with a high associated risk for false-positive diagnoses of PE. A new classification in four well-defined PE syndromes has recently been proposed for the pending DSM-V. According to this new classification there are different pathophysiologies and treatments of PE, dependent on the underlying PE syndrome. Some types are particularly neurobiologically or medically determined and need drug treatment; other types, which are mainly psychologically determined, need psychotherapy or both drug treatment and psychotherapy. A meta-analysis of all selective serotonin reuptake inhibitors (SSRIs) and clomipramine studies, which were performed according to current standards of evidence-based medicine, demonstrated a similar efficacy for the daily treatment with the serotonergic antidepressants paroxetine hemihydrate, clomipramine, sertraline, and fluoxetine, with paroxetine hemihydrate exerting the strongest effect on ejaculation. On-demand treatment with SSRIs generally exerts much less ejaculation delay than daily SSRI treatment. Other on-demand treatment options are the topical use of anesthetics, tramadol, and phosphodiesterase type 5 inhibitors. Caution is needed with tramadol with regard to its potential addictive properties. There is insufficient evidence for the ejaculation delaying effects of phosphodiesterase type 5 inhibitors and intracavernous injection of vasoactive drugs.

Tramadol HCL has promise in on-demand use to treat premature ejaculation

INTRODUCTION

Premature ejaculation (PE) is a worldwide problem without an approved treatment. Selective serotonin reuptake inhibitors (SSRIs) are widely used "off label" as pharmacotherapeutic agents in the treatment of PE.

AIM

This study investigates Tramadol efficacy for on-demand treatment of PE.

MAIN OUTCOMES MEASURES

Intravaginal ejaculation latency time (IELT) was used as an objective tool to assess the efficacy of the investigated treatments.

MATERIALS AND METHODS

Single-blind, placebo-controlled, crossover, stopwatch monitored two-period study was conducted, on 60 patients with lifelong PE. PE was defined as IELT of <2 minutes in 80% of intercourse episodes. A total of 25 mg of Tramadol hydrochloride was given to one group (30) prior to intercourse and placebo was supplied for the other group (30) for 8 weeks. Drugs were taken 1-2 hours before sexual activity and sexual intercourse was required at least once per week. After the initial treatment period, the two groups took the alternate medication for another 2 months. The two 8-week treatment periods were separated by 1 week washout period. IELT was timed by a stopwatch at each intercourse and was reported by patients or partners.

RESULTS

The baseline (mean +/- SD) IELT for patients before treatment was 1.17 +/- 0.39 minutes. At the end of the treatment period utilizing the active drug, the mean IELT was increased significantly in patients on Tramadol treatment to 7.37 +/- 2.53 minutes. The same patients on placebo medication had mean IELT of only 2.01 +/- 0.71 minutes. Patients uniformly reported satisfaction with their resulting control over ejaculation.

CONCLUSIONS

Tramadol, a drug with a proven safety record as an anti-inflammatory agent, shows promise as a drug for treating rapid ejaculation.

Premature Ejaculation

Premature ejaculation (PE) is a frequent male sexual complaint that is mediated mainly by disturbances of serotonergic neurotransmission and certain serotonin (5-HT) receptors and, to a lesser extent, oxytocinergic neurotransmission in the CNS. The current Diagnostic Manual of Mental Disorders (fourth edition, revised text) [DSM-IV-TR] definition of PE has a low positive predictive value and is inadequate for clinical, epidemiological and drug treatment research. Categorisation of PE into four well defined syndromes has recently been proposed for the pending DSM (fifth edition) definition of PE. Over the last decade, an increasing number of studies of drug treatment of PE have been published. A meta-analysis of those studies, conducted in accordance with current standards of evidence-based medicine, demonstrated similar efficacies for daily treatment with the serotonergic antidepressants paroxetine hemihydrate, clomipramine, sertraline and fluoxetine, with paroxetine (hydrochloride) hemihydrate exerting the strongest effect on ejaculation. On the basis of fundamental insights into serotonergic neurotransmission, it has been suggested that on-demand selective serotonin reuptake inhibitor (SSRI) treatment will not lead to similarly impressive delays in ejaculation as has been observed with daily SSRI treatment. Indeed, some on-demand studies with SSRIs and studies with the new SSRI dapoxetine have shown a weak ejaculation-delaying effect after 1-2 hours of drug intake. Apart from daily treatment with SSRIs, PE can be delayed by on-demand use of topical anaesthetics and tramadol. Treatment with phosphodiesterase type 5 inhibitors should not be prescribed to men with PE with normal erectile function, but may be used if PE is accompanied by erectile difficulties. There is no scientific support for treatment of PE with intracavernous injection of vasoactive drugs. Animal studies have shown that strong immediate ejaculation delay may be induced by administration of a combination of an SSRI with a serotonin 5-HT(1A) receptor antagonist. The combination of an SSRI and any other compound that immediately and potently raises serotonin neurotransmission and/or use of oxytocin receptor antagonists may form the basis for the development of new on-demand and/or daily drugs for the treatment of PE.

Effects of a new functional-sexological treatment for premature ejaculation

Premature ejaculation is the most-prevalent sexual problem in men. Various treatments have been developed to increase control over the moment of ejaculation, with two of the most frequent techniques used in behavior therapy being the squeeze method developed by Masters and Johnson (1970) and the "stop-and-start" technique described by Semans (1956). These treatments are effective and improve matters in most cases. However, couples can be averse to using them, with some women reluctant to squeeze their partner's penis and some couples unwilling to interrupt sexual interaction once initiated. Under a new functional-sexological treatment intended to improve control over the moment of ejaculation, men learn how to control their arousal without having to interrupt sexual activity. In this study, we compared three groups of couples in which the man suffered from premature ejaculation. One followed the new functional-sexological treatment, another followed a behavioral treatment--including the squeeze and stop-and-start techniques--and a control group was placed on a waiting list. We used several questionnaires to assess the effects of the various treatments. Moreover, subjects provided an objective measure of duration of intercourse from penetration to ejaculation. These measures were taken pre- and posttreatment and at three-month follow-up. We ran analyses of variance to assess the effects of the treatments. Results indicate that the new treatment is very effective. We observed significant improvements in duration of intercourse, sexual satisfaction, and sexual functioning. The subjects in the behavioral treatment group obtained similar results. Furthermore, subjects from both groups were satisfied with their respective treatment.

Emerging drugs for premature ejaculation

Lifelong premature ejaculation (PE) is a frequent male sexual dysfunction and is thought to be mediated in part by disturbances of serotonergic (5-hydroxytryptamine; 5-HT) neurotransmission and ejaculation-mediating 5-HT receptors in the CNS. The aetiology of the dysfunction is unclear, but probably includes neurobiological and environmental factors. Lifelong PE is a syndrome characterised by a cluster of symptoms. Rapid ejaculations become manifest around the first sexual encounters in puberty or adolescence. Intravaginal ejaculation latency time usually occurs within 30-60 s, or maximally within 2 min after vaginal penetration, is present with nearly every sexual partner, and remains similar throughout life or may aggravate during ageing. The syndrome may lead to secondary psychological, sexual and relationship problems. Daily treatment with some selective serotonin re-uptake inhibitors (SSRIs) leads to strong ejaculation delay, but may be accompanied by side effects. New treatment with SSRIs with a short half-life (if approved) for on-demand use 1-2 h prior to coitus exerts less ejaculation-delaying effects than daily SSRI strategies. Animal studies have shown that strong, immediate ejaculation delay may be induced by the combination of an SSRI with a 5-HT(1A) receptor antagonist. The combination of an SSRI and any other compound that immediately strongly raises 5-HT neurotransmission may form the basis for the development of new on-demand drugs to treat PE.

Lifelong premature ejaculation: definition, serotonergic neurotransmission and drug treatment

The ejaculation distribution theory (EDT) postulates a biological continuum of the intravaginal ejaculation latency time (IELT) in men. Such an continuum has recently been found in two epidemiological stopwatch studies. In addition, a continuum of ejaculation latency time has also been demonstrated in laboratory rats. It is suggested that the invariable parts of ejaculation, i.e. premature and retarded ejaculation are highly influenced by genetic and neurobiological factors. In contrast, superimposed on biological roots, ejaculation of men, in the middle part of the continuum, is probably more easily influenced by environmental and psychological factors. A meta-analysis of 35 daily SSRI and clomipramine treatment studies demonstrated a similar efficacy for paroxetine, clomipramine, sertraline and fluoxetine, with paroxetine exerting the strongest effect on ejaculation. Based on fundamental insights into serotonergic neurotransmission, it is suggested that on-demand conventional SSRI treatment will not lead to similarly impressive ejaculation delay as that found after daily conventional SSRI treatment. Future studies with SSRIs with short half-lives, short T(max) and high C(max )should elucidate whether these pharmacokinetic properties are able to affect the pharmacodynamics of 5-HT neurons in such a way that immediate clinically relevant ejaculation delay occurs.

On-Demand Treatment of Premature Ejaculation with Clomipramine and Paroxetine: A Randomized, Double-Blind Fixed-Dose Study with Stopwatch Assessment

OBJECTIVE

To investigate the degree of ejaculation delay induced by on-demand treatment with 20 mg paroxetine and 25 mg clomipramine and to assess the type and severity of non-sexual side-effects of treatment at the day of and the day after treatment with these drugs.

METHOD

A randomized, double-blind, fixed-dose, on-demand study in 30 men with lifelong premature ejaculation was performed. During a 1-month baseline period and a 4-week drug treatment period patients assessed the intravaginal ejaculation latency time (IELT) at home with a stopwatch. Only men with an IELT <1 min were randomly assigned to drug treatment. Patients assessed the drug coitus interval time (DCIT) and used the UKU side effect scale questionnaire at baseline, the day of and the day after intercourse.

RESULTS

On-demand treatment with 25 mg clomipramine, with a mean DCIT of 5.14 h, led to a 4.05 (95%CI: 3.26-5.02) fold-increase of the IELT. On-demand treatment with 20 mg paroxetine, with a mean DCIT of 5.39 h, led to a 1.41 (95%CI: 1.22-1.63) fold-increase of the IELT. Both drugs had a high incidence of non-sexual side effects at the coitus day and the next day. At the day of coitus paroxetine led to significant sleepiness and yawning compared to clomipramine. At the day after coitus clomipramine induced significant nausea compared to paroxetine.

CONCLUSION

On-demand treatment with 25 mg clomipramine led to a clinical relevant ejaculation delay. In contrast, 20 mg paroxetine had no clinical relevant ejaculation delay in men with lifelong premature ejaculation with an IELT of less than 1 minute. Both drugs exert mostly mild yet annoying non-sexual side effects both at the coitus day and the next day.

Relevance of methodological design for the interpretation of efficacy of drug treatment of premature ejaculation: a systematic review and meta-analysis

The aim of this systematic review and meta-analysis is to evaluate whether the design and methodology of drug-treatment studies of premature ejaculation affect the efficacy outcome differently. Therefore, methodological, design and efficacy data from 79 studies (3034 males), published between 1943 and 2003, are reviewed. A meta-analysis is performed on 43 selective serotonin reuptake inhibitors (SSRIs) and clomipramine studies (1514 males), published between 1973 and 2003; these studies were pooled to provide a summary variance-weighted effect size. The antidepressant-induced percentage increase of the intravaginal ejaculation latency time (IELT) was calculated and examined against various methodological items. A significant difference in efficacy between SSRIs was observed. Using daily treatment, paroxetine appeared more effective than the other SSRIs. Retrospective use of a questionnaire, subjective reports, single-blind and open study designs generate far greater variability of ejaculation time both at baseline and during active drug treatment than real time assessment by stopwatch. In conclusion, at daily treatment, the overall efficacy of paroxetine, clomipramine, sertraline and fluoxetine is comparable, but paroxetine exerts the strongest ejaculation delay. Only eight (18.5%) studies on antidepressant treatment fulfilled all criteria used in evidence-based medicine, for example, randomised, double-blind studies with prospective real time (stopwatch) assessment of the IELT at each intercourse. Single-blind studies, open designs, retrospective reporting, or the use of a questionnaire to assess ejaculation time should be avoided.

Lifelong premature ejaculation: from authority-based to evidence-based medicine

Historically, four periods can be distinguished in the approach to and treatment of lifelong premature ejaculation. Although drug treatment has been an option for many decades, psychotherapy prevailed as the first choice of treatment. However, the application of the principles of evidence-based medicine shows that there is little evidence to support the psychological approach and behavioural treatment. In contrast, controlled trials with selective serotonin reuptake inhibitors, clomipramine and anaesthetic ointments have repeatedly shown the efficacy of both daily and 'as-needed' drug treatment to delay ejaculation. Currently, an evidence-based approach is gradually replacing the authority-based psychological attitude that characterized the view of premature ejaculation. Based on psychopharmacological studies there is evidence that premature ejaculation is related to a diminished serotonergic neurotransmission, and 5-HT2C or 5-HT1A receptor disturbances. Moreover, animal studies show the presence of a distinct ejaculation-related neural circuit in the central nervous system; its role in premature ejaculation remains to be elucidated.

Towards evidence-based drug treatment research on premature ejaculation: a critical evaluation of methodology

In the last decade, an increasing number of drug studies on premature ejaculation have been published. The methodology used in these studies differed widely. In this review, it is therefore questioned as to how far the differences in methodology could have influenced clinical outcomes. The aim of the present review was to compare the different methodologies that were used in drug studies on premature ejaculation. The majority of these studies were conducted between 1973 and 2003 and were strikingly different in study design and in the quantification of clinical outcomes. It appeared that in some of these studies, placebo and active drug effects were neglected due to an erroneous methodology. The few studies that were using stopwatch assessment at each intercourse at baseline and during treatment and in which the intravaginal ejaculation latency time (IELT) was included appeared to be comparable in their results. The use of a well-defined definition of premature ejaculation, for example, an IELT of less than 1 min revealed reproducible results. Finally, the retrospective use of a questionnaire or a subjective report on ejaculation time induced higher effects with regard to placebo effects and an underestimation of active drug effects. In conclusion, for drug treatment research of premature ejaculation it is recommended to use a randomized double-blind prospective design, the use of the IELT, the use of a stopwatch at each coitus both during a baseline period and during drug treatment and a definition of premature ejaculation as an ejaculation that occurs within 1 min after vaginal penetration.

The neurobiological approach to premature ejaculation

PURPOSE

Data showing the neurobiological background of rapid ejaculation was reviewed. In addition, new hypotheses to integrate clinical symptomatology, psychopharmacotherapy and psychotherapy of rapid ejaculation with brain function are provided.

MATERIALS AND METHODS

A computerized MEDLINE search, and manual bibliographic review of cross-references and neurobiological animal studies were performed. These reports were analyzed, summarized and compared with the studies performed by the author.

RESULTS

The literature on premature ejaculation published between 1887 and 2001 was reviewed. It appeared that the various psychological hypotheses and psychotherapies have not adequately been investigated. In contrast, psychopharmacological treatment studies, animal research data and stopwatch assessments in men with rapid (premature) ejaculation indicate that lifelong rapid ejaculation is a neurobiological phenomenon related to central serotonergic neurotransmission and likely influenced by hereditary factors.

CONCLUSIONS

Basic and clinical psychopharmacological studies suggest that premature ejaculation is a not a psychological disturbance but a neurobiological phenomenon.

A comparison of the effects of different serotonin reuptake blockers on sexual behaviour of the male rat

In human males, SSRIs differentially affect (premature) ejaculation; paroxetine and fluoxetine markedly and sertraline, moderately inhibited ejaculation latency, whereas fluvoxamine did not inhibit this parameter (Waldinger, M.D., Hengeveld, M.W., Zwinderman, A.H., Olivier, B., The effect of SSRI antidepressants on ejaculation: a double-blind, randomised, placebo-controlled study with fluoxetine, fluvoxamine, paroxetine and sertraline. J. Clin. Psychopharmacol. (in press)). The present studies tried to investigate, using sexual behaviour in male rats, whether such differences could also be found in animal paradigms of sexual behaviour. In a series of three experiments we compared various specific serotonin reuptake inhibitors (SSRIs) for their ability to suppress sexual behaviour in male rats. In the first experiment sexually experienced rats were tested 60 min after oral administration of clomipramine, fluvoxamine, fluoxetine (all in a range of 0, 3, 10 and 30 mg/kg p.o.), sertraline or paroxetine (both in a range of 0, 1, 3 and 10 mg/kg p.o.). Clomipramine, paroxetine and fluvoxamine did not significantly inhibit male sexual behaviour, although some trends were observed. Sertraline inhibited sexual behaviour at 3 and 10 mg/kg p.o., the effects being stronger at 3 mg/kg p.o. Fluoxetine (3 mg/kg p.o.) facilitated sexual behaviour, while at 30 mg/kg p.o. a modest increase in the postejaculatory interval was noted. In the second experiment, sexual behaviour of sexually naive male rats was slightly inhibited by paroxetine 10 mg/kg p.o., but sertraline (range 1-10 mg/kg p.o.), fluvoxamine and fluoxetine (both in a range of 3-30 mg/kg p.o.) were ineffective. In the last experiment the effects of paroxetine (0-10 mg/kg p.o.), fluvoxamine and fluoxetine (both 0-30 mg/kg p.o.) were studied during an exhaustion design in sexually experienced male rats. As rats get more 'sluggish' when they have had multiple ejaculations, we hoped to see stronger inhibitory effects in the last cycle prior to exhaustion. None of the drugs dose-dependently inhibited the pattern of sexual behaviour during the first sexual cycle. In the last cycle the patterning of sexual behaviour differed, but only paroxetine (10 mg/kg p.o.) inhibited sexual behaviour significantly. The total number' of ejaculations during the test was not reduced by any of the SSRIs tested. Contrary to human findings, we did not find major inhibitory effects of SSRIs on male rat sexual behaviour at non-sedative doses. The only differentiation that could be made is that paroxetine and sertraline had slightly stronger effects than the other 5-HT reuptake inhibitors. Masculine sexual behaviour in rats does not constitute a suitable model to investigate the differential mechanism of sexual inhibition of SSRIs that have been described in human males.

Fluoxetine and premature ejaculation: a double-blind, crossover, placebo-controlled study

The purpose of this study was to investigate the effect of fluoxetine on sexual function in men with premature ejaculation and/or erectile dysfunction and control subjects in a prospective, double-blind, placebo-controlled, crossover study. There were four groups: (1) premature ejaculation (PE, N = 9); (2) premature ejaculation and erectile dysfunction (PE/ED, N = 9); (3) erectile dysfunction (ED, N = 7); and (4) healthy, sexually functional control subjects (N = 15). The study consisted of three 4-week periods: fluoxetine, washout, and placebo (or vice versa). Fluoxetine began at 5 mg/day for 2 weeks, followed by 10 mg/day for 2 weeks. At weeks 0, 4, 8, and 12, subjects visited the laboratory for evaluation of sexual function and assessment of erectile response, ejaculation, and sexual arousal to visual erotic stimulation without and with concomitant vibrotactile stimulation to the penis. At home, daily logs for sexual activities and feelings of well-being were maintained, and nocturnal penile tumescence was measured. The latency to ejaculation increased significantly in the PE/ED group (p = 0.03) and in the PE and the PE/ED group taken together (p = 0.007) but not in the PE group alone. Fluoxetine stimulated objectively but not subjectively measured erectile response during laboratory assessment in all groups. No major side effects were reported. In conclusion, fluoxetine (5-10 mg/day) was effective in increasing latency to ejaculation in patients with PE (PE and PE/ED groups combined).

An open clinical trial of fluoxetine in the treatment of premature ejaculation

There have been an increased number of recent reports on orgasm-related sexual dysfunction coincident with selective serotonin reuptake inhibitor (SSRI) treatment. In contrast, it has also been reported that SSRIs improve sexual dysfunction. Low doses of clomipramine and paroxetine, potent 5-hydroxytryptamine reuptake blockers, have been found to retard ejaculation time. We hypothesized that the SSRI fluoxetine might be effective in treating premature ejaculation. In an 8-week open-label clinical study, 11 male patients with premature ejaculation were treated with fluoxetine. After a washout period of 2 weeks, each patient was assigned to receive fluoxetine, 20 mg/day for 2 weeks, and then titrated to 60 mg/day, depending on the patient's tolerability and clinical response. A within-subjects comparison of pre- and posttreatment intravaginal ejaculation latency time revealed a significant improvement. Fluoxetine treatment produced significant improvements in self-visual analogue scale scores for sexual desire, anxiety for rapid ejaculation, and partner's satisfaction with ejaculation and overall sexual function. These data suggest that serotonergic antidepressants may be effective in treating rapid ejaculation in men and underline the need to carry out a double-blind, placebo-controlled trial to confirm these results.

Antidepressants in the treatment of premature ejaculation

The SSRI antidepressants have emerged as effective new treatment for patients with premature ejaculation whether or not these patients suffer from depression. Clomipramine, fluoxetine, paroxetine, and sertraline seem to be a safe treatment option for patients with premature ejaculation, especially in cases of failed psychological treatment, in rejection of psychological treatment, and when partners are unwilling to cooperate in treatment. Further controlled and larger studies that focus on clinically relevant issues such as dose, length of treatment, maintenance of beneficial effects after treatment discontinuation, and the combination of pharmaco- and behavior therapy for premature ejaculation are warranted. Other medications, such as benzodiazepines, may be useful in some cases of premature ejaculation.

Psychoactive drugs and human sexual behavior: the role of serotonergic activity

A wide range of both prescription and nonprescription drugs has been reported to affect human sexual functioning. While the sexual side effects resulting from drug use have often been attributed to adrenergic, anticholinergic or dopaminergic activity, the present review considers the potential role of serotonin. Based on animal studies, serotonin has been shown to either facilitate or inhibit sexual activity depending on which serotonin receptor subtype is activated. However, few studies have been done in the human that assess the effects of drugs that bind selectively to serotonin receptors. Consequently, little is known about the role of serotonin in human sexual functioning. In this review, a wide range of drugs that affect both brain serotonergic systems and human sexual behavior is examined in an effort to determine the possible role of serotonin in human sexual behavior. A review of the literature is consistent with the hypothesis that the 5-HT1A and the 5-HT2 receptor subtypes play a facilitatory role in human sexual behavior. The evidence suggests that drugs that act as agonists on these receptor sites enhance sexual functioning in the human, while those that act as antagonists inhibit sexual functioning.

Clomipramine: a tricyclic antidepressant effective in obsessive compulsive disorder

Clomipramine hydrochloride, a chlorinated analog of imipramine, is a widely used antidepressant recently approved for use in the U.S. for the treatment of obsessive-compulsive disorder (OCD), a potentially incapacitating affliction. Its primary pharmacologic action is blockade of the reuptake of the neurotransmitter serotonin. Its metabolite, desmethylclomipramine, is a potent norepinephrine reuptake inhibitor. Significant first-pass metabolism reduces oral bioavailability to less than 62 percent. The drug is widely distributed throughout the body (volume of distribution 9-25 L/kg) and is 90-98 percent protein-bound. Clomipramine follows first-order elimination pharmacokinetics, with a plasma half-life of 20-24 hours. Recent double-blind controlled clinical trials have demonstrated the drug's effectiveness in the treatment of OCD. Response is most often associated with doses greater than 75 mg/d, with 250 mg the maximum recommended daily dose. Relapse upon withdrawal is frequently reported. The adverse effect profile of clomipramine is similar to other tricyclic antidepressants, with anticholinergic, cardiovascular, sexual, and central nervous system effects the most prominent.

Anorgasmia from clomipramine in obsessive-compulsive disorder. A controlled trial

Forty-six patients with obsessive-compulsive disorder undergoing a double-blind controlled study of clomipramine and placebo were interviewed to assess changes in sexual function. Of 33 patients with previously normal organism, nearly all of the 24 on clomipramine developed total or partial anorgasmia; none of the 9 on placebo did so. Anorgasmia persisted with minimal tolerance over the five months that clomipramine was taken. Men and women were equally affected. Sexual side-effects are easily missed without a structured interview, and can detract from the value of drug treatment.

Secondary premature ejaculation

Secondary premature ejaculation is a definite entity which can be due to a variety of causes--physical, pharmacological and psychological. The sparse literature on this subject is reviewed and a series of 25 cases of diverse and sometimes unusual aetiology reported. The fact that ejaculatory control can be adversely affected by a variety of physical and psychological conditions has implications for theories as to the cause of the much commoner entity of primary premature ejaculation, for which there is still no generally agreed-upon aetiological formulation.

A double-blind trial of clomipramine in premature ejaculation

A double-blind clinical trial was designed to study the effect of clomipramine in 50 patients complaining of rapid ejaculation. Patients were divided into two groups and each group received 2 periods of 6 consecutive weeks' treatment with drug and placebo, so that comparison can be made between drug and placebo within each group and between the two groups. Analysis of collected data showed a significantly higher percentage of satisfactory performances with the drug than with placebo and maintenance of the beneficial effect after the drug was replaced by placebo.

Further evidence for an inhibitory role of central 5-HT in male rat sexual behavior

The 5-hydroxytryptamine (5-HT) reuptake inhibitors zimelidine (10 mg/kg IP 1.5h pretest) or alaproclate (20 mg/kg IP 1.5h pretest) produced a prolongation of the ejaculation latency and of the post-ejaculatory interval in male rats treated with a subthreshold dose of 5-hydroxytryptophan (5-htp) (12.5 mg/kg IP 1h pretest). The 5-HTP-induced (50 mg/kg IP 1h pretest) prolongation of ejaculatory latency was effectively counteracted by administration of the 5-HT receptor blocking agent metergoline (1 mg/kg IP 1.5h pretest). All animals were treated with an inhibitor of peripheral aromatic amino acid decarboxylase, indicating that the effects are of central origin. The results support the contention that central 5-HT plays an inhibitory role in male rat sexual behavior.

Prolongation of the ejaculation latency in the male rat by thioridazine and chlorimipramine

Thioridazine (3 mg/kg) and chlorimipramine (1.5-6.0 mg/kg) prolonged the ejaculation latency and increased the number of mounts but did not change the number of intromissions preceding ejaculation. Blockade of peripheral and central noradrenaline receptors by phentolamine and phenoxybenzamine respectively resulted in a suppression of all aspects of the sexual behavior with increasing doses. DL-5-HTP (25-100 mg/kg) in combination with an inhibitory of peripheral 5-HTP decarboxylase (benserazide, 25 mg/kg) produced, like chlorimipramine and thioridazine, a prolongation of ejactulation latency and an increase in the number of mounts preceding ejaculation. Selective inhibition of 5-HT reuptake however, by zimelidine (0-20 mg/kg) or alaproclate (0-20 mg/kg) did not affect the mating behavior. At higher doses of these drugs some animals failed to initiate sexual activities. There was an increase in the postejaculatory interval but not change in the ejaculatory latency. It is concluded tha the prolonged ejaculation latencies observed following treatment with thioridazine or chlorimipramine is not due to a blockade of central or peripheral adrenergic alpha-receptors.

Monoamines and sexual behaviour in non-human primates

The experiments described were concerned with elucidating the involvement of monoamines in the sexual behaviour of rhesus monkeys. The measurement of perturbations in the levels and turnover of the acid metabolites of serotonin and dopamine in cisternal cerebrospinal fluid, occurring in response to hormonal manipulations which alter proceptivity and receptivity, has not clarified the ways in which hormones and amines interact. However, the use of psychoactive drugs which alter the activity of monamine neurons in the brain has demonstrated that sexual activity can be profoundly influenced by such procedures. Thus, depletion of serotonin (5-hydroxytryptamine) in the brain using p-chlorophenylalanine reversed the decrease in proceptivity that followed adrenalectomy. Conversely, inhibition of serotonin uptake using chlorimipramine reduced proceptivity and receptivity to very low levels. Both findings point to the apparently important role of serotoninergic neurons in the control of sexual behaviour. Low doses of the dopamine agonist alpha-bromocriptine enhanced the proceptivity of female rhesus monkeys but high doses had no such effect. This behavioural change was not related to the concomitant suppression of serum prolactin and may have been related to presynaptic actions of the drug in a manner postulated to explain similar behavioural effects in rats. The beta-blocker oxprenolol had the interesting property of improving the sexual performance of male rhesus monkeys, a behavioural effect consistent with an anxiolytic action, although endocrine (prolactin, cortisol) measures did not provide support for such a view. Defining the nature of the interaction between hormones and monoamine-containing neurons in the brain in behavioural contexts is shown to depend largely on the application of precise neuroanatomical and neuropharmacological techniques. However, the use of systemic treatment with psychoactive drugs used widely in clinical practice, in carefully controlled, behavioural and and endocrine experiments, is likely to provide invaluable information on where and how to investigate the neural mechanisms involved.