Bremelanotide for female sexual dysfunctions in premenopausal women: a randomized, placebo-controlled dose-finding trial

Small Effects, Questionable Outcomes: Bremelanotide for Hypoactive Sexual Desire Disorder

Efficacy outcomes are only informative to the extent that they are validated. We examined the measurement properties of efficacy measures from the phase III ("RECONNECT") bremelanotide trials for hypoactive sexual desire disorder (HSDD) in women. Continuous efficacy outcomes, including a) the Female Sexual Function Index (FSFI) and its Desire domain (FSFI-D) and b) the Female Sexual Distress Scale-Desire/Arousal/Orgasm (FSDS-DAO) and its item assessing distress due to low desire (FSDS-DAO #13) have questionable, at best, validity evidence for women with HSDD. We found no validity evidence for previously published categorical treatment response outcomes from the RECONNECT trials. All efficacy results should be reported, but results on 8 of the 11 clinicaltrials.gov-specified efficacy outcomes were heretofore unpublished (including FSDS-DAO total score, FSFI total score, FSFI arousal domain, and items from the Female Sexual Encounter Profile-Revised). We analyzed these outcomes, upon which effect sizes ranged from nil to small. Several other continuous and categorical outcomes generated modest apparent benefits, though nearly all of these outcomes were likely derived post-hoc. Across RECONNECT trial data from two prior publications and the current study, bremelanotide's benefits are statistically modest and limited to outcomes for which scant evidence of validity among women with HSDD exists.

A Comprehensive Review of Novel FDA-Approved Psychiatric Medications (2018-2022)

Mental health disorders are among the top leading causes of disease burden worldwide and many patients have high levels of treatment resistance. Even though medications offer improvement to some patients, antidepressants are only effective in about half of those treated, and schizophrenia is treatment-refractory in about one-third of patients. One way to combat this disparity is to improve medication development and discovery for psychiatric disorders through evidence-based research. Recently, most psychiatric medications approved by the United States Food and Drug Administration (FDA) are for increased tolerability or extended release. Because of the slow, incremental progress, there is a pressing need to explore novel medications with new indications or mechanisms of action to treat the expanding population with mental disorders, especially in those who are fully or partially recalcitrant to first-line medication options. This review aims to present the newest FDA medications with new indications, establish the clinical need for each, and discuss future directions in drug development. We searched and reviewed novel psychiatric medications approved by the FDA from 2018 to 2022. We then analyzed each medication in the United States Clinical Trials Registry and gathered updated results for efficacy and safety information. We also searched PubMed/MEDLINE (Medical Literature Analysis and Retrieval System Online), Scopus, Web of Science, Elsevier, and Google Scholar to understand how these new indications met current clinical needs. Finally, we inquired about related technological implications that will lead the field of psychopharmacology now and in the years to come. We found 12 novel psychiatric medications approved by the FDA from 2018 to 2022, representing a very small percentage of the total FDA approvals during that period. These psychiatric medications with novel mechanisms or improved efficacy and safety  are expected to provide further options for treating mental health disorders; promising results will lead to new patterns of research.

Non-pharmacological and drug treatment of autonomic dysfunction in multiple system atrophy: current status and future directions

Multiple system atrophy (MSA) is a sporadic, fatal, and rapidly progressive neurodegenerative disease of unknown etiology that is clinically characterized by autonomic failure, parkinsonism, cerebellar ataxia, and pyramidal signs in any combination. Early onset and extensive autonomic dysfunction, including cardiovascular dysfunction characterized by orthostatic hypotension (OH) and supine hypertension, urinary dysfunction characterized by overactive bladder and incomplete bladder emptying, sexual dysfunction characterized by sexual desire deficiency and erectile dysfunction, and gastrointestinal dysfunction characterized by delayed gastric emptying and constipation, are the main features of MSA. Autonomic dysfunction greatly reduces quality of life and increases mortality. Therefore, early diagnosis and intervention are urgently needed to benefit MSA patients. In this review, we aim to discuss the systematic treatment of autonomic dysfunction in MSA, and focus on the current methods, starting from non-pharmacological methods, such as patient education, psychotherapy, diet change, surgery, and neuromodulation, to various drug treatments targeting autonomic nerve and its projection fibers. In addition, we also draw attention to the interactions among various treatments, and introduce novel methods proposed in recent years, such as gene therapy, stem cell therapy, and neural prosthesis implantation. Furthermore, we elaborate on the specific targets and mechanisms of action of various drugs. We would like to call for large-scale research to determine the efficacy of these methods in the future. Finally, we point out that studies on the pathogenesis of MSA and pathophysiological mechanisms of various autonomic dysfunction would also contribute to the development of new promising treatments and concepts.

Melanocortin 4 receptor signaling in Sim1 neurons permits sexual receptivity in female mice

Introduction

Female sexual dysfunction affects approximately 40% of women in the United States, yet few therapeutic options exist for these patients. The melanocortin system is a new treatment target for hypoactive sexual desire disorder (HSDD), but the neuronal pathways involved are unclear.

Methods

In this study, the sexual behavior of female MC4R knockout mice lacking melanocortin 4 receptors (MC4Rs) was examined. The mice were then bred to express MC4Rs exclusively on Sim1 neurons (tbMC4RSim1 mice) or on oxytocin neurons (tbMC4ROxt mice) to examine the effect on sexual responsiveness.

Results

MC4R knockout mice were found to approach males less and have reduced receptivity to copulation, as indicated by a low lordosis quotient. These changes were independent of body weight. Lordosis behavior was normalized in tbMC4RSim1 mice and improved in tbMC4ROxt mice. In contrast, approach behavior was unchanged in tbMC4RSim1 mice but greatly increased in tbMC4ROxt animals. The changes were independent of melanocortin-driven metabolic effects.

Discussion

These results implicate MC4R signaling in Oxt neurons in appetitive behaviors and MC4R signaling in Sim1 neurons in female sexual receptivity, while suggesting melanocortin-driven sexual function does not rely on metabolic neural circuits.

An evaluation of bremelanotide injection for the treatment of hypoactive sexual desire disorder

INTRODUCTION

Female sexual response implies a deep intertwining between psychosocial and neurobiological mediators. Regulation of central melanocortin signaling may enhance sexual desire. In premenopausal women with hypoactive sexual desire disorder (HSDD), melanocortin receptor agonist bremelanotide (Vyleesi) has been hypothesized to trigger excitatory brain pathways.

AREAS COVERED

Hereby we summarize bremelanotide's proposed mechanism of action, pharmacokinetics, efficacy and safety data derived from clinical trials. A literature search of peer-reviewed publications on the current evidence on the pharmacotherapy with bremelanotide was performed using the PubMed database.

EXPERT OPINION

Bremelanotide appears to be moderately safe and well-tolerated; the most common adverse reaction is nausea (40%). Although data from clinical trials demonstrated a significant change in validated questionnaires, the overall clinical benefit appears to be modest. However, these results should be interpreted in the light of the dramatic challenges in conducting well-designed clinical trials for female sexual dysfunction, due to the significant placebo effect of pharmacotherapy, and the frequent use of outcome measures that are likely to be highly susceptible to expectation biases, such as long periods of recall of sexual and emotional response.

Pharmacotherapy for female sexual dysfunctions (FSDs): what is on the market and where is this field heading?

INTRODUCTION

Female sexual dysfunctions (FSDs) are common in women of any age and have a huge impact on quality of life and relationships. They have a multifaceted etiology limiting the development of pharmacotherapies with a high rate of effectiveness. Safety issues are also a concern.

AREAS COVERED

The authors report the most recent advances in pharmacotherapy for premenopausal and postmenopausal women with a main focus on hypoactive sexual desire disorders (HSDD) and associated sexual symptoms. Good levels of evidence have emerged for psychoactive agents, such as flibanserin and bremelanotide, as well as hormonal compounds (transdermal testosterone). The authors also report briefly on intravaginal DHEA (prasterone), local estrogen therapy (LET), and ospemifene to manage effectively vulvovaginal atrophy/genitourinary syndrome of menopause (VVA/GSM). In addition, they discuss promising therapeutic options highlighting the main reasons that hamper the availability of new labeled products. Finally, they include the importance of the multimodal approach to address FSDs.

EXPERT OPINION

Approved pharmacotherapies for FSD are limited. Validated multidimensional instruments and adequate objective measures of physical and mental responses to sexual external and internal incentives are mandatory to identify women suitable to chronic or on-demand treatments and to assess their pattern of response in research and practice.

Melanocortin 4 receptor agonism enhances sexual brain processing in women with hypoactive sexual desire disorder

BACKGROUND

Hypoactive sexual desire disorder (HSDD) is characterized by a persistent deficiency of sexual fantasies and desire for sexual activity, causing marked distress and interpersonal difficulty. It is the most prevalent female sexual health problem globally, affecting approximately 10% of women, but has limited treatment options. Melanocortin 4 receptor (MC4R) agonists have emerged as a promising therapy for women with HSDD, through unknown mechanisms. Studying the pathways involved is crucial for our understanding of normal and abnormal sexual behavior.

METHODS

Using psychometric, functional neuroimaging, and hormonal analyses, we conducted a randomized, double-blinded, placebo-controlled, crossover clinical study to assess the effects of MC4R agonism compared with placebo on sexual brain processing in 31 premenopausal heterosexual women with HSDD.

RESULTS

MC4R agonism significantly increased sexual desire for up to 24 hours after administration compared with placebo. During functional neuroimaging, MC4R agonism enhanced cerebellar and supplementary motor area activity and deactivated the secondary somatosensory cortex, specifically in response to visual erotic stimuli, compared with placebo. In addition, MC4R agonism enhanced functional connectivity between the amygdala and the insula during visual erotic stimuli compared with placebo.

CONCLUSION

These data suggest that MC4R agonism enhanced sexual brain processing by reducing self-consciousness, increasing sexual imagery, and sensitizing women with HSDD to erotic stimuli. These findings provide mechanistic insight into the action of MC4R agonism in sexual behavior and are relevant to the ongoing development of HSDD therapies and MC4R agonist development more widely.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04179734.

FUNDING

This is an investigator-sponsored study funded by AMAG Pharmaceuticals Inc., the Medical Research Council (MRC) (MR/T006242/1), and the National Institute for Health Research (NIHR) (CS-2018-18-ST2-002 and RP-2014-05-001).

Ligands for Melanocortin Receptors: Beyond Melanocyte-Stimulating Hormones and Adrenocorticotropin

The discovery of melanocortins in 1916 has resulted in more than 100 years of research focused on these peptides. Extensive studies have elucidated well-established functions of melanocortins mediated by cell surface receptors, including MSHR (melanocyte-stimulating hormone receptor) and ACTHR (adrenocorticotropin receptor). Subsequently, three additional melanocortin receptors (MCRs) were identified. Among these five MCRs, MC3R and MC4R are expressed primarily in the central nervous system, and are therefore referred to as the neural MCRs. Since the central melanocortin system plays important roles in regulating energy homeostasis, targeting neural MCRs is emerging as a therapeutic approach for treating metabolic conditions such as obesity and cachexia. Early efforts modifying endogenous ligands resulted in the development of many potent and selective ligands. This review focuses on the ligands for neural MCRs, including classical ligands (MSH and agouti-related peptide), nonclassical ligands (lipocalin 2, β-defensin, small molecules, and pharmacoperones), and clinically approved ligands (ACTH, setmelanotide, bremelanotide, and several repurposed drugs).

MC4R biased signalling and the conformational basis of biological function selections

The MC4R, a GPCR, has long been a major target for obesity treatment. As the most well‐studied melanocortin receptor subtype, the evolutionary knowledge pushes the drug development and structure–activity relationship (SAR) moving forward. The past decades have witnessed the evolution of scientists' view on GPCRs gradually from the control of a single canonical signalling pathway via a bilateral ‘active‐inactive’ model to a multi‐state alternative model where the ligands' binding affects the selection of the downstream signalling. This evolution brings the concept of biased signalling and the beginning of the next generation of peptide drug development, with the aim of turning from receptor subtype specificity to signalling pathway selectivity. The determination of the value structures of the MC4R revealed insights into the working mechanism of MC4R activation upon binding of agonists. However, new challenge has risen as we seek to unravel the mystery of MC4R signalling selection. Thus, more biased agonists and ligands with representative biological functions are needed to solve the rest of the puzzle.

The association between Parkinson's disease and Sexual dysfunction: Clinical correlation and therapeutic implications

Sexual function which comprises of desire, arousal, orgasm and satisfaction and pain, involves coordinated physiologic responses from multiple different pathways. Sexual dysfunction (SD) occurs when these domains of the sexual response cycle are affected. SD is a common but under-recognized non-motor feature in Parkinson's disease (PD), a common age-related neurodegenerative disorder. SD significantly affects the quality of life of PD patients and their partners. Advanced age, gender, hormone deficiency, neuropsychiatric and medical comorbidities contribute to SD in PD. Possible potential pathological mechanisms include vasculogenic, endocrinologic, neurogenic and psychogenic factors. Various therapeutic interventions, both pharmacological and non-pharmacological modalities have been suggested to improve SD in PD. However, erectile dysfunction (ED) is the only SD with evidence-based treatment available. Non-pharmacological therapies are also offering promising evidence in the improvement of SD. A multidisciplinary approach in the assessment, investigation, and treatment is needed to address the real life complex issues (gender and comorbidities, neurobiological, vasoactive, hormonal as well as psychosocial aspects). Future clinical studies with validated and standardized methods in assessing SD as well as experimental models will be necessary for better insight into the pathophysiology. This would facilitate appropriate therapy and improve sexual rehabilitation in PD patients.

Management of Hypertension with Female Sexual Dysfunction

Female sexual dysfunction (FSD) in hypertension has been less studied than male sexual dysfunction, and antihypertensive agents’ impact on female sexual function is not defined. In this review, randomized double-blind clinical trials and cross-sectional studies related to female sexual function in hypertension were analyzed from 1991 to 2021. FSD appeared to be higher in hypertensive women than in normotensive women. Beta-blockers are the only antihypertensive agents with relatively strong evidence of damaging the female sexual function. Angiotensin receptor blockers (ARB) are relatively beneficial to female sexual function. To treat FSD in the presence of hypertension, controlling blood pressure is key, and the administration of angiotensin receptor blockers is preferred. In addition to controlling blood pressure, for premenopausal women, flibanserin and bremelanotide can be tried, while ospemifene and hormone supplements are preferred for postmenopausal women.

Safety Profile of Bremelanotide Across the Clinical Development Program

Background: Bremelanotide, a melanocortin receptor agonist, is Food and Drug Administration (FDA)-approved for the treatment of premenopausal women with acquired, generalized hypoactive sexual desire disorder. Methods: Review of bremelanotide's safety profile from the clinical development program (phases 1 through 3). Results: The clinical development program comprised 3500 subjects in 43 completed studies. In the phase 3 studies, subjects took bremelanotide for up to 18 months. The most common adverse events (AEs) were nausea (40.0% vs. 1.3%), flushing (20.3% vs. 1.3%), headache (11.3% vs. 1.9%), and injection site reactions (5.4 vs. 0.5), bremelanotide versus placebo groups, respectively, in the integrated double-blind portion of the phase 3 studies (N = 1247). Nausea was the most common reason for bremelanotide discontinuation. There were no deaths; a few subjects experienced serious AEs. Focal hyperpigmentation was rare when bremelanotide was dosed in accordance with label recommendations, but it occurred in more than one-third of subjects following up to 16 consecutive daily dosings. Small and transient but statistically significant blood pressure increases were observed during ambulatory blood pressure monitoring. Most drug-drug interactions were not clinically significant, except for interactions that lowered plasma concentrations of indomethacin and naltrexone. In the double-blind portion of the integrated phase 3 studies, 70% of the bremelanotide group proceeded to the open-label phase of the studies versus 87% of those on placebo. Conclusions: The AEs associated with bremelanotide are mostly mild to moderate. Although not deemed clinically important, bremelanotide should be used with caution in patients at risk of cardiovascular disease, and blood pressure should be well controlled during treatment. Clinical Trial Registration number: NCT02333071 [Study 301] and NCT02338960 [Study 302].

Bremelanotide for Treatment of Female Hypoactive Sexual Desire

Hypoactive sexual desire disorder (HSDD) is a persistent deficiency or absence of sexual fantasies and desire resulting in significant distress or interpersonal difficulty. Women with this disorder may display a lack of motivation for sexual activity, reduced responsiveness to erotic cues, a loss of interest during sexual activity, and avoidance of situations that could lead to sexual activity. The pathophysiology of HSDD is thought to be centered around inhibitory and excitatory hormones, neurotransmitters, and specific brain anatomy. Due to the multifactorial nature of HSDD, treatment can be complex and must attempt to target the biological and psychosocial aspects of the disorder. Bremelanotide is a melanocortin receptor agonist and has been recently approved by the FDA to treat HSDD. Bremelanotide is administered intranasally or as a subcutaneous injection. The recommended dosage of bremelanotide is 1.75 mg injected subcutaneously in the abdomen or thigh at least 45 min before sexual activity. Studies showed improvements in desire, arousal, and orgasm scores when 1.75 mg of bremelanotide was administered before sexual activity compared to a placebo. Bremelanotide is a promising way to treat HSDD.

Re-Analyzing Phase III Bremelanotide Trials for "Hypoactive Sexual Desire Disorder" in Women

Kingsberg et al. described results from two 24-week Phase III trials of bremelanotide for treating hypoactive sexual desire disorder (HSDD) in women. 72.72% of protocol-listed outcomes were not reported by Kingsberg et al., who provided results of 15 secondary measures which were not listed in the study protocols. None of their efficacy outcomes were reported in line with CONSORT data reporting standards and no secondary outcome had a stated rationale or cited evidence of validity. My meta-analysis of the trials' data, based on the FDA New Drug Application, found similar results to Kingsberg et al. However, Kingsberg et al. did not report that a) adverse event-induced study discontinuation was substantially higher on bremelanotide: OR = 11.98, 95% CI = 3.74-38.37, NNH: 6 or b) participants preferred placebo, measured by the combination of both 1) completing a clinical trial and 2) electing to participate in the follow-up open-label study (OR = 0.30, 95% CI = .24-.38, NNH: 4). Bremelanotide's modest benefits on incompletely reported post-hoc measures of questionable validity in combination with participants substantially preferring to take placebo suggest that the drug is generally not useful. Kingsberg et al.'s data reporting and measurement practices were incomplete and lacked transparency.

Psychometric validation of the Female Sexual Distress Scale-Desire/Arousal/Orgasm

Background

For the treatment of female sexual dysfunction, the most relevant outcome measures are patient-reported treatment effects and changes in symptoms, underscoring the need for reliable, validated patient-reported outcome (PRO) instruments. The aim of this study was to evaluate the psychometric characteristics (validity and reliability) of the Female Sexual Distress Scale-Desire/Arousal/Orgasm (FSDS-DAO) PRO measure, which was adapted from the validated FSDS-Revised (FSDS-R) questionnaire and added 2 questions involving arousal and orgasm.

Methods

Psychometric analyses were based on the data from a multicenter phase 2b dose-finding study that compared the safety and efficacy of bremelanotide versus placebo and were conducted in the evaluable modified intent-to-treat population (N = 325) from that study. Psychometric evaluation of the new items in the FSDS-DAO included confirmatory factor analyses, tests of internal consistency and test–retest reliability, examinations of convergent and discriminant validity, and determination of responsiveness. The validity of the FSDS-DAO was evaluated based on previously developed instruments, including the Female Sexual Function Index (FSFI), General Assessment Questionnaire (GAQ), Women’s Inventory of Treatment Satisfaction (WITS-9), and Female Sexual Encounter Profile-Revised (FSEP-R).

Results

Confirmatory factor analyses demonstrated that the FSDS-DAO items fit very well (Bentler’s comparative fit index of 0.929). Cronbach’s α for the FSDS-DAO total score was ≥ 0.91 at Visits 1, 2, 5, and 12, demonstrating adequate internal consistency reliability. Test–retest reliability was acceptable with an intra-class coefficient of 0.61 and a Spearman’s correlation coefficient score of 0.62 between Visits 1 and 2 (4 weeks). Acceptable construct validity was demonstrated by significant correlations with related PRO scales in the expected directions and magnitude. For example, participants reporting the worst levels of sexual function on the FSFI also showed the worst FSDS-DAO scores at Visits 5 and 12. The FSDS-DAO total score was responsive to change.

Conclusions

Evidence supports the validity and reliability of the FSDS-DAO for assessing sexually related distress in women with female sexual arousal disorder and/or hypoactive sexual desire disorder; the addition of the arousal and orgasm items did not impact the validity and reliability of the measure.

Clinical Trial Registration ClinicalTrials.gov NCT01382719.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41687-021-00359-1.

A Systematic Literature Review of Health-related Quality of Life Measures for Women with Hypoactive Sexual Desire Disorder and Female Sexual Interest/Arousal Disorder

INTRODUCTION

Hypoactive Sexual Desire Disorder (HSDD) / Female Sexual Interest/Arousal Disorder (FSIAD) impacts health-related quality of life (HRQoL) of women and their partners, yet existing measures fail to adequately capture relevant concepts (ie, what is essential to measure including symptoms/impacts) important to women with HSDD/FSIAD.

OBJECTIVES

To identify HRQoL tools used to assess women with HSDD/FSIAD, and to evaluate their psychometric properties (ie, reliability, validity, and responsiveness).

METHODS

We conducted searches in PubMed, Embase and PsychINFO from June 5, 1989 to September 30, 2020 for studies in women with HSDD/FSIAD and psychometric analyses (English only). Principles of the Preferred Reporting Items for Systematic reviews and Meta-Analyses, the COnsensus-based Standards for the selection of health Measurement INstruments Risk of Bias Checklist and other psychometric criteria were applied. Based on this search, 56 papers were evaluated including 15 randomized-controlled trials, 11 observational/single arm/open label studies, and 30 psychometric studies.

RESULTS

Of the 18 measures identified, the Female Sexual Function Index (FSFI) and Female Sexual Distress Scale-Revised (FSDS-R) were included in most studies (> 50%). General HRQoL instruments were not used in any of the clinical trials; the SF-12, SF-36 and EQ-5D-5L were reported in two observational studies. No instruments achieved positive quality ratings across all psychometric criteria. The FSFI, FSDS-R, Sexual Event Diary (SED) and the Sexual Desire Relationship Distress Scale (SDRDS), were the only measures to receive a positive rating for content validity.

CONCLUSION

Reliable and valid HRQoL measures that include sexual desire and distress are needed to provide a more systematic and comprehensive assessment of HRQoL and treatment benefits in women with HSDD/FSIAD. While inferences about HRQoL are limited due to the lack of uniformity in concepts assessed and limited psychometric evaluation of these measures in women with HSDD/FSIAD, opportunities exist for the development of reliable and validated tools that comprehensively measure the most relevant and important concepts in women with HSDD/FSIAD. Lim-Watson MZ, Hays RD, Kingsberg S, et al. A systematic literature review of health-related quality of life measures for women with Hypoactive Sexual Desire Disorder and Female Sexual Interest/Arousal Disorder. Sex Med Rev 2021;XX:XXX-XXX.

The melanocortin pathway and energy homeostasis: From discovery to obesity therapy

Background

Over the past 20 years, insights from human and mouse genetics have illuminated the central role of the brain leptin-melanocortin pathway in controlling mammalian food intake, with genetic disruption resulting in extreme obesity, and more subtle polymorphic variations influencing the population distribution of body weight. At the end of 2020, the U.S. Food and Drug Administration (FDA) approved setmelanotide, a melanocortin 4 receptor agonist, for use in individuals with severe obesity due to either pro-opiomelanocortin (POMC), proprotein convertase subtilisin/kexin type 1 (PCSK1), or leptin receptor (LEPR) deficiency.

Scope of review

Herein, we chart the melanocortin pathway's history, explore its pharmacology, genetics, and physiology, and describe how a neuropeptidergic circuit became an important druggable obesity target.

Major conclusions

Unravelling the genetics of the subset of severe obesity has revealed the importance of the melanocortin pathway in appetitive control; coupling this with studying the molecular pharmacology of compounds that bind melanocortin receptors has brought a new obesity drug to the market. This process provides a drug discovery template for complex disorders, which for setmelanotide took 25 years to transform from a single gene into an approved drug.

The Menopause Transition: Signs, Symptoms, and Management Options

CONTEXT

Menopause, the permanent cessation of menses, reflects oocyte depletion and loss of gonadal steroids. It is preceded by a transition state, the perimenopause, which is characterized by the gradual loss of oocytes, altered responsiveness to gonadal steroid feedback, wide hormonal fluctuations, and irregular menstrual patterns. The goal of this mini-review is to discuss the basic pathophysiology of the menopausal transition and the hormonal and nonhormonal management of clinicopathology attributed to it.

EVIDENCE ACQUISITION

A Medline search of epidemiologic, population-based studies, and studies of reproductive physiology was conducted. A total of 758 publications were screened.

EVIDENCE SYNTHESIS

The reproductive hormonal milieu of the menopausal transition precipitates bothersome vasomotor symptoms, mood disruption, temporary cognitive dysfunction, genitourinary symptoms, and other disease processes that reduce the quality of life of affected women. The endocrine tumult of the menopause transition also exposes racial and socioeconomic disparities in the onset, severity, and frequency of symptoms. Hormone therapy (HT) treatment can be effective for perimenopausal symptoms but its use has been stymied by concerns about health risks observed in postmenopausal HT users who are older than 60 and/or women who have been postmenopausal for greater than 10 years.

CONCLUSIONS

The menopause transition is a disruptive process that can last for over a decade and causes symptoms in a majority of women. It is important for clinicians to recognize early signs and symptoms of the transition and be prepared to offer treatment to mitigate these symptoms. Many safe and effective options, including HT, are available.

Reliability and validity of the elements of desire questionnaire in premenopausal women with hypoactive sexual desire disorder

Background

The Elements of Desire Questionnaire (EDQ) is a patient-reported outcome (PRO) measure developed to evaluate sexual desire and was included in two identically designed phase 3 clinical trials (RECONNECT) as an exploratory endpoint. The EDQ was developed based on a literature review, qualitative research with patients with hypoactive sexual desire disorder (HSDD), and input from clinical experts. This instrument is intended to be used to collect efficacy data in clinical trials evaluating potential treatments for HSDD. The objective of this study was to evaluate the measurement properties of both the monthly and daily recall versions of the EDQ during the RECONNECT trials.

Methods

Participants completed the EDQ daily version for 7 consecutive days prior to selected monthly clinic visits. The monthly recall version was completed at each monthly clinic visit. The analysis population consisted of all subjects with Female Sexual Function Index (FSFI) data at baseline and ≥ 1 follow-up visit.

Results

At baseline, 1144 and 676 subjects completed the monthly and daily recall EDQs, respectively. The EDQ scores had good internal consistency and test-retest reliability. Monthly and daily recall EDQ scores were correlated with FSFI-desire domain scores at baseline and month 3. Scores from the monthly and daily recall versions were also correlated. After 6 months, there was a significantly greater improvement for bremelanotide versus placebo in both the monthly and daily recall versions (both P < 0.0001).

Conclusions

The results demonstrated that EDQ exhibited good reliability, validity, and sensitivity to change. Consistent with other validated PRO measures of sexual desire, the EDQ provides additional insights into sexual desire.

Trial registration

NCT02338960 and NCT02333071 (RECONNECT studies).

Topical Alpha-1 Adrenergic Receptor Agonist Applied to the Nipple/Areola Complex Improves Female Orgasmic Function

Background: The impact of nipple sensation and its relationship to sexual function have often been neglected in medical literature. However, several recent studies report the importance of the nipple/areola complex (NAC) in sexual arousal and overall function. The nipple is composed of smooth muscle that can be erected via adrenergic nerves. In two complementary studies, we demonstrate that stimulation of the alpha-1 adrenergic receptor in the NAC with topical adrenergic agents can initiate erection of the nipple, increase NAC sensitivity, and improve sexual function. Materials and Methods: Thirteen breast surgery patients with nipple sensitivity loss were recruited to an unblinded study of topical phenylephrine hydrochloride. Sensitivity to pressure was measured before and after the application of the intervention to the NAC. In a second pilot study, 35 women completed a double-blinded placebo-controlled trial of a novel formulation, RJ101, containing a norepinephrine releasing agent. The intervention or placebo was applied to the NAC 30 minutes before sexual activity over the 4-week trial period. The arousal, lubrication, and orgasm domains of the female sexual function index (FSFI) were used to measure sexual function. Results: The application of phenylephrine hydrochloride was shown to increase nipple sensitivity to pressure by an average of 20% in our cohort of 13 breast augmentation patients. In addition, it was shown that intermittent application of the alpha-1 agonist for 8 weeks increased basal NAC sensitivity. In the follow-up pilot study, we demonstrate that stimulation of the NAC with RJ101 produced statistically significant increases versus placebo in the lubrication and orgasm domains of the FSFI, p = 0.0226 and p = 0.0269, respectively. Conclusion: For the first time, we demonstrate that the application of a topical alpha-1 adrenergic receptor agonist or a norepinephrine-releasing agent increases the sensitivity of the NAC and subsequently significantly improves sexual function.

Melanocortin 3 receptor activation with [D-Trp8]-γ-MSH suppresses inflammation in apolipoprotein E deficient mice

The melanocortin MC₁ and MC₃ receptors elicit anti-inflammatory actions in leukocytes and activation of these receptors has been shown to alleviate arterial inflammation in experimental atherosclerosis. Thus, we aimed to investigate whether selective targeting of melanocortin MC₃ receptor protects against atherosclerosis. Apolipoprotein E deficient (ApoE^-/-) mice were fed high-fat diet for 12 weeks and randomly assigned to receive either vehicle (n = 11) or the selective melanocortin MC₃ receptor agonist [D-Trp(8)]-gamma-melanocyte-stimulating hormone ([D-Trp8]-γ-MSH; 15 μg/day, n = 10) for the last 4 weeks. Lesion size as well as macrophage and collagen content in the aortic root plaques were determined. Furthermore, leukocyte counts in the blood and aorta and cytokine mRNA expression levels in the spleen, liver and aorta were quantified. No effect was observed in the body weight development or plasma cholesterol level between the two treatment groups. However, [D-Trp8]-γ-MSH treatment significantly reduced plasma levels of chemokine (C-C motif) ligands 2, 4 and 5. Likewise, cytokine and adhesion molecule expression levels were reduced in the spleen and liver of γ-MSH-treated mice, but not substantially in the aorta. In line with these findings, [D-Trp8]-γ-MSH treatment reduced leukocyte counts in the blood and aorta. Despite reduced inflammation, [D-Trp8]-γ-MSH did not change lesion size, macrophage content or collagen deposition of aortic root plaques. In conclusion, the findings indicate that selective activation of melanocortin MC₃ receptor by [D-Trp8]-γ-MSH suppresses systemic and local inflammation and thereby also limits leukocyte accumulation in the aorta. However, the treatment was ineffective in reducing atherosclerotic plaque size.

Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials

Bremelanotide significantly improves sexual desire and related distress in premenopausal women with hypoactive sexual distress disorder and has a favorable safety profile.

To evaluate the safety and efficacy of bremelanotide for the treatment of premenopausal women with hypoactive sexual desire disorder.

Long-Term Safety and Efficacy of Bremelanotide for Hypoactive Sexual Desire Disorder

The 52-week open-label extension of the RECONNECT studies demonstrates bremelanotide's favorable safety profile, with sustained efficacy in treating hypoactive sexual desire disorder in premenopausal women.

To evaluate the long-term safety and efficacy of bremelanotide as treatment for hypoactive sexual desire disorder in premenopausal women.

Bremelanotide: First Approval

Bremelanotide (Vyleesi™) is a melanocortin receptor agonist recently approved in the USA for the treatment of premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD), as characterized by low sexual desire that causes marked distress or interpersonal difficulty. It is a self-administered, on-demand subcutaneous therapy. Initially developed by Palatin Technologies who sponsored the Phase 3 clinical trials, bremelanotide was subsequently out-licensed to AMAG Pharmaceuticals Inc. for exclusive North American rights to develop and commercialize the drug, including submitting the New Drug Application to the US FDA. Bremelanotide is a synthetic peptide analogue of the neuropeptide hormone alpha melanocyte-stimulating hormone (α-MSH) with high affinity for the melanocortin type 4 receptor (thought to be important for sexual function), giving it the potential to modulate brain pathways involved in sexual response. This article summarizes the milestones in the development of bremelanotide leading to this first regulatory approval.

Bremelanotide: New Drug Approved for Treating Hypoactive Sexual Desire Disorder

Objective: To review data regarding bremelanotide, a recently approved therapy for hypoactive sexual desire disorder (HSDD). Data Sources: Literature search of Medline, SCOPUS, and EMBASE was performed using the search terms bremelanotide, bremelanotide injection, Vyleesi, and melanocortin 4 receptor agonist between January 1, 1996, and December 15, 2019. Reference lists from included articles were also reviewed for pertinent citations. Study Selection/Data Extraction: We included phase 2 and 3 trials of bremelanotide. There were 2 reports of phase 3 trials and 2 reports of phase 2 trials. Additional information from supplementary analyses was also referenced. Data Synthesis: Bremelanotide demonstrates significant improvement in desire and a significant decrease in distress related to lack of desire. The most common adverse effects include nausea (39.9%), facial flushing (20.4%), and headache (11%). Relevance to Patient Care and Clinical Practice: Bremelanotide is the second Food and Drug Administration–approved medication for the treatment of HSDD. Bremelanotide’s place in therapy is unknown, as the HSDD guidelines were last updated in 2017. Although the trials met statistical significance for change in sexual desire elements and distress related to sexual desire, the clinical benefit may only be modest. Conclusion: Bremelanotide is a subcutaneous injection that can be administered as needed approximately 45 minutes prior to sexual activity. Bremelanotide is safe and has limited drug-drug interactions, including no clinically significant interactions with ethanol. Prescribing guidelines recommend no more than 1 dose in 24 hours and no more than 8 doses per month. Individuals should discontinue use after 8 weeks without benefit.

Female Sexual Dysfunction and the Placebo Effect: A Meta-analysis

OBJECTIVE

To quantify the placebo effect of various pharmacologic modalities including neuromodulators, hormonal agents, and onabotulinum toxin A for female sexual dysfunction.

DATA SOURCES

Using Meta-analyses Of Observational Studies in Epidemiology guidelines, we conducted a systematic review of PubMed, EMBASE, ClinicalTrials.gov, and the Cochrane Review databases.

METHODS OF STUDY SELECTION

Eleven search terms, "female sexual dysfunction" "treatment" in combination with "hypoactive sexual desire," "arousal disorder," "sexual pain disorder," "genitourinary syndrome of menopause," "orgasmic disorder," "vulvovaginal atrophy," "vaginismus," "vaginal atrophy," "vulvodynia," and "vestibulitis," were used. Studies were included if their design was randomized, included a placebo arm, and used the Female Sexual Function Index as an outcome measure.

TABULATION, INTEGRATION, AND RESULTS

The placebo effect on the Female Sexual Function Index was compared with each respective study's treatment effect using inverse-variance weighting in a random-effects analysis model. Six hundred five relevant articles were retrieved. Twenty-four randomized controlled trials included a placebo arm. Of these, eight studies used the Female Sexual Function Index. Across these studies, 1,723 women with clinical pretreatment female sexual dysfunction received placebo. Two thousand two hundred thirty-six women were in the treatment arm of the respective studies and received various pharmacologic interventions including flibanserin, bupropion, onabotulinum toxin A, intravaginal prasterone, intranasal oxytocin, ospemifene, and bremelanotide. Women receiving placebo improved 3.62 (95% CI 3.29-3.94) on the Female Sexual Function Index. The treatment arm had a corresponding increase of 5.35 (95% CI 4.13-6.57).

CONCLUSION

This meta-analysis of Level I evidence demonstrates that 67.7% of the treatment effect for female sexual dysfunction is accounted for by placebo. Our findings suggest that the current treatments for female sexual dysfunction are, overall, minimally superior to placebo, which emphasizes the ongoing need for more efficacious treatment for female sexual dysfunction.

Sexual Health in Menopause

Sexual function worsens with advancing menopause status. The most frequently reported symptoms include low sexual desire (40–55%), poor lubrication (25–30%) and dyspareunia (12–45%), one of the complications of genitourinary syndrome of menopause (GSM). Declining levels of sex steroids (estrogens and androgens) play a major role in the impairment of sexual response; however, psychological and relational changes related with aging and an increase in metabolic and cardiovascular comorbidities should also be taken into account. Although first-line therapeutic strategies for menopause-related sexual dysfunction aim at addressing modifiable factors, many hormonal and non-hormonal, local and systemic treatment options are currently available. Treatment should be individualized, taking into account the severity of symptoms, potential adverse effects and personal preferences.

Multilevel analyses of on-demand medication data, with an application to the treatment of Female Sexual Interest/Arousal Disorder

Data from clinical trials investigating on-demand medication often consist of an intentionally varying number of measurements per patient. These measurements are often observations of discrete events of when the medication was taken, including for example data on symptom severity. In addition to the varying number of observations between patients, the data have another important feature: they are characterized by a hierarchical structure in which the events are nested within patients. Traditionally, the observed events of patients are aggregated into means and subsequently analyzed using, for example, a repeated measures ANOVA. This procedure has drawbacks. One drawback is that these patient means have different standard errors, first, because the variance of the underlying events differs between patients and second, because the number of events per patient differs. In this paper, we argue that such data should be analyzed by applying a multilevel analysis using the individual observed events as separate nested observations. Such a multilevel approach handles this drawback and it also enables the examination of varying drug effects across patients by estimating random effects. We show how multilevel analyses can be applied to on-demand medication data from a clinical trial investigating the efficacy of a drug for women with low sexual desire. We also explore linear and quadratic time effects that can only be performed when the individual events are considered as separate observations and we discuss several important statistical topics relevant for multilevel modeling. Taken together, the use of a multilevel approach considering events as nested observations in these types of data is advocated as it is more valid and provides more information than other (traditional) methods.

Current Mechanistic and Pharmacodynamic Understanding of Melanocortin-4 Receptor Activation

In this work we summarize our understanding of melanocortin 4 receptor (MC4R) pathway activation, aiming to define a safe and effective therapeutic targeting strategy for the MC4R. Delineation of cellular MC4R pathways has provided evidence for distinct MC4R signaling events characterized by unique receptor activation kinetics. While these studies remain narrow in scope, and have largely been explored with peptidic agonists, the results provide a possible correlation between distinct ligand groups and differential MC4R activation kinetics. In addition, when a set of small-molecule and peptide MC4R agonists are compared, evidence of biased signaling has been reported. The results of such mechanistic studies are discussed.

Expert opinion on existing and developing drugs to treat female sexual dysfunction

INTRODUCTION

Female sexual dysfunction (FSD) is a highly prevalent, yet commonly underdiagnosed and undertreated condition. This paper reviews the diagnostic terminology for FSD, and basic sexual physiology in women. The Food and Drug Administration (FDA) approved drugs for FSD are discussed, followed by investigational drugs for FSD currently in phase 2 or 3 clinical trials, reasons for failure of drug development, and potential future drug targets. Areas covered: A literature review was conducted for available treatments for FSD: flibanserin, estrogen, ospemifene and prasterone. Potential treatments are assessed, as was the Pharmaprojects database which includes clinical trial information. Testosterone, bremelanotide, bupropion-trazodone, PDE-5 inhibitors, prostaglandins, tibolone and combination therapies, and the theoretical basis of potential drug targets are discussed. Expert opinion: The lack of established endpoints for phase 3 studies of FSD has impeded approval of new treatments, and required additional studies for validation, resulting in proposed changes to the FDA draft guidance for FSD clinical trials in October 2016. Current DSM-5 diagnostic nosology also fails to capture the full range of symptomology. Several promising compounds have shown no movement for several years limiting women's options. Overcoming socio-cultural bias against women's sexual and reproductive health will be critical in the approval of new treatments for FSD.

Genetic variation in the SIM1 locus is associated with erectile dysfunction

Erectile dysfunction is a common condition of men in middle and older ages. Twin studies suggest that about one-third of the risk is due to genetic factors, independent of other known erectile dysfunction risk factors. However, studies that have searched for specific genetic contributors have been limited due to small sample sizes, candidate gene approaches, and weak phenotyping. As a result, there are no confirmed genetic risk factors for erectile dysfunction. This study finds a specific genetic cause for erectile dysfunction.

Erectile dysfunction affects millions of men worldwide. Twin studies support the role of genetic risk factors underlying erectile dysfunction, but no specific genetic variants have been identified. We conducted a large-scale genome-wide association study of erectile dysfunction in 36,649 men in the multiethnic Kaiser Permanente Northern California Genetic Epidemiology Research in Adult Health and Aging cohort. We also undertook replication analyses in 222,358 men from the UK Biobank. In the discovery cohort, we identified a single locus (rs17185536-T) on chromosome 6 near the single-minded family basic helix-loop-helix transcription factor 1 (SIM1) gene that was significantly associated with the risk of erectile dysfunction (odds ratio = 1.26, P = 3.4 × 10⁻²⁵). The association replicated in the UK Biobank sample (odds ratio = 1.25, P = 6.8 × 10⁻¹⁴), and the effect is independent of known erectile dysfunction risk factors, including body mass index (BMI). The risk locus resides on the same topologically associating domain as SIM1 and interacts with the SIM1 promoter, and the rs17185536-T risk allele showed differential enhancer activity. SIM1 is part of the leptin–melanocortin system, which has an established role in body weight homeostasis and sexual function. Because the variants associated with erectile dysfunction are not associated with differences in BMI, our findings suggest a mechanism that is specific to sexual function.

Transcutaneous Electrical Nerve Stimulation to Improve Female Sexual Dysfunction Symptoms: A Pilot Study

OBJECTIVES

To perform a pilot study using transcutaneous electrical nerve stimulation (TENS) on the dorsal genital nerve and the posterior tibial nerve for improving symptoms of female sexual dysfunction (FSD) in women without bladder problems. We hypothesize that this therapy will be effective at improving genital arousal deficits.

MATERIALS AND METHODS

Nine women with general FSD completed the study. Subjects received 12 sessions of transcutaneous dorsal genital nerve stimulation (DGNS; n = 6) or posterior tibial nerve stimulation (PTNS; n = 3). Stimulation was delivered for 30 min at 20 Hz. Sexual functioning was evaluated with the female sexual functioning index (FSFI), and surveys were also given on general health, urological functioning, and the Patients' Global Impression of Change (PGIC) after treatment. Surveys were given before treatment (baseline), after 6 and 12 weeks of treatment, and 6 weeks after the completion of stimulation sessions.

RESULTS

The average total FSFI score across all subjects significantly increased from 15.3 ± 4.8 at baseline to 20.3 ± 7.8 after six sessions, 21.7 ± 7.5 after 12 sessions, and 21.3 ± 7.1 at study completion (p < 0.05 for all time points). Increases were observed in both DGNS and PTNS subjects. Significant FSFI increases were seen in the subdomains of lubrication, arousal, and orgasm, each of which is related to genital arousal. Bladder and general health surveys did not change across the study. PGIC had a significant increase.

CONCLUSIONS

This study provides evidence that transcutaneous stimulation of peripheral nerves has the potential to be a valuable therapeutic tool for women with FSD.

Developing a Biased Unmatched Bivalent Ligand (BUmBL) Design Strategy to Target the GPCR Homodimer Allosteric Signaling (cAMP over β-Arrestin 2 Recruitment) Within the Melanocortin Receptors

Understanding the functional relevance of G protein-coupled receptor (GPCR) homodimerization has been limited by the insufficient tools to assess asymmetric signaling occurring within dimers comprised of the same receptor type. We present unmatched bivalent ligands (UmBLs) to study the asymmetric function of melanocortin homodimers. UmBLs contain one agonist and one antagonist pharmacophore designed to target a melanocortin homodimer such that one receptor is occupied by an agonist and the other receptor by an antagonist pharmacophore. First-in-class biased UmBLs (BUmBLs) targeting the human melanocortin-4 receptor (hMC4R) were discovered. The BUmBLs displayed biased agonism by potently stimulating cAMP signaling (EC₅₀ ∼ 2-6 nM) but minimally activating the β-arrestin recruitment pathway (≤55% maximum signal at 10 μM). To our knowledge, we report the first single-compound strategy to pharmacologically target melanocortin receptor allosteric signaling that occurs between homodimers that can be applied straightforwardly in vitro and in vivo to other GPCR systems.

The International Society for the Study of Women's Sexual Health Process of Care for Management of Hypoactive Sexual Desire Disorder in Women

The International Society for the Study of Women's Sexual Health process of care (POC) for management of hypoactive sexual desire disorder (HSDD) algorithm was developed to provide evidence-based guidelines for diagnosis and treatment of HSDD in women by health care professionals. Affecting 10% of adult females, HSDD is associated with negative emotional and psychological states and medical conditions including depression. The algorithm was developed using a modified Delphi method to reach consensus among the 17 international panelists representing multiple disciplines. The POC starts with the health care professional asking about sexual concerns, focusing on issues related to low sexual desire/interest. Diagnosis includes distinguishing between generalized acquired HSDD and other forms of low sexual interest. Biopsychosocial assessment of potentially modifiable factors facilitates initiation of treatment with education, modification of potentially modifiable factors, and, if needed, additional therapeutic intervention: sex therapy, central nervous system agents, and hormonal therapy, guided in part by menopausal status. Sex therapy includes behavior therapy, cognitive behavior therapy, and mindfulness. The only central nervous system agent currently approved by the US Food and Drug Administration (FDA) for HSDD is flibanserin in premenopausal women; use of flibanserin in postmenopausal women with HSDD is supported by data but is not FDA approved. Hormonal therapy includes off-label use of testosterone in postmenopausal women with HSDD, which is supported by data but not FDA approved. The POC incorporates monitoring the progress of therapy. In conclusion, the International Society for the Study of Women's Sexual Health POC for the management of women with HSDD provides a rational, evidence-based guideline for health care professionals to manage patients with appropriate assessments and individualized treatments.

Effect Size in Efficacy Trials of Women With Decreased Sexual Desire

BACKGROUND

Regarding hypoactive sexual desire disorder (HSDD) in women, some reviewers judge the effect size small for medications vs placebo, but substantial for cognitive behavior therapy (CBT) or mindfulness meditation training (MMT) vs wait list. However, we lack comparisons of the effect sizes for the active intervention itself, for the control treatment, and for the differential between the two.

AIM

For efficacy trials of HSDD in women, compare effect sizes for medications (testosterone/testosterone transdermal system, flibanserin, and bremelanotide) and placebo vs effect sizes for psychotherapy and wait-list control.

METHODS

We conducted a literature search for mean changes and SD on main measures of sexual desire and associated distress in trials of medications, CBT, or MMT. Effect size was used as it measures the magnitude of the intervention without confounding by sample size.

OUTCOMES

Cohen d was used to determine effect sizes.

RESULTS

For medications, mean (SD) effect size was 1.0 (0.34); for CBT and MMT, 1.0 (0.36); for placebo, 0.55 (0.16); and for wait list, 0.05 (0.26).

CLINICAL TRANSLATION

Recommendations of psychotherapy over medication for treatment of HSDD are premature and not supported by data on effect sizes. Active participation in treatment conveys considerable non-specific benefits. Caregivers should attend to biological and psychosocial elements, and patient preference, to optimize response.

CONCLUSIONS

Few clinical trials of psychotherapies were substantial in size or utilized adequate control paradigms. Medications and psychotherapies had similar, large effect sizes. Effect size of placebo was moderate. Effect size of wait-list control was very small, about one quarter that of placebo. Thus, a substantial non-specific therapeutic effect is associated with receiving placebo plus active care and evaluation. The difference in effect size between placebo and wait-list controls distorts the value of the subtraction of effect of the control paradigms to estimate intervention effectiveness. Pyke RE, Clayton AH. Effect Size in Efficacy Trials of Women With Decreased Sexual Desire. Sex Med Rev 2018;6:358-366.

Evaluation and Management of Hypoactive Sexual Desire Disorder

INTRODUCTION

Hypoactive sexual desire disorder (HSDD) often has a negative impact on the health and quality of life of women; however, many women do not mention-let alone discuss-this issue with their physicians. Providers of gynecologic services have the opportunity to address this subject with their patients.

AIM

To review the diagnosis and evidence-based treatment of low sexual desire in women with a focus on strategies that can be used efficiently and effectively in the clinic.

METHODS

The Medline database was searched for clinically relevant publications on the diagnosis and management of HSDD.

RESULTS

HSDD screening can be accomplished during an office visit with a few brief questions to determine whether further evaluation is warranted. Because women's sexual desire encompasses biological, psychological, social, and contextual components, a biopsychosocial approach to evaluating and treating patients with HSDD is recommended. Although individualized treatment plan development for patients requires independent medical judgment, a simple algorithm can assist in the screening, diagnosis, and management of HSDD. Once a diagnosis of HSDD has been made, interventions can begin with office-based counseling and progress to psychotherapy and/or pharmacotherapy. Flibanserin, a postsynaptic 5-hydroxytryptamine 1A agonist and 2A antagonist that decreases serotonin levels and increases dopamine and norepinephrine levels, is indicated for acquired, generalized HSDD in premenopausal women and is the only agent approved in the United States for the treatment of HSDD in women. Other strategies to treat HSDD include using medications indicated for other conditions (eg, transdermal testosterone, bupropion). Bremelanotide, a melanocortin receptor agonist, is in late-stage clinical development.

CONCLUSIONS

Providers of gynecologic care are uniquely positioned to screen, counsel, and refer patients with HSDD. Options for pharmacotherapy of HSDD are currently limited to flibanserin, approved by the US Food and Drug Administration, and off-label use of other agents. Clayton AH, Kingsberg SA, Goldstein I. Evaluation and Management of Hypoactive Sexual Desire Disorder. Sex Med 2018;6:59-74.

MC4R Agonists: Structural Overview on Antiobesity Therapeutics

The melanocortin-4 receptor (MC4R) regulates adipose tissue formation and energy homeostasis, and is believed to be a monogenic target for novel antiobesity therapeutics. Several research efforts targeting this receptor have identified potent and selective agonists. While viable agonists have been characterized in vitro, undesirable side effects frequently appeared during clinical trials. The most promising candidates have diverse structures, including linear peptides, cyclic peptides, and small molecules. Herein, we present a compilation of potent MC4R agonists and discuss the pivotal structural differences within those molecules that resulted in good selectivity for MC4R over other melanocortins. We provide insight on recent progress in the field and reflect on directions for development of new agonists.

Understanding the Role of Serotonin in Female Hypoactive Sexual Desire Disorder and Treatment Options

BACKGROUND

The neurobiology of sexual response is driven in part by dopamine and serotonin-the former modulating excitatory pathways and the latter regulating inhibitory pathways. Neurobiological underpinnings of hypoactive sexual desire disorder (HSDD) are seemingly related to overactive serotonin activity that results in underactive dopamine activity. As such, pharmacologic agents that decrease serotonin, increase dopamine, or some combination thereof, have therapeutic potential for HSDD.

AIM

To review the role of serotonin in female sexual function and the effects of pharmacologic interventions that target the serotonin system in the treatment of HSDD.

METHODS

Searches of the Medline database for articles on serotonin and female sexual function.

OUTCOMES

Relevant articles from the peer-reviewed literature were included.

RESULTS

Female sexual response is regulated not only by the sex hormones but also by several neurotransmitters. It is postulated that dopamine, norepinephrine, oxytocin, and melanocortins serve as key neuromodulators for the excitatory pathways, whereas serotonin, opioids, and endocannabinoids serve as key neuromodulators for the inhibitory pathways. Serotonin appears to be a key inhibitory modulator of sexual desire, because it decreases the ability of excitatory systems to be activated by sexual cues. Centrally acting drugs that modulate the excitatory and inhibitory pathways involved in sexual desire (eg, bremelanotide, bupropion, buspirone, flibanserin) have been investigated as treatment options for HSDD. However, only flibanserin, a multifunctional serotonin agonist and antagonist (5-hydroxytryptamine [5-HT]_1A receptor agonist and 5-HT_2A receptor antagonist), is currently approved for the treatment of HSDD.

CLINICAL IMPLICATIONS

The central serotonin system is 1 biochemical target for medications intended to treat HSDD.

STRENGTHS AND LIMITATIONS

This narrative review integrates findings from preclinical studies and clinical trials to elucidate neurobiological underpinnings of HSDD but is limited to 1 neurotransmitter system (serotonin).

CONCLUSION

Serotonin overactivity is a putative cause of sexual dysfunction in patients with HSDD. The unique pharmacologic profile of flibanserin tones down inhibitory serotonergic function and restores dopaminergic and noradrenergic function. Croft HA. Understanding the Role of Serotonin in Female Hypoactive Sexual Desire Disorder and Treatment Options. J Sex Med 2017;14:1575-1584.

Sexual Function Post-Breast Cancer

The consequences of estrogen deprivation and therapeutic interventions such as radiation, chemotherapy and surgery have a significant negative impact on libido, sexual arousal, orgasmic function and the ability to have pleasurable intercourse. Evaluation and treatment of female sexual dysfunction is a significant unmet need in the breast cancer survivor in spite of the availability of safe and effective treatments.

Recent Developments in Psychopharmaceutical Approaches to Treating Female Sexual Interest and Arousal Disorder

Purpose of Review

This review summarizes the recent literature and empirical studies on psychopharmacological approaches to treating female sexual interest/arousal disorder (FSIAD).

Recent Findings

Several new drugs for FSIAD that are intended to increase sexual responsiveness by influencing central excitatory and inhibitory neuromodulatory processes are under development. Studies on flibanserin resulted in the first approved medication for the treatment of low sexual desire in premenopausal women. New drugs under development are testosterone combined with sildenafil or buspiron, bremelanotide, BP101, and nasal testosterone (TBS-2).

Summary

Although pharmacological enhancement of sexual responsiveness may be potentially helpful in the treatment of FSIAD, the observed effects of flibanserin and other new drugs under development seem limited in terms of clinical significance. Given the multifactorial character of FSIAD, it may be important to integrate psychopharmacological treatment with sex therapy for optimal treatment efficacy.