Emerging treatments for premature ejaculation: focus on dapoxetine

A Comparative Study of the Efficacy of Levosulpiride versus Paroxetine in Premature Ejaculation

Background:

Premature ejaculation (PME) can be defined as a lack in the normal voluntary control over ejaculation. It is the most common sexual dysfunction encountered by the male populace. In general, these patients presents with distress. Hence, a novel treatment to eliminate their problem is required. Although the role of SSRI has already been established, the high discontinuation rate and other types of sexual dysfunctions associated with SSRIs reduce their efficacy in controlling this menace. Levosulpiride is a new drug indicated in treatment of PE.

Aims and Objectives:

The objective is to study the efficacy of levosulpiride; paroxetine and their comparison in patients of PE.

Methodology:

Index of premature ejaculation (IPE) and intravaginal ejaculation latency time (IELT) were used. A total of 36 patients (18 in each group) were included. The patients were assessed at baseline; at 4 weeks’ and at 8 weeks’ interval.

Results:

On comparison the score of IPE in domains of ejaculation control, sexual satisfaction, and the total score of IPE were statistically significant on all the three visits. However, the distress score of IPE and the IELT score were statistically not significant between the two groups.

Conclusion:

No doubt both agents are efficacious in patients of PME but paroxetine is more efficacious than levosulpiride. At the same time, levosulpiride is a lesser studied and used drug hence more research should be done for it.

Premature Ejaculation: Aetiology and Treatment Strategies

Premature ejaculation (PE) is a highly prevalent male sexual dysfunction that is often neglected, presenting a currently unmet therapeutic need. The classification of PE has historically been varied and at times ambiguous, contributing to inaccurate prevalence estimates. This review uses the International Society for Sexual Medicine (ISSM) definition of PE, which includes reduced ejaculatory latency, lack of control and associated negative personal consequences. Patient assessment and management options differ depending on the classification of PE and it is the role of the clinician to appropriately classify patients and be aware of the correct management strategies. This review provides an overall background of PE in terms of classification and underlying physiology, patient assessment and management strategies along with the scientific rationale for treatment. Patients with lifelong and acquired PE are most likely to benefit from combination therapy of pharmacological treatment in the form of selective serotonin re-uptake inhibitor dapoxetine, psychosexual behavioural therapy and psychological therapy.

Dapoxetine and the treatment of premature ejaculation

Background

Premature ejaculation (PE) is the most common male sexual complaint. Off-label oral selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed for the treatment of PE. Dapoxetine is a short-acting SSRI specifically designed for on-demand use. The objective of this communication is to summarize the clinical and physiological evidence regarding the role of the serotonergic pathway and specifically dapoxetine in the treatment of PE.

Methods

A PubMed search was conducted on articles reporting data on dapoxetine for the treatment of PE. Articles describing the pathophysiology and treatment options for PE were additionally included for review.

Results

The etiology of PE is multi-factorial in nature. There are many treatment options for PE such as psychological/behavioral therapy, topical anesthetic agents, phosphodiesterase type 5 (PDE-5) inhibitors, and tramadol hydrochloride. SSRIs play a major role in PE treatment. Animal and clinical studies in addition to its pharmacokinetic document dapoxetine’s clinical efficacy and safety for on-demand treatment of PE.

Conclusions

Dapoxetine demonstrates clinical efficacy and a favorable side effect profile. Dapoxetine is currently the oral drug of choice for on-demand treatment of PE.

Comparison of paroxetine and dapoxetine, a novel selective serotonin reuptake inhibitor in the treatment of premature ejaculation

Dapoxetine hydrochloride is a selective serotonin reuptake inhibitor and the first drug approved for the on-demand treatment of premature ejaculation (PE). Our objective in this study was to characterize the efficacy of on-demand dapoxetine (30 and 60 mg) and daily paroxetine (20 mg) usage in treating PE. We conducted a 1 month study involving a total of 150 patients. Patients were divided into three groups of 50. Group 1 were treated with on-demand dapoxetine (30 mg), Group 2 with on-demand dapoxetine (60 mg) and Group 3 with daily paroxetine (20 mg). Our outcome measurement was increased from baseline intravaginal ejaculatory latency time (IELT) after treatment. The IELT increased from baseline to posttreatment by 117%, 117% and 170% in the paroxetine group (P < 0.01), 30 mg dapoxetine group (P < 0.01) and 60 mg dapoxetine group (P < 0.01), respectively. The increase from baseline IELT were similar for the 30 mg dapoxetine and paroxetine groups (P > 0.05), while the 60 mg dapoxetine group had a larger posttreatment IELT increase compared with the 30 mg dapoxetine (P < 0.05) and paroxetine (P < 0.01) groups. Dapoxetine (60 mg) 1-3 h before planned intercourse is a very effective treatment modality for PE. However, an on-demand dose of 30 mg dapoxetine is no more effective than the currently prescribed paroxetine treatment.

Effects of dapoxetine on cloned Kv1.5 channels expressed in CHO cells

The effects of dapoxetine were examined on cloned Kv1.5 channels stably expressed in Chinese hamster ovary cells using the whole-cell patch clamp technique. Dapoxetine decreased the peak amplitude of Kv1.5 currents and accelerated the decay rate of current inactivation in a concentration-dependent manner with an IC ( 50 ) of 11.6 μM. Kinetic analysis of the time-dependent effects of dapoxetine on Kv1.5 current decay yielded the apparent association (k (+1 )) and dissociation (k (-1 )) rate constants of 2.8 μM(-1) s(-1) and 34.2 s(-1), respectively. The theoretical K ( D ) value, derived by k (-1 )/k (+1 ), yielded 12.3 μM, which was reasonably similar to the IC ( 50 ) value obtained from the concentration-response curve. Dapoxetine decreased the tail current amplitude and slowed the deactivation process of Kv1.5, which resulted in a tail crossover phenomenon. The block by dapoxetine is voltage-dependent and steeply increased at potentials between -10 and +10 mV, which correspond to the voltage range of channel activation. At more depolarized potentials, a weaker voltage dependence was observed (δ=0.31). Dapoxetine had no effect on the steady-state activation of Kv1.5 but shifted the steady-state inactivation curves in a hyperpolarizing direction. Dapoxetine produced a use-dependent block of Kv1.5 at frequencies of 1 and 2 Hz and slowed the time course for recovery of inactivation. These effects were reversible after washout of the drug. Our results indicate that dapoxetine blocks Kv1.5 currents by interacting with the channel in both the open and inactivated states of the channel.

Dapoxetine: an evidence-based review of its effectiveness in treatment of premature ejaculation

Premature ejaculation (PE) is a major issue in male sexual health. The global prevalence of PE is estimated to be between 20% and 40%, making it the most common sexual dysfunction in men. PE causes distress and reduced quality of life for patients and has a negative impact on interpersonal relationships. Historically, it has been treated with cognitive therapy, behavioral methods, and off-label use of selective serotonin reuptake inhibitors usually used to treat depression and other psychological disorders. Dapoxetine is a selective serotonin reuptake inhibitor specifically designed to treat PE. This paper reviews the current evidence for use of dapoxetine in the treatment of PE in adult men. There is substantial evidence that dapoxetine 30 mg or 60 mg taken “on-demand” results in a significant increase in intravaginal ejaculatory latency time when compared with placebo. Patient-reported outcomes are clearly improved relative to placebo following dapoxetine therapy, indicating greater control over ejaculation, more satisfaction with intercourse, less ejaculation-related distress, and, importantly, significantly reduced interpersonal difficulty. These data were supported by consistent reports of improvement in Clinical Global Impression of change in PE following treatment with dapoxetine. Further studies are needed to evaluate long-term efficacy and health economics. The unique pharmacology of dapoxetine makes it ideal for on-demand dosing, and the clinical evidence shows dapoxetine to be an efficacious and tolerable treatment for lifelong and acquired PE.

Serotonergic lesions of the periaqueductal gray, a primary source of serotonin to the nucleus paragigantocellularis, facilitate sexual behavior in male rats

While selective serotonin reuptake inhibitors (SSRIs) are widely used to treat anxiety and depression, they also produce profound disruptions of sexual function including delayed orgasm/ejaculation. The nucleus paragigantocellularis (nPGi), a primary source of inhibition of ejaculation in male rats, contains receptors for serotonin (5-HT). The ventrolateral periaqueductal gray (vlPAG) provides serotonin to this region, thus providing an anatomical and neurochemical basis for serotonergic regulation of the nPGi. We hypothesize that 5-HT acting at the nPGi could underlie the SSRI-induced inhibition of ejaculation in rodents. To this end, we produced 5-HT lesions of the source of 5-HT to the nPGi (the vlPAG) and examined sexual behavior. Removing the source of 5-HT to the nPGi facilitated genital reflexes, but not other aspects of sexual behavior, consistent with our hypothesis. Namely, 5-HT lesions produced a significant increase in the mean number of ejaculations and a significant decrease in ejaculation latency as compared to sham lesioned animals, while latency to mating and the post-ejaculatory interval did not differ. These data suggest that the serotonergic vlPAG-nPGi pathway is an important regulatory mechanism for the inhibition of ejaculation in rats and supports the hypothesis that this circuit contributes to SSRI-induced inhibition of ejaculation.

Dapoxetine: in premature ejaculation

Dapoxetine, a selective serotonin reuptake inhibitor, is the first oral pharmacological agent indicated for the treatment of men aged 18-64 years with premature ejaculation. In four randomized, double-blind, placebo-controlled, multicentre studies of 12-24 weeks' duration, oral dapoxetine 30 or 60 mg (administered as needed) was effective in the treatment of men with premature ejaculation, inducing significantly (p < 0.001) greater improvements from baseline than placebo in the primary efficacy endpoint (mean intravaginal ejaculatory latency time [IELT] or mean average IELT [defined as the average of IELT values over the previous 4 weeks], as measured by the female partner utilizing a stopwatch). For the most part, dapoxetine recipients achieved significantly better outcomes than placebo recipients with regard to the secondary endpoints, including the Premature Ejaculation Profile (PEP) domains and the Clinical Global Impression or Patient Global Impression ratings of change in premature ejaculation, across these clinical studies. The beneficial effects of dapoxetine therapy on the perceived control over ejaculation and satisfaction with sexual intercourse PEP domains were sustained in a 9-month noncomparative extension phase of two identical 12-week, double-blind studies. Oral dapoxetine therapy for up to 12 months was generally well tolerated in men with premature ejaculation, with the nature of treatment-emergent adverse events generally similar across the clinical studies and between dapoxetine and placebo.

Recent advances in the treatment of premature ejaculation

Premature ejaculation (PE) is the most common sexual problem affecting men. It can affect men at all ages and has a serious impact on the quality of life for men and their partners. Currently there are no pharmaceutical agents approved for use in the UK, and so all drugs used for this condition are off label. Behavioral therapy has been used to treat PE, but the results are not durable once therapy has been concluded. Several topical therapies have been used including severance-secret (SS) cream, lignocaine spray, lidocaine-prilocaine cream and lidocaine-prilocaine spray (TEMPE). There has been recent interest in the selective serotonin reuptake inhibitors (SSRIs) for the treatment of PE, due to the fact that one of their common side effects is delayed ejaculation. Currently used SSRIs have several non-sexual side effects and long half lives, therefore there has been interest in developing a short acting, efficacious SSRI that can be used on-demand for PE. Dapoxetine has been recently evaluated for the treatment of PE by several groups, and results so far appear promising.