Supraspinal site of action for the inhibition of ejaculatory reflex by dapoxetine

OBJECTIVES: The aim of the study was to determine whether dapoxetine, a short-acting selective serotonin reuptake inhibitor, acts at the spinal or supraspinal level to inhibit the ejaculatory reflex. METHODS: The pudendal motoneuron reflex discharges (PMRDs) model was used as an experimental paradigm of the ejaculatory expulsion reflex in anaesthetised male rats. A spinal site of action was evaluated by testing the effect of intrathecal delivery of dapoxetine on PMRDs elicited by electric stimulation of the dorsal nerves of the penis (DNP). A supraspinal site of action was evaluated by testing the effect of intravenous administration of dapoxetine on DNP-induced PMRDs in rats with chemical bilateral lesion of the lateral paragigantocellular nucleus (LPGi). RESULTS: Compared with control (NaCl 0.9%, intrathecally), intrathecal injection of dapoxetine (1 and 80 microg) significantly increased amplitude of DNP-elicited PMRDs in a similar fashion than serotonin (5-HT; 10 and 100 microg, intrathecally). In rats having received bilaterally NaCl 0.9% into LPGi, intravenous treatment with dapoxetine (3mg/kg) induced significant delay in PMRD latency and decrease in PMRD amplitude compared with pretreatment values. These effects were abolished in rats having received bilaterally kainic acid into LPGi 1 d before testing. CONCLUSIONS: The present study showed that dapoxetine inhibits ejaculatory expulsion reflex by acting at a supraspinal level with LPGi as a necessary brain structure for this effect.     

Role of peripheral innervation in p-chloroamphetamine-induced ejaculation in anesthetized rats

The occurrence of ejaculation, which consists of 2 distinct phases (emission and expulsion), requires a tight coordination of peripheral autonomic and somatic nerves. However, some aspects of the mechanism of ejaculation are not clearly defined. To clarify this issue, we used the p-chloroamphetamine (PCA)-induced ejaculation model in anesthetized rats and investigated the effects of selective peripheral nerves lesions on seminal vesicle and bulbospongiosus (BS) muscle activities as representing physiological markers of emission and expulsion phases, respectively. In intact rats, ejaculation induced with PCA (intraperitoneal 5 mg/kg) correlated with coordinated increases in seminal vesicle pressure (SVP) and BS electromyographic activity. PCA-induced ejaculation was still observed in rats with bilateral lesion of hypogastric nerves (HNx), lumbar paravertebral sympathetic chain (LSCx), or dorsal nerves of the penis (DNPx). Conversely, bilateral section of pelvic nerves (PNx) or L6-S1 dorsal roots (DRx) abolished PCA-induced ejaculation. The amplitude of SVP increases induced by PCA was reduced in PNx, HNx, and LSCx rats, whereas it was unchanged in DRx and DNPx rats. The time interval between SVP increases and BS muscle contractions induced by PCA was comparable in the different neural lesion groups. In conclusion, PCA initiates both emission and expulsion independently from each other. In this model, afferents conveyed by the pelvic nerves appear to be unnecessary for occurrence of BS muscle contractions but are essential for a complete ejaculatory response.     

帕罗西汀与达帕西汀的对比，治疗早泄的新的选择性5-羟色胺再摄取抑制剂

达帕西汀氢氯化物是一种选择性5-羟色胺再摄取抑制剂,也是第一种被批准可以按需服用治疗早泄的药物。本文目的为研究按需服用达帕西汀（30mg和H60mg）和每日服用帕罗西汀（20mg）对早泄的疗效。研究募集了150名患者进行了长达1个月的研究。患者被分成3组,每组50人。第一组按需服用达帕西汀30mg。第二组按需服用达帕西汀60mg。第三组每日服用帕罗西汀20mg。治疗结束后,我们的结果检测值相对于基准阴道内射精潜伏期（IELT）延长了。与基准IELT相比,帕罗西汀组、30mg达帕西汀组和60mg达帕西汀组的治疗后IELT分别延长了117％（P〈0．01）,117％（P〈0．01）和170％（P〈0．01）。30mg达帕西汀组和帕罗西汀组的IELT增幅相同（P〉0．05）,而60mg达帕西汀组的IELT增幅明显高于30mg达帕西汀组（P〈0．05和帕罗西汀组P〈0．01）。性交前1～3小时服用达帕西汀60mg是针对早泄的非常有效的治疗方法。然而,与当前普遍使用的帕罗西汀相比,达帕西汀30mg疗效并不显著。     

A prospective randomized study to compare pelvic floor rehabilitation and dapoxetine for treatment of lifelong premature ejaculation

Premature ejaculation (PE) is the most common male sexual disorder. We compared pelvic floor muscle rehabilitation to on-demand treatment with the selective serotonin reuptake inhibitor dapoxetine in 40 men with lifelong PE (baseline intra-vaginal ejaculatory latency time (IELT) ≤1 min). Subjects were randomized into the following two treatment groups: (1) PFM rehabilitation or (2) 30 or 60 mg of on-demand dapoxetine. Total treatment time for both groups was 12 weeks, at the end of which, IELT mean values were calculated to compare the effectiveness of the two different therapeutic approaches. At the end of treatment, 11 of the 19 patients (57%) treated with rehabilitation were able to control the ejaculation reflex, with a mean IELT of 126.6 sec (range: 123.6-152.4 sec). In the dapoxetine group, after 12 weeks of therapy, 5 of 8 (62.5%) patients in the 30 mg subgroup and five of seven (72%) in the 60 mg subgroup had an IELT >180 sec (mean: 178.2 and 202.8 sec, respectively). The results obtained in the group treated with pelvic floor rehabilitation are promising, and this treatment represents an important cost reduction if compared to dapoxetine on-demand treatment. The present study confirms the data that are previously available in the literature on the efficacy and safety of the new inhibitor of serotonin reuptake, dapoxetine, as well as proposes and evaluates a new type of physical treatment that may be a viable therapeutic option for treatment of PE.     

Serotonin and premature ejaculation: from physiology to patient management

INTRODUCTION: Premature ejaculation (PE), whose pathophysiology is still not clearly identified, is the most common male sexual dysfunction, yet it remains underdiagnosed and undertreated. The aims of this paper are to provide a scientific and pharmacologic rationale, and to discuss to what extent selective serotonin reuptake inhibitors (SSRIs) can help patients with PE. MATERIALS AND METHODS: A comprehensive evaluation of available published data included analysis of published full-length papers that were identified with Medline and Cancerlit from January 1981 to January 2006. Official proceedings of internationally known scientific societies held in the same time period were also assessed. RESULTS: The central ejaculatory neural circuit comprises spinal and cerebral areas that form a highly interconnected network. The sympathetic, parasympathetic, and somatic spinal centers, under the influence of sensory genital and cerebral stimuli integrated and processed at the spinal cord level, act in synergy to command physiologic events occurring during ejaculation. Experimental evidence indicates that serotonin (5-HT), throughout brain descending pathways, exerts an inhibitory role on ejaculation. To date, three 5-HT receptor subtypes (5-HT1A, 5-HT1B, and 5-HT2C) have been postulated to mediate 5-HT's modulating activity on ejaculation. Pharmacologic manipulation of the serotonergic system has been performed in rats, with the antidepressant selective serotonin reuptake inhibitors (SSRIs) exhibiting the greatest efficacy in delaying ejaculation. The mechanism of action by which SSRIs modulate central 5-HT tone has been studied in depth, but gaps in this knowledge prevent an explanation of the efficacy of acute treatment in delaying ejaculation. Emerging clinical evidence indicates chronic and on-demand dosing of SSRIs has a beneficial effect for the treatment of men with PE, at least for paroxetine. On-demand dapoxetine, and SSRI with a short half-life, recently has been shown to significantly increase intravaginal latency time and PE patient-related outcomes in phase 3 clinical trials. CONCLUSIONS: Nowadays there is no doubt that PE can be treated effectively by SSRIs. Nevertheless their mechanism of action is not yet well understood and deserves more research. In particular it is not understood why all the SSRIs are not equal in terms of their ability to delay ejaculation. Therefore, there is a need for more research to better characterize the mechanism of action of SSRIs as well their clinical benefit in patients affected by PE.     

Electrophysiological evidence for an antinociceptive effect of ketamine in the rat spinal cord

Background : The dissociative anesthetic ketamine also has antinociceptive effects. The mechanism and the site of action of such effect of ketamine have been, however, elusive and controversial. The present study was conducted to examine the effect of systemically administered ketamine on spinal nociceptive transmission.
Methods : We investigated and compared the effects of ketamine (0.25-8 mg/kg) on the hamstring flexor reflex in intact, lightly anesthetized rats and spinally transected rats. The opioid receptor antagonist naloxone was used to examine the involvement of opioid receptors in the actions of ketamine. Finally, the effects of ketamine on dorsal horn neuronal activity to electrical stimulation of peripheral nerves were also studied.
Results : Ketamine caused similar dose-dependent depression of the hamstring flexor reflex recorded from spinally intact rats and from spinalized rats. Even the highest dose of ketamine failed to influence the monosynaptic reflex. The depressive effect of ketamine on the flexor reflex was not reversed by naloxone. Ketamine i.v. also exerted a relatively selective inhibition of the responses of dorsal horn wide-dynamic-range neurons to C-fiber input of electrical stimulation of the plantar nerve.
Conclusions : Our present results support the notion that ketamine can exert a direct antinociceptive effect in rat spinal cord. Moreover, the data indicated that the spinal antinociceptive effect of ketamine does not involve naloxone-sensitive opioidergic mechanisms.     

The monoamine-mediated antiallodynic effects of intrathecally administered milnacipran, a serotonin noradrenaline reuptake inhibitor, in a rat model of neuropathic pain

Antidepressants are often used to treat neuropathic pain. In the present study, we determined the antiallodynic effects of selective monoamine reuptake inhibitors in the spinal cord in a rat model of neuropathic pain. Mechanical allodynia was produced by tight ligation of the left L5 and L6 spinal nerves and determined by applying von Frey filaments to the left hindpaw. A serotonin noradrenaline reuptake inhibitor, milnacipran, a selective serotonin reuptake inhibitor, paroxetine, or a selective noradrenaline reuptake inhibitor, maprotiline, was administered intrathecally via a chronically implanted catheter. Milnacipran produced dose-dependent antiallodynic effects at doses between 3 microg and 100 microg. The effect lasted for 7 h after injection of 100 microg (P < 0.05). The antiallodynic effect of 30 microg of milnacipran was attenuated by intrathecal coadministration of 30 microg of yohimbine, an alpha(2)-adrenoceptor antagonist, 30 microg of methysergide, a serotonin receptor antagonist, or 30 microg of atropine, a muscarinic receptor antagonist (P < 0.01, respectively). Intraperitoneal administration of milnacipran had no antiallodynic effects at doses of 3 to 30 mg/kg. Antiallodynic effects were not produced by intrathecal administration of paroxetine (10 to 100 microg) or maprotiline (10 to 100 microg). These findings suggest that simultaneous inhibition of serotonin and noradrenaline reuptake in the spinal cord is essential to mediate antiallodynic effects. Milnacipran might be effective for suppression of neuropathic pain.     

Pharmacokinetic and pharmacodynamic features of dapoxetine, a novel drug for 'on-demand' treatment of premature ejaculation

OBJECTIVE: To describe the relationship between the pharmacokinetic and pharmacodynamic properties of dapoxetine, a drug specifically developed for treating premature ejaculation (PE). METHODS: Data from various stages of the clinical development programme were analysed using validated methods for assessing ejaculatory latency. The clinical characteristics were then compared with the pharmacokinetic profile, determined from measured plasma drug concentrations. RESULTS: Pharmacodynamic and pharmacokinetic measurements confirm that 'on demand' dapoxetine has a rapid onset of action and is rapidly cleared after sexual intercourse. CONCLUSION: Dapoxetine may represent the first of a new category of selective serotonin transport inhibitors. Although dapoxetine has pharmacological similarities to other selective serotonin transport inhibitors, its efficacy after acute administration sets it apart and suggests a different mode of action. Its physicochemical and pharmacokinetic properties and its clinical efficacy make dapoxetine suitable for on-demand treatment of PE.     

Penile neuropathy in insulin-dependent diabetes mellitus

The dorsal nerve of the penis has been linked closely to penile erection and response. We measured the nerve conduction velocity of the dorsal nerve of the penis, latency of the bulbocavernosus reflex and pudendal evoked potential in 23 normal men and 20 insulin-dependent diabetics with impotence. The conduction velocity of the dorsal nerve of the penis was significantly slower in diabetic than in normal men and passive gentle elongation of the penis by weight stretching enhanced the slowing. In contrast, the bulbocavernosus reflex and pudendal evoked potential showed no significant differences between the 2 groups. We demonstrate the potential usefulness of measurement of the conduction velocity of the dorsal nerve of the penis in the detection of penile neuropathy.     

Comparative efficacy and safety of drug treatment for premature ejaculation: A systemic review and Bayesian network meta-analysis

To assess the comparative efficacy and safety of drug treatments for premature ejaculation. A systemic review and Bayesian network meta-analysis were executed on randomised controlled trials of drug interventions for premature ejaculation. Intravaginal ejaculation latency time and related adverse effects were outcome measures. A total of 44 RCTs with 11,008 patients were included in our NMA. In therapy <8 weeks, the ranking of drug efficacy was topical creams >selective serotonin reuptake inhibitor (SSRI)+ phosphodiesterase 5 inhibitor (PDE5i) > PDE5i > sertraline > clomipramine > paroxetine > dapoxetine 60 milligram (mg) > dapoxetine 30 mg > fluoxetine>citalopram > duloxetine>placebo. In therapy ≥ 8 weeks, the ranking of drug efficacy was SSRI + PDE5i > topical creams > paroxetine > tramadol > PDE5i > fluoxetine > dapoxetine 60 mg > dapoxetine 30 mg > clomipramine>citalopram > placebo. For total adverse events, clomipramine, dapoxetine 30 mg, dapoxetine 60 mg, paroxetine, PDE5i, SSRI + PDE5i and tramadol had a higher risk than placebo. In conclusion, in ≥8 weeks of therapy, the drug combination of SSRI + PDE5i was the most effective PE therapy. In <8 weeks of therapy, the efficacy of local anaesthetics was best. All drug treatments were ranked better than placebo. In general, drugs with better effects had more obvious side effects.     

神经功能性不射精症诊断和电磁刺激振动按摩治疗的临床研究

目的　探讨功能性不射精症的诊断及有效治疗方法。　方法　在临床实验的基础上 ,用神经电生理技术测定了 2 50例功能性不射精症 (不射精组 )和 40例射精正常者 (对照组 )的阴部神经传导时间及速度 ;对 2 50例诊断为神经功能性不射精症用电磁刺激阴部神经并振动按摩阴茎治疗的同时 ,用神经电生理技术测定其阴部神经传导时间及速度。　结果　不射精组与对照组比较 ,阴部神经传导时间明显延长、传导速度明显减慢( P<0 .0 5)。经电磁刺激并振动按摩治疗 ,2 50例不射精组临床治愈 1 3 6例 ( 54 .4% ) ,显效3 9例 ( 1 5.6 % ) ,好转 2 3例 ( 9.2 % ) ,总有效率为 79.2 %。电磁刺激治疗前后相比 ,阴部神经传导时间及速度均有显著性差异 ( P<0 .0 5) ;治疗后与对照组相比 ,相应指标均无显著性差异 ( P>0 .0 5)。　结论　由于功能性不射精症的阴部神经传导性减退 ,难以达到射精阈值和触发射精反射 ,因此可定义或诊断为神经功能性不射精症。经过反复阴部神经电磁刺激并阴茎振动按摩治疗后 ,阴部神经传导性提高 ,易达射精阈值而触发射精反射     

Evolving therapeutic strategies for premature ejaculation: The search for on-demand treatment �C topical versus systemic

Premature ejaculation (PE) is a common sexual dysfunction affecting 20% to 30% of men worldwide. Definitions of PE vary, but it is typically characterized by short intravaginal ejaculatory latency time (IELT) with concomitant sexual dissatisfaction and distress. PE may be lifelong or acquired, but its etiology remains unclear. Treatment of PE typically involves pharmacotherapy, particularly when lifelong. Although there are numerous reports on the off-label use of selective serotonin reuptake inhibitors (SSRIs) and other compounds, only 2 treatments have been evaluated in randomized controlled phase 3 clinical trials: PSD502 and dapoxetine (SSRI). Both significantly improved IELT and patient-reported outcome domains of ejaculatory control, sexual satisfaction, and distress as measured by the index of premature ejaculation (IPE), compared with placebo. They constitute the focus of this review. Evidence demonstrated that PSD502, dapoxetine and other SSRIs all significantly improve the symptoms of PE. Systemic use of SSRIs presents risks associated with the known pharmacology of this class. PSD502 allows for topical on-demand treatment applied applied immediately before intercourse, and is not associated with systemic adverse events.     

Neuroanatomy of the male urethra and perineum

OBJECTIVE: To describe the topography of the perineal nerves from their pudendal origin to their course into the male genitalia, with specific attention on the course of the perineal nerve along the ventral penis, including branches into bulbospongiosus muscle and corpus spongiosum. MATERIALS AND METHODS: The study comprised 18 normal human fetal penile specimens at 17.5-38 weeks of gestation (determined by fetal heel-to-toe length). Specimens were fixed in formalin, embedded in paraffin wax and serially sectioned at 6 micro m. The penile specimens contained the whole penis from the glans to the crural bodies, beneath the pubic arch and the perineum up to the anal verge. Immunocytochemistry was assessed on selected sections with antibodies against the neuronal markers S-100 and nitric oxide synthase (nNOS). Three-dimensional computer reconstruction of serial sections allowed an in-depth analysis of the neuroanatomy of the fetal penis, perineum and surrounding structures. RESULTS: After the pudendal nerve leaves the pudendal canal it gives rise to the perineal nerve branches in the ischiorectal fossa. Perineal nerves travel alongside the ischiocavernous and bulbospongiosus muscles and before reaching the latter, nerve branches course into the bulbospongiosus muscle. During its pathway within this muscle, fine nerve fibres course into the corpus spongiosum by piercing through the junction of the muscle. At the penoscrotal area, the perineal nerves give branches to the scrotum, funnelling into the interscrotal septum. Perineal nerves continue their pathway over the ventral side of penis covering the ventral surface of corpus spongiosum. Branches of the dorsal nerve of the penis at the junction of corpus cavernosum and corpus spongiosum assemble into a network with the perineal nerves. All perineal nerves from their main trunk at the ischiorectal fossa until their interaction with dorsal nerve of penis at the base of penis were nNOS negative. After the interaction with the dorsal nerve of penis, they become nNOS positive. CONCLUSION: Integrating neuroanatomical knowledge about the perineal nerves and their communication with the dorsal nerve of penis should facilitate a strategic approach to reconstructive procedures on the penis. Special care should be taken at the junction between the corpora cavernosa and spongiosa, where the dorsal nerve joins the perineal nerve, and at the proximal bulbospongiosus muscle, thereby protecting the fine nerves piercing into the cavernosa spongiosa.     

Inhibiting the hyperreflexic bladder with electrical stimulation in a spinal animal model

Uninhibited bladder contractions are a problem in spinal cord injured patients. Accordingly, methods using electrical stimulation to inhibit the bladder were investigated in chronic spinal cord injured (C6-T1) male cats. In unanesthetized, restrained animals, spontaneous bladder contractions were observed after the bladder was filled above the micturition threshold. In 3 of the 5 cats studied, this bladder activity could be inhibited with stimulation of either sacral nerves or pudendal nerves. Pudendal nerve stimulation, however, was more selective than sacral nerve stimulation for inhibition with fewer side effects such as leg spasms. Tibial nerve stimulation was ineffective and caused leg spasms and increased bladder activity. Finally, high-frequency stimulation (1,000 Hz) of the sacral nerves was shown to block bladder contractions in 2 of 3 cats investigated. However, this method had adverse side effects such as leg flexion and secondary bladder contractions. We conclude that pudendal nerve/pelvic floor stimulation at low frequency is a relatively effective method in this model.     

Review and update of the anatomy of the penis

The knowledge of penile anatomy is basic to perform a proper diagnosis and direct the most adequate treatment of the various diseases that may appear: urethral stenosis, erectile dysfunction, congenital or acquired penile curvature, etc.; being its anatomical knowledge essential for a proper surgical management. The penis is the male organ involved in both voiding and sexual functions: the body of the penis is composed by three erectile bodies, (i.e the deep structures): the corpora cavernosa and the corpus spongiosum, this last surrounding and covering the urethra. Buck's fascia is in relation to the deep structures of the penis. The superficial fascia, dartos, is made up from a more areolar tissue and is in relation to skin and vessels. The vascularization of the deep structures comes from the common penile artery, a branch of the internal pudendal artery. Penile blood drains through three venous systems: superficial, intermediate and deep systems. Pudendal nerves are in charge of the sensitive and motor somatic innervations. Cavernosal nerves are a combination of parasympathetic and sympathetic afferent fibers, corresponding to the nerves of the autonomic system of the penis.     

选择性阴茎背神经分支切断术治疗原发性早泄

目的:评价选择性阴茎背神经分支切断术治疗原发性早泄(PPE)的安全性和有效性。方法:2003年9月～2006年12月,对483例PPE实施了选择性阴茎背神经分支切断术,患者年龄21～71岁,平均32岁。术中保留两条分支,其余分支均予以切除。切除分支3支者89例,4支者183例,5支者125例,6支者38例,7支者32例,8支者12例,9支者3例,10支者1例。手术后4周开始性生活,随访3～36月。结果:术后所有病例阴茎敏感性均下降,射精潜伏期延长显效352例,好转93例,无效38例,总有效率92.13%。无切口感染,无切口出血,无勃起功能障碍。结论:选择性阴茎背神经切断术致阴茎敏感性下降效果确切,治疗PPE安全、有效。     

Electrical stimulation of the rat lumbar spine induces reflex action potentials in the nerves to the lower abdomen

STUDY DESIGN: The distribution of the nerve action potentials reflexively elicited by electrical stimulation of the lumbar spine was investigated in rats. OBJECTIVES: To elucidate the relation between the lumbar spine and other body regions that compose the spinal reflex. SUMMARY OF BACKGROUND DATA: The hypothesis was that the ventral portion of the L5-L6 disc spatially corresponds to the groin. METHODS: In Experiments 1 and 2, wire electrodes were placed 1) in the ventral and dorsal portions of the disc, facet joint, and muscle fascia at L5-L6, and 2) in the ventral portions of L3-L4, L4-L5, L5-L6, and L6-S discs. A needle electrode was inserted in the L5-L6 disc by 0.4-mm increments, and action potentials were serially recorded from the genitofemoral nerve. RESULTS: Experiments 1 and 2: Reflex action potentials were elicited in the iliohypogastric (T13 and L1), ilioinguinal (L1), and genitofemoral (L2) nerves. Experiment 1: Stimulation of the disc induced reflex discharges significantly more frequently than stimulation of the facet joint and muscle fascia. Experiment 2: The more cranial the disc stimulated, the more frequently the reflex discharge was induced in the iliohypogastric nerve. Experiment 3: The depth of stimulation did not influence the size of the reflex action potential. CONCLUSIONS: Electrical stimulation of the lumbar disc and facet joint induced reflex discharges in the nerves to the lower abdominal regions. It was postulated that the reflex discharges are related to muscle contraction resulting in referred pain in the loin and groin.     

Bladder inhibition or voiding induced by pudendal nerve stimulation in chronic spinal cord injured cats

AIMS: To investigate pudendal-to-bladder spinal reflexes in chronic spinal cord injured (SCI) cats induced by electrical stimulation of the pudendal nerve. METHODS: Bladder inhibition or voiding induced by pudendal nerve stimulation at different frequencies (3 or 20 Hz) was studied in three female, chronic SCI cats under alpha-chloralose anesthesia. RESULTS: Voiding induced by a slow infusion (2-4 ml/min) of saline into the bladder was very inefficient (voiding efficiency=7.3%+/-0.9%). Pudendal nerve stimulation at 3 Hz applied during the slow infusion inhibited reflex bladder activity, and significantly increased bladder capacity to 147.2+/-6.1% of its control capacity. When the 3-Hz stimulation was terminated, voiding rapidly occurred and the voiding efficiency was increased to 25.4+/-6.1%, but residual bladder volume was not reduced. Pudendal nerve stimulation at 20 Hz induced large bladder contractions, but failed to induce voiding during the stimulation due to the direct activation of the motor pathway to the external urethral sphincter. However, intermittent pudendal nerve stimulation at 20 Hz induced post-stimulus voiding with 78.3+/-12.1% voiding efficiency. The voiding pressures (39.3+/-6.2 cmH2O) induced by the intermittent pudendal nerve stimulation were higher than the voiding pressures (23.1+/-1.7 cmH2O) induced by bladder distension. The flow rate during post-stimulus voiding induced by the intermittent pudendal nerve stimulation was significantly higher (0.93+/-0.04 ml/sec) than during voiding induced by bladder distension (0.23+/-0.07 ml/sec). CONCLUSIONS: This study indicates that a neural prosthetic device based on pudendal nerve stimulation might be developed to restore micturition function for people with SCI.     

Dapoxetine, a novel treatment for premature ejaculation, does not have pharmacokinetic interactions with phosphodiesterase-5 inhibitors

Potential pharmacokinetic interactions between dapoxetine, a serotonin transporter inhibitor developed for the treatment of premature ejaculation (PE), and the phosphodiesterase-5 inhibitors tadalafil and sildenafil, agents used in the treatment of erectile dysfunction (ED), were investigated in an open-label, randomized, crossover study (n=24 men) comparing dapoxetine 60 mg, dapoxetine 60 mg+tadalafil 20 mg, and dapoxetine 60 mg+sildenafil 100 mg. Plasma concentrations of dapoxetine, tadalafil, and sildenafil were determined by liquid chromatography-tandem mass spectrometry. Tadalafil did not affect the pharmacokinetics of dapoxetine, whereas sildenafil increased the dapoxetine AUCinf by 22%; these effects were deemed not clinically important. Dapoxetine did not appear to affect the pharmacokinetics of tadalafil or sildenafil. Most adverse events were mild in nature. Thus, dapoxetine has no clinically important pharmacokinetic interactions with tadalafil or sildenafil, and the combinations are well tolerated.     

Afferent fibers of the pudendal nerve modulate sympathetic neurons controlling the bladder neck

AIMS: Pudendal nerve stimulation is known to have a potential modulative effect on bladder function. However, even if its efficiency has been established for various neurogenic and non-neurogenic bladder dysfunctions, the underlying neuronal mechanism, and the involved pathways in humans remain unknown. In this prospective study we focused on the effects of pudendal nerve stimulation in complete spinal cord injured patients to identify neuromodulative processes that occur on spinal level. METHODS: Twenty complete spinal male presenting with upper motor neuron lesion and neurogenic incontinence underwent pudendal nerve stimulation. Bladder, bladder neck (BN), and external urethral sphincter (EUS) pressures were continuously recorded with a three channel microtip pressure transducer catheter. Fifty six pudendal stimulations using biphasic rectangular impulses (0.2 ms, 10 Hz) with intensities up to 100 mA were applied to the dorsal penile nerve. In six patients, 18 stimulations were repeated after intravenous (i.v.) administration of 7 mg phentolamine. RESULTS: Mean BN and EUS pressure increased during stimulation significantly (P < 0.001). The latencies to the EUS responses range between 27 and 41 ms and those to the BN responses between 188 and 412 ms. Phentolamine decreased initial BN pressure and reduced the pressure rise during stimulation significantly (P < 0.05). CONCLUSIONS: Pudendal nerve stimulation evoked somatic responses in the EUS and autonomic responses in the smooth muscle sphincter controlling the BN. Longer latencies of the BN responses and the sensitivity to the alpha-blocking agent phentolamine suggest that sympathetic alpha-adrenergic fibers are involved. Somatic afferent fibers of the pudendal nerve are supposed to project on sympathetic thoracolumbar neurons to the BN and modulate their function. This neuromodulative effect works exclusively at the spinal level and appears to be at least partly responsible for BN competence and at least continence.