Targeting the central melanocortin system for the treatment of metabolic disorders.

A large body of preclinical and clinical data shows that the central melanocortin system is a promising therapeutic target for treating various metabolic disorders such as obesity and cachexia, as well as anorexia nervosa. Setmelanotide, which functions by engaging the central melanocortin circuitry, was approved by the FDA in 2020 for use in certain forms of syndromic obesity. Furthermore, the FDA approvals in 2019 of two peptide drugs targeting melanocortin receptors for the treatment of generalized hypoactive sexual desire disorder (bremelanotide) and erythropoietic protoporphyria-associated phototoxicity (afamelanotide) demonstrate the safety of this class of peptides. These approvals have also renewed excitement in the development of therapeutics targeting the melanocortin system. Here, we review the anatomy and function of the melanocortin system, discuss progress and challenges in developing melanocortin receptor-based therapeutics, and outline potential metabolic and behavioural disorders that could be addressed using pharmacological agents targeting these receptors.

Preparation and In Vitro and In Vivo Evaluation of a Testosterone Film Forming Gel for the Treatment of Hypoactive Sexual Desire Disorder in Women.

Hypoactive sexual desire disorder (HSDD) is one of the most common sexual complaints in women. Currently, there is an unmet need for a drug treatment for this disorder. The purpose of this study was to develop a testosterone (TS) film forming gel used for women to treat HSDD by measuring the tackiness, peel adhesion force, tensile strength, and elasticity of the formulation. Diethylene glycol monoethyl ether (Transcutol P), an efficient penetration enhancer, was added to the optimized formulation and the transdermal permeation characteristics in vitro were studied using Franz-diffusion cells. The quantitative determination of TS was performed by high-performance liquid chromatography (HPLC). After 24 h, Transcutol P at 3% had the largest cumulative amount of drug and enhancement ratio of TS of 75.14 µg/cm2 and 2.82, respectively. After the screening of film forming polymers and penetration enhancers, the optimal formulation was as follows: glycerol (1%, w/w); 12.5% sodium carboxymethylcellulose (CMC-Na) aqueous solution (0.5%, w/w); 2.5% Carbomer ethanol solution (0.5%, w/w); Transcutol P ethanol solution (3%, w/w) containing 0.5% TS; and 8% Poly vinyl alcohol (PVA) aqueous solution (30%, w/w). The optimized film forming gel had good uniformity and the release of TS in vitro was close to 100% within 24 h. In vivo studies showed the formulations had optimal area under blood drug concentration curve values in the order of 3% Transcutol P > 1% Transcutol P > 5% Transcutol P > control preparation. The formulation with 3% Transcutol P provided the highest permeation effect both in vitro and in vivo. The safety of this formulation was further evaluated with a skin irritation test. It could effectively improve the rabbit skin irritation observed with a marketed transdermal patch Androderm®. The present study provides a promising approach for the development of a novel TS film forming gel for the treatment of HSDD in women.

Global Consensus Position Statement on the Use of Testosterone Therapy for Women.

This Position Statement has been endorsed by the International Menopause Society, The Endocrine Society, The European Menopause and Andropause Society, The International Society for Sexual Medicine, The International Society for the Study of Women's Sexual Health, The North American Menopause Society, The Federacion Latinoamericana de Sociedades de Climaterio y Menopausia, The Royal College of Obstetricians and Gynecologists, The International Society of Endocrinology, The Endocrine Society of Australia, and The Royal Australian and New Zealand College of Obstetricians and Gynecologists.

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.

The Bio-Psycho-Social Dimension in Women's Sexual Desire: 'Argumentum ad novitatem'.

Sexual desire includes complex motivation and drive. In the context of biological and cognitive- emotive state art of science, it is often a neglected field in medicine. In regard to the treatment, study on women's sexual function received less attention compared to the men's sexuality. In the past, this endeavor was relatively not well disseminated in the scientific community. Recently, there was a revolutionized surge of drug targets available to treat women with low sexual desire. It is timely to review the relevant biological approach, especially in the context of pharmacotherapy to understand this interesting clinical entity which was modulated by numerous interactive psychosocial inter-play and factors. The complex inter-play between numerous dimensional factors lends insights to understand the neural mechanism, i.e. the rewards centre pathway and its interaction with external psychosocialstimulus, e.g. relationship or other meaningful life events. The function of hormones, e.g. oxytocin or testosterone regulation was described. The role of neurotransmitters as reflected by the introduction of a molecule of flibenserin, a full agonist of the 5-HT1A and partial agonist of the D4 to treat premenopausal women with low sexual desire was deliberated. Based on this fundamental scientific core knowledge, we suggest an outline on know-how of introduction for sex therapy (i.e. "inner-self" and "outer-self") where the role of partner is narrated. Then, we also highlighted on the use of pharmacological agent as an adjunct scope of therapy, i.e. phosphodiasterase-5 (PDE-5) inhibitors and hormonal treatment in helping the patient with low sexual desire.

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-HT2A 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.

Hormonal effect on the relationship between migraine and female sexual dysfunction.

It is not a well-established finding in migraine that female sexual dysfunction (FSD) emerging as a natural course of disease, as a result of accompanying depression/anxiety, or an underlying endocrinological abnormality. Our aim is evaluating the relationship among frequency and severity of migraine, FSD, depression, anxiety, and related hormones in migrainous women. We examined 80 migrainous female and 62 controls cross sectionally. Beck Depression and Anxiety Inventories, Female Sexual Dysfunction Inventory, Migraine Disability Assessment Test, and hormonal analysis were done. Independent risk factors were identified by logistic regression analysis and cut-off values were measured with Receiver Operating Curve. FSD was not related to frequency or severity of migraine. Although depression and anxiety was related to arousal and lubrication, they had limited effect in FSD. There were correlations between prolactin (PRL), desire and lubrication, follicular-stimulating hormone FSH and orgasm, luteinizing hormone (LH), and pain. Also FSH-LH combination and PRL were found as independent factors for FSD. FSH-LH combination and PRL were found as independent factors which had effect on FSD in migraine. Our study is a precursor study about the effect of several hormones on FSD and migraine relationship. Hormonal effect on FSD in migraine will be clearer with future studies.

Methylation of HPA axis related genes in men with hypersexual disorder.

Hypersexual Disorder (HD) defined as non-paraphilic sexual desire disorder with components of compulsivity, impulsivity and behavioral addiction, and proposed as a diagnosis in the DSM 5, shares some overlapping features with substance use disorder including common neurotransmitter systems and dysregulated hypothalamic-pituitary-adrenal (HPA) axis function. In this study, comprising 67 HD male patients and 39 male healthy volunteers, we aimed to identify HPA-axis coupled CpG-sites, in which modifications of the epigenetic profile are associated with hypersexuality. The genome-wide methylation pattern was measured in whole blood using the Illumina Infinium Methylation EPIC BeadChip, measuring the methylation state of over 850K CpG sites. Prior to analysis, the global DNA methylation pattern was pre-processed according to standard protocols and adjusted for white blood cell type heterogeneity. We included CpG sites located within 2000bp of the transcriptional start site of the following HPA-axis coupled genes: Corticotropin releasing hormone (CRH), corticotropin releasing hormone binding protein (CRHBP), corticotropin releasing hormone receptor 1 (CRHR1), corticotropin releasing hormone receptor 2 (CRHR2), FKBP5 and the glucocorticoid receptor (NR3C1). We performed multiple linear regression models of methylation M-values to a categorical variable of hypersexuality, adjusting for depression, dexamethasone non-suppression status, Childhood Trauma Questionnaire total score and plasma levels of TNF-alpha and IL-6. Of 76 tested individual CpG sites, four were nominally significant (p<0.05), associated with the genes CRH, CRHR2 and NR3C1. Cg23409074-located 48bp upstream of the transcription start site of the CRH gene - was significantly hypomethylated in hypersexual patients after corrections for multiple testing using the FDR-method. Methylation levels of cg23409074 were positively correlated with gene expression of the CRH gene in an independent cohort of 11 healthy male subjects. The methylation levels at the identified CRH site, cg23409074, were significantly correlated between blood and four different brain regions. CRH is an important integrator of neuroendocrine stress responses in the brain, with a key role in the addiction processes. Our results show epigenetic changes in the CRH gene related to hypersexual disorder in men.

Flibanserin.

OBJECTIVE: To review pivotal clinical trials, pharmacology, contraindications, precautions, and key patient education points of flibanserin for the treatment of hypoactive sexual desire disorder (HSDD) in premenopausal women. DATA SOURCES: A literature search of PubMed using the key words flibanserin and HSDD was conducted in September 2015. There was no time frame to exclude relevant clinical trials. All trials referenced were published between March 2012 and June 2014. Other relevant information was obtained from the Food and Drug Administration (FDA) Web site, press releases, prescribing information from the manufacturer, and ClinicalTrials.gov . STUDY SELECTION/DATA EXTRACTION: All articles in the English language and involving human subjects were reviewed. DATA SYNTHESIS: There are three 24-week, multicenter, randomized, double-blind, placebo-controlled trials that evaluated the efficacy of flibanserin in North American premenopausal women with HSDD. There was 1 trial that studied the effects of flibanserin in postmenopausal women. In all of the trials, the investigators found statistical significant improvements in Female Sexual Function Index (FSFI) desire domain score and satisfying sexual events (SSEs). The most frequently reported adverse events in all flibanserin arms of treatment were somnolence, dizziness, and nausea. CONCLUSION: Flibanserin, a novel, nonhormonal agent that modulates excitatory and inhibitory neurotransmitters was studied in premenopausal women and has shown efficacy in improving sexual desire and SSEs.

Treatment for hypoactive sexual desire.

Flibanserin acts at cortical, limbic, hypothalamic, and brainstem nuclei to inhibit serotonin release by binding to 5-HT1A autoreceptors and block postsynaptic action of serotonin at 5-HT2A receptors. This gradually disinhibits the turnover of other monoamines like dopamine and noradrenaline that are critical for sexual desire.

Sex drive and sexual desire.

PURPOSE OF REVIEW: Loss of sexual desire is increasingly recognized as a consequence of many disease processes, and one that can have a significant negative impact on quality of life. This review explores the biological and psychological aspects of desire, as well as the aetiology and therapeutic options for loss of desire. RECENT FINDINGS: Discoveries have been made in terms of the physiology of desire in men, in that it is affected by estradiol as well as testosterone. It has also been shown that desire is less gender specific in androphilic women than in androphilic men and gynaephilic men and women. Fatigue has been described as the most common self-reported cause of loss of desire, with communication as the most common method for addressing this. In men, a clear distinction has been shown between disorders of arousal and disorders of desire, suggesting that they should remain as separate conditions in the Diagnostic and Statistical Manual of Mental Disorders criteria. Loss of desire has been proven to be a significant consequence of diabetes, multiple sclerosis and polycystic ovary syndrome and can occur as a side-effect of statins and 5α-reductase inhibitors. Testosterone therapy may be an effective treatment for loss of desire in both men and women, and is safe in the treatment of men who have been treated for prostate cancer. It also has a significant impact on desire when used in the treatment of individuals with gender dysphoria. Nonhormonal treatments including flibanserin and new methods of therapy may also be effective. SUMMARY: Loss of desire is underrecognized as a symptom of disease or as a complaint in its own right. As further developments in treatment options, both therapies based and pharmacological, are made, it is increasingly important that clinicians enquire about sexual dysfunction, including loss of desire, at every consultation.

Mechanism of action of flibanserin, a multifunctional serotonin agonist and antagonist (MSAA), in hypoactive sexual desire disorder.

Flibanserin is a novel multifunctional serotonin agonist and antagonist (MSAA) that improves sexual functioning in premenopausal women who suffer from reduced sexual interest and desire.

Chronic stress and sexual function in women.

INTRODUCTION: Chronic stress is known to have negative effects on reproduction, but little is known about how it affects the sexual response cycle. The present study examined the relationship between chronic stress and sexual arousal and the mechanisms that mediate this relationship. AIM: The aim of this study is to test the relationship between chronic stress and sexual arousal and identify mechanisms that may explain this relationship. We predicted that women experiencing high levels of chronic stress would show lower levels of genital arousal and dehydroepiandrosterone (DHEAS) and higher levels of cortisol and cognitive distraction compared with women with average levels of stress. METHODS: Women who were categorized as high in chronic stress (high stress group; n=15) or average in chronic stress (average stress group; n=15) provided saliva samples and watched an erotic film while having their genital and psychological arousal measured. MAIN OUTCOME MEASURES: Main outcome measures were vaginal pulse amplitude, psychological arousal, salivary cortisol, salivary DHEAS, and heart rate and compared them between women with high and average levels of chronic stress. RESULTS: Women in the high stress group had lower levels of genital, but not psychological arousal, had higher levels of cortisol, and reported more distraction during the erotic film than women in the average stress group. The main predictor of decreased genital sexual arousal was participants' distraction scores. CONCLUSIONS: High levels of chronic stress were related to lower levels of genital sexual arousal. Both psychological (distraction) and hormonal (increased cortisol) factors were related to the lower levels of sexual arousal seen in women high in chronic stress, but distraction was the only significant predictor when controlling for other variables.

A phase 2a multicenter, double-blind, placebo-controlled, crossover trial to investigate the efficacy, safety, and toleration of CP-866,087 (a high-affinity mu-opioid receptor antagonist) in premenopausal women diagnosed with female sexual arousal disorder (FSAD).

INTRODUCTION: Female sexual arousal disorder (FSAD) is a condition that can affect women of all ages and have a significant negative impact on emotional well-being. AIMS: The aim of this study is to prospectively evaluate the effects of CP-866,087, a selective mu-opioid receptor antagonist, in premenopausal women with FSAD. METHODS: The study included 51 women (20-45 years of age) with FSAD. All women received placebo and two of three planned doses of CP-866,087 (1, 3, and 10 mg) for 6 weeks in each of three double-blind treatment periods. Efficacy was determined through a series of measures to assess sexual functioning, sexual activity, sexual distress, and perceived meaningful benefit as a result of treatment. In addition, a semi-structured exit interview was conducted at the end of the fourth treatment period or withdrawal to provide a more in-depth, qualitative description of the participants' symptoms, response to treatment, and treatment satisfaction to augment the quantitative assessments. MAIN OUTCOME MEASURES: The within-subject differences from placebo in the change from baseline were compared across a range of measures of sexual function. Summary statistics and 90% confidence intervals were calculated. A qualitative analysis of the exit interview was conducted based on grounded theory methods. RESULTS: Although improvements were seen with CP-866,087 in the key efficacy end points, there was no clinical treatment benefit over placebo. The exit interview analysis suggested that being part of the study and taking positive action to search for a solution to the women's sexual disorder may have been a significant factor in the behavioral changes that were seen, as opposed to the drug treatment itself. CONCLUSIONS: Discerning the potential benefit of pharmacotherapy in a heterogeneous condition such as FSAD is challenging. Participation in a clinical trial combined with a commitment to actively engage in sexual activity may in itself create an environment that is conducive to symptom improvement.

The use of dehydroepiandrosterone in the treatment of hypoactive sexual desire disorder: a report of gender differences.

Data regarding the efficacy of dehydroepiandrosterone (DHEA) in the treatment of hypoactive sexual desire disorder (HSDD) are scarce and inconsistent. We aimed to determine possible gender differences in the efficacy of DHEA as a treatment for HDSS. Postmenopausal women (n=27), and men (n=21) with HSDD, were randomized to receive either DHEA 100 mg daily or placebo for 6 weeks in a controlled, double blind study. Primary outcome measures were sexual function questionnaires. Hormone serum levels of DHEAS, total and bioavailable testosterone, estradiol, and urine levels of DHEA and androsterone were also measured. Participants on active treatment showed a significant increase in circulating serum levels of DHEAS, while bioavailable testosterone levels increased in women only. In women only, significant interaction effects were observed for sexual arousal (p<0.05), satisfaction (p<0.05), and cognition (trend; p=0.06). For arousal, a significant improvement was observed for the DHEA treated group at 6 weeks (p=0.001). Significant correlations were observed between bioavailable T and sexual cognitions, arousal and orgasm, while DHEAS was correlated with satisfaction. In the men, significant correlations were observed between testosterone and arousal (r=.45), sexual drive (r=.50) and orgasm (r=.55). In women with HSDD, DHEA treatment had a significant beneficial effect on arousal, whereas no efficacy was demonstrated in men, indicating a possible gender difference. This improvement seems to be mediated via DHEA's metabolism to testosterone. Our positive results suggest that the neurosteroid DHEA may be effective as a treatment for women with HSDD if administered at a dose of at least 100 mg per day.

[Treatment of premature ejaculation]. / Leczenie wytrysku przedwczesnego.

Premature ejaculation is the most common sexual dysfunction in men. Its prevalence rate in Europe and in United States is estimated to be between 20% and 30%. The diagnosis of premature ejaculation is based on three main criteria: increased intravaginal ejaculatory latency time (IELT), lack of control over ejaculation and interpersonal psychological disturbances. Premature ejaculation is classified as lifelong (primary) or acquired (secondary) and might be facilitated by chronic prostatitis, diabetes mellitus, hyperthyroidism, obesity. The exact etiology of the disease remains unclear, although 5-HT (5-hydroxytryptamine) receptors are known to have a significant role. The use of SSRIs (selective serotonine reuptake inhibitors) is old and efficient form of therapy for premature ejaculation. Other drugs like tramadol, clomipramine, local anaesthetics and PDE-5 (phosphodiesterase 5) inhibitors also have some efficacy in the treatment of premature ejaculation. To minimize adverse effects the "on demand" therapy is preferred to the daily treatment. Simple questionnaires for patients are used to assess treatment effects.

Sexual desire, sexual arousal and hormonal differences in premenopausal US and Dutch women with and without low sexual desire.

The interaction between women's hormonal condition and subjective, physiological, and behavioral indices of desire or arousal remains only partially explored, in spite of frequent reports from women about problems with a lack of sexual desire. The present study recruited premenopausal women at two sites, one in the United States and the other in the Netherlands, and incorporated various measures of acute changes in sexual desire and arousal. A sample of 46 women who met criteria for Hypoactive Sexual Desire Disorder (HSDD) was compared to 47 women who experienced no sexual problems (SF). Half of each group used oral contraceptives (OCs). The specific goal was to investigate whether there is a relationship between women's hormone levels and their genital and subjective sexual responsiveness. Background demographics and health variables, including oral contraceptive (OC) use, were recorded and hormones (total testosterone (T), free testosterone (FT), SHBG, and estradiol) were analyzed along with vaginal pulse amplitude and self-report measures of desire and arousal in response to sexual fantasy, visual sexual stimuli, and photos of men's faces. Self-reported arousal and desire were lower in the HSDD than the SF group, but only for women who were not using oral contraceptives. Relationships between hormones and sexual function differed depending on whether a woman was HSDD or not. In line with prior literature, FT was positively associated with physiological and subjective sexual arousal in the SF group. The HSDD women demonstrated the opposite pattern, in that FT was negatively associated with subjective sexual responsiveness. The findings suggest a possible alternative relationship between hormones and sexual responsiveness in women with HSDD who have characteristics similar to those in the present study.

Citalopram (antidepressant) administration causes sexual dysfunction in male mice through RF-amide related peptide in the dorsomedial hypothalamus.

Citalopram is the most potent selective serotonin reuptake inhibitor (SSRI) which is used as an antidepressant but causes sexual dysfunction. Whether citalopram induced sexual dysfunction is a result of gonadotropin-releasing hormone (GnRH), kisspeptin or RF-amide related peptide (RFRP) alteration is unknown. In this study, we tested mice for sexual behavior after vehicle (0.9% NaCl) and citalopram treatment (5 mg/kg) daily for 1 day (acute) and 21 or 28 days (chronic). Effects of acute and chronic treatments on neuronal numbers and mRNA expression of GnRH, kisspeptin and RFRP were measured. In addition, RFRP fiber projections to preoptic (POA)-GnRH neurons were analyzed using double-label immunohistochemistry. The expression of 14 different serotonin receptor types mRNA was examined in immunostained laser dissected single RFRP neurons in the dorsomedial hypothalamus (DMH), however only 11 receptors types were identified. Acute citalopram treatment did not affect sexual behavior, whereas, the total duration of intromission was reduced with chronic treatment. There was no effect in the expression of kisspeptin (neuronal numbers and mRNA) in the anteroventral periventricular nucleus and the arcuate nucleus and expression of GnRH (neuronal numbers and mRNA) in the POA after citalopram treatment. However, RFRP neuronal numbers in the DMH and fiber projections to the POA were significantly increased after chronic citalopram treatment, which suggests citalopram induced inhibition of sexual behavior involves the modulation of RFRP through serotonin receptors in the DMH.