Pharmacokinetics and tolerability of DA-8031, a novel selective serotonin reuptake inhibitor for premature ejaculation in healthy male subjects

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.

Pharmacokinetics, Tolerability and Pharmacogenetics of DA-8031 After Multiple Ascending Doses in Healthy Male Subjects

Purpose

DA-8031 is a novel selective serotonin reuptake inhibitor for the treatment of premature ejaculation. This study investigated the pharmacokinetics, safety and tolerability of multiple oral doses of DA-8031. In addition, a genetic analysis was explored to evaluate the effect of genetic polymorphisms on the pharmacokinetics of DA-8031.

Subjects and Methods

A dose block-randomized, double-blind, placebo-controlled study was conducted in 3 dose groups with 20, 30 and 40 mg of DA-8031. Healthy male subjects were randomized to DA-8031 or placebo at a 4:1 ratio in each dose group of 10 subjects by oral administration once daily for 7 consecutive days. Serial blood and urine samples were collected for the pharmacokinetic evaluation, and the pharmacokinetic-related genes were analyzed by DMET^TM plus. A safety evaluation was conducted including adverse events (AEs) monitoring and 12-lead electrocardiogram (ECG).

Results

The plasma DA-8031 concentration reached the maximum concentration (C_max) in 2.2 to 3.0 h and was eliminated with a mean half-life of 25.5 to 26.7 h at steady state. The accumulation index of DA-8031 ranged 2.3 to 2.8. The systemic exposure of DA-8031 of the CYP2D6 intermediate metabolizer (IM) was significantly higher compared to the CYP2D6 poor metabolizer (PM). There were no clinically significant QTc interval changes, and all the adverse events were mild.

Conclusion

After multiple oral doses of DA-8031 20, 30, and 40 mg in this study, the systemic exposure of DA-8031 increased in a more than dose-proportional manner with the increasing doses, and DA-8031 was generally well tolerated. In addition, the genetic polymorphisms of CYP2D6 have an impact on the pharmacokinetics of DA-8031.

Selective serotonin re-uptake inhibitors for premature ejaculation in adult men

BACKGROUND

Premature ejaculation (PE) is a common problem among men that occurs when ejaculation happens sooner than a man or his partner would like during sex; it may cause unhappiness and relationship problems. Selective serotonin re-uptake inhibitors (SSRIs), which are most commonly used as antidepressants are being used to treat this condition.

OBJECTIVES

To assess the effects of SSRIs in the treatment of PE in adult men.

SEARCH METHODS

We performed a comprehensive search using multiple databases (the Cochrane Library, MEDLINE, Embase, Scopus, CINAHL), clinical trial registries, conference proceedings, and other sources of grey literature, up to 1 May 2020. We applied no restrictions on publication language or status.

SELECTION CRITERIA

We included only randomized controlled clinical trials (parallel group and cross-over trials) in which men with PE  were administered SSRIs or placebo. We also considered 'no treatment' to be an eligible comparator but did not find any relevant studies.

DATA COLLECTION AND ANALYSIS

Two review authors independently classified and abstracted data from the included studies. Primary outcomes were participant-perceived change with treatment, satisfaction with intercourse and study withdrawal due to adverse events. Secondary outcomes included self-perceived control over ejaculation, participant distress about PE, adverse events and intravaginal ejaculatory latency time (IELT). We performed statistical analyses using a random-effects model. We rated the certainty of evidence according to GRADE.

MAIN RESULTS

We identified 31 studies in which 8254 participants were randomized to receiving either SSRIs or placebo. Primary outcomes: SSRI treatment probably improves self-perceived PE symptoms (defined as a rating of 'better' or 'much better') compared to placebo (risk ratio (RR) 1.92, 95% confidence interval (CI) 1.66 to 2.23; moderate-certainty evidence). Based on 220 participants per 1000 reporting improvement with placebo, this corresponds to 202 more men per 1000 (95% CI 145 more to 270 more) with improved symptoms with SSRIs.  SSRI treatment probably improves satisfaction with intercourse compared to placebo (defined as a rating of 'good' or 'very good'; RR 1.63, 95% CI 1.42 to 1.87; moderate-certainty evidence). Based on 278 participants per 1000 reporting improved satisfaction with placebo, this corresponds to 175 more (117 more to 242 more) per 1000 men with greater satisfaction with intercourse with SSRIs. SSRI treatment may increase treatment cessations due to adverse events compared to placebo (RR 3.80, 95% CI 2.61 to 5.51; low-certainty evidence). Based 11 study withdrawals per 1000 participants with placebo, this corresponds to 30 more men per 1000 (95% CI 17 more to 49 more) ceasing treatment due to adverse events with SSRIs.  Secondary outcomes: SSRI treatment likely improve participants' self-perceived control over ejaculation (defined as rating of 'good' or 'very good') compared to placebo (RR 2.29, 95% CI 1.72 to 3.05; moderate-certainty evidence). Assuming 132 per 1000 participants perceived at least good control, this corresponds to 170 more (95 more to 270 more) reporting at least good control with SSRIs.  SSRI probably lessens distress (defined as rating of 'a little bit' or 'not at all') about PE (RR 1.54, 95% CI 1.26 to 1.88; moderate-certainty evidence). Based on 353 per 1000 participants reporting low levels of distress, this corresponds to 191 more men (92 more to 311 more) per 1000 reporting low levels of distress with SSRIs.  SSRI treatment probably increases adverse events compared to placebo (RR 1.71, 95% CI 1.48 to 1.99; moderate-certainty evidence). Based on 243 adverse events per 1000 among men receiving placebo, this corresponds to 173 more (117 more to 241 more) men having an adverse event with SSRIs.  SSRI treatment may increase IELT compared to placebo (mean difference (MD) 3.09 minutes longer, 95% CI 1.94 longer to 4.25 longer; low-certainty evidence).

AUTHORS' CONCLUSIONS

SSRI treatment for PE appears to substantially improve a number of outcomes of direct patient importance such as symptom improvement, satisfaction with intercourse and perceived control over ejaculation when compared to placebo. Undesirable effects are a small increase in treatment withdrawals due to adverse events as well as substantially increased adverse event rates. Issues affecting the certainty of evidence of outcomes were study limitations and imprecision.

Phase I and phase II clinical trials for the treatment of male sexual dysfunction-a systematic review of the literature

INTRODUCTION

The prevalence of sexual dysfunctions has increased over the last decades; despite a number of available treatments for erectile dysfunction (ED), premature ejaculation (PE), and Peyronie's disease (PD), still several unmet therapeutic needs deserve to be fulfilled. The aim of this review is to detail on phase I and II clinical trials investigating novel medical treatments for ED, PE, and PD.

AREAS COVERED

We conducted a systematic review of the literature including both published and ongoing phase I and II registered trials focused on medical treatment of ED, PE, and PD during the last 5 years. A total of 35 trials have been identified. Most studies (63%) investigated ED treatments and 26% were still ongoing. Stem cells (SCs) therapy was assessed in 28% of trials.

EXPERT OPINION

SCs therapy represent a promising treatment for ED although only few patients have been treated to date. Likewise, the oral selective oxytocin receptor antagonists for treating PE showed excellent safety profile and deserve further investigations in phase III trials. Preliminary results of novel topical treatments for PD with fibrinolytic and antiinflammatory drugs are encouraging, but urgently need to be confirmed in large placebo-controlled trials.

Premature ejaculation: challenging new and the old concepts

Premature ejaculation remains a difficult condition to manage for patients, their partners, and the clinician. Whilst prevalence rates are estimated to be 20-40%, determining a diagnosis of premature ejaculation is difficult, as the definition remains both subjective and ill-defined in the clinical context. As our understanding of the ejaculatory pathway has improved, new opportunities to treat the condition have evolved with mixed results. In this review, we explore some of these controversies surrounding the aetiology, diagnosis, and treatment of this condition and discuss potential novel therapeutic options.