Two novel combined drug treatments for women with hypoactive sexual desire disorder

Interplay between sexual excitation and inhibition: impact on sexual function and neural correlates of erotic stimulus processing in women

Background

As outlined by the dual control model (DCM), individual differences in the regulation of sexual arousal following sexual stimulation depend on two distinct neurophysiological processes: sexual excitation (SE) and sexual inhibition (SI). Although associations with sexual function, behavior, and cue processing have been demonstrated in previous research, underlying neural correlates remain insufficiently explored. Moreover, interactive effects of SE/SI as proposed by the DCM, as well as factors impacting SE/SI properties, such as the use of oral contraceptives (OCs), have not received adequate attention in existing research.

Methods

90 healthy, sexually active women (n = 51 using OCs, n = 39 naturally cycling) completed an Emotional-Picture-Stroop-Paradigm (EPSP) while a 64-channel EEG was recorded. LPP amplitudes toward erotic and neutral stimuli were consecutively computed as a marker of motivational salience and approach motivation. Additionally, women provided self-reports of SE/SI and sexual function. Moderation analyses were performed to assess interactive effects of SE/SI in predicting LPP amplitudes and sexual function.

Results

Sexual function was negatively associated with SI levels but unrelated to SE. Higher SI was associated with reduced LPP amplitudes in response to erotic stimuli. This negative association was, however, attenuated for women high in SE, suggesting interactive effects of SE/SI. Furthermore, women using OCs reported lower SE compared to naturally cycling women.

Conclusion

The observed findings provide additional psychophysiological evidence supporting the DCM and underscore the relevance of interactive SE/SI effects in stimulus processing and approach motivation. They also highlight the possible impact of OCs on psychosexual variables that warrants further research.

The Dual Control Model of Sexual Response: A Scoping Review, 2009-2022

The Dual Control Model proposes that sexual arousal and related processes are dependent on the balance between sexual excitation and sexual inhibition, and that individuals vary in their propensity for these processes. This scoping review provides an overview and discussion of the questionnaires used to measure the propensities for sexual excitation and inhibition, their translation and validation in other languages, and their application in empirical research on topics ranging from sexual desire and arousal, sexual (dys)function, sexual risk taking, asexuality, hypersexuality, and sexual aggression. A total of 152 papers, published between 2009 and 2022 and identified using online databases, were included in this review. The findings, consistent with those reviewed by Bancroft et al. (2009), suggest that sexual excitation is particularly relevant to sexual desire and responsivity and predictive of asexuality and hypersexuality. Sexual inhibition plays a role in sexual dysfunction. sexual risk taking, and sexual aggression, although often in interaction with sexual excitation. Suggestions for the further development of the model and for future studies are discussed.

Introducing sexual dysfunction in mental care

Introduction: People with any psychiatric disorder tend to have difficulties in responding sexually. However,sexual dysfunction (SD) is usually under-recognized, even the tightly hormonal and neuronal common connexions through the brain-sex axis. Multiple sources of resistance to SD assessment and intervention persist. Areas covered: The present review aims to underline the feasibility to introduce SD evaluation in patients with any psychiatric disorders, evaluating the potential mutual benefits of their management. Expert opinion: Women and men living with mental disorders frequently display sexual difficulties; however, some of them consider sexuality as a relevant parameter of their quality of life. In fact, SD as a side effect is a frequent reason for stopping the intake of medication. What is more, a holistic approach integrating sexual function could foster a better understanding of mental pathologies due to a common origin of pathogenesis. This could improve care quality, in keeping with the global tendency toward the development of personalized medicine. Consistently, the integration of SD assessment is highly recommended in mental health, all the more so when a psychotropic drug is prescribed. An expected consequence would be a reconstruction of the healthcare professional's consideration for the sexuality of people experiencing mental disorders.

Female Hypoactive Sexual Desire Disorder: A Practical Guide to Causes, Clinical Diagnosis, and Treatment

Hypoactive sexual desire disorder (HSDD) in women is defined as the persistent or recurrent absence of sexual thoughts or fantasies and/or lack of desire for sexual activity that is associated with marked personal distress and/or interpersonal difficulties, and cannot be better attributed to another primary disorder, medication, or general medical condition. Notably, HSDD shares some similarity with depression, as its etiology can be explained using a biopsychosocial model that includes biological, psychological, and sociocultural factors, as well as interpersonal influences. Due to its high prevalence and negative impact on the overall health and well-being of women, primary care health professionals and women's health practitioners need to be actively aware of HSDD, particularly because patients may be reluctant or unwilling to initiate a discussion about their sexual concerns during routine visits. HSDD is well established as a valid and treatable clinical entity. Even for those inexperienced in treating sexual problems, there are simple and validated screening tools such as the Decreased Sexual Desire Screener that can help identify HSDD and a need for further evaluation and treatment. There have been few established pharmacologic treatments for HSDD. Flibanserin was the first drug approved for the treatment of HSDD by the U.S. Food and Drug Administration (FDA). Bremelanotide, a novel melanocortin receptor agonist, was recently approved by the FDA for the treatment of acquired, generalized HSDD in premenopausal women. Increased awareness and recognition of HSDD as a medical condition should provide an incentive for further clinical development of effective treatments for HSDD.

Aromatization Is Not Required for the Facilitation of Appetitive Sexual Behaviors in Ovariectomized Rats Treated With Estradiol and Testosterone

Testosterone can be safely and effectively administered to estrogen-treated post-menopausal women experiencing hypoactive sexual desire. However, in the United States and Canada, although it is often administered off-label, testosterone co-administered with estradiol is not a federally approved treatment for sexual arousal/desire disorder, partly because its mechanism is poorly understood. One possible mechanism involves the aromatization of testosterone to estradiol. In an animal model, the administration of testosterone propionate (TP) given in combination with estradiol benzoate (EB) significantly increases sexually appetitive behaviors (i.e., solicitations and hops/darts) in ovariectomized (OVX) Long-Evans rats, compared to those treated with EB-alone. The goal of current study was to test whether blocking aromatization of testosterone to estradiol would disrupt the facilitation of sexual behaviors in OVX Long-Evans rats, and to determine group differences in Fos immunoreactivity within brain regions involved in sexual motivation and reward. Groups of sexually experienced OVX Long-Evans rats were treated with EB alone, EB+TP, or EB+TP and the aromatase inhibitor Fadrozole (EB+TP+FAD). Females treated with EB+TP+FAD displayed significantly more hops and darts, solicitations and lordosis magnitudes when compared to EB-alone females. Furthermore, TP, administered with or without FAD, induced the activation of Fos-immunoreactivity in brain areas implicated in sexual motivation and reward including the medial preoptic area, ventrolateral division of the ventromedial nucleus of the hypothalamus, the nucleus accumbens core, and the prefrontal cortex. These results suggest that aromatization may not be necessary for TP to enhance female sexual behavior and that EB+TP may act via androgenic pathways to increase the sensitivity of response to male-related cues, to induce female sexual desire.

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.

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.

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.

Female Sexual Dysfunction-Medical and Psychological Treatments, Committee 14

INTRODUCTION

Since the millennium we have witnessed significant strides in the science and treatment of female sexual dysfunction (FSD). This forward progress has included (i) the development of new theoretical models to describe healthy and dysfunctional sexual responses in women; (ii) alternative classification strategies of female sexual disorders; (iii) major advances in brain, hormonal, psychological, and interpersonal research focusing on etiologic factors and treatment approaches; (iv) strong and effective public advocacy for FSD; and (v) greater educational awareness of the impact of FSD on the woman and her partner.

AIMS

To review the literature and describe the best practices for assessing and treating women with hypoactive sexual desire disorder, female sexual arousal disorder, and female orgasmic disorders.

METHODS

The committee undertook a comprehensive review of the literature and discussion among themselves to determine the best assessment and treatment methods.

RESULTS

Using a biopsychosocial lens, the committee presents recommendations (with levels of evidence) for assessment and treatment of hypoactive sexual desire disorder, female sexual arousal disorder, and female orgasmic disorders.

CONCLUSION

The numerous significant strides in FSD that have occurred since the previous International Consultation of Sexual Medicine publications are reviewed in this article. Although evidence supports an integrated biopsychosocial approach to assessment and treatment of these disorders, the biological and psychological factors are artificially separated for review purposes. We recognize that best outcomes are achieved when all relevant factors are identified and addressed by the clinician and patient working together in concert (the sum is greater than the whole of its parts). Kingsberg SA, Althof S, Simon JA, et al. Female Sexual Dysfunction-Medical and Psychological Treatments, Committee 14. J Sex Med 2017;14:1463-1491.

Facilitation of sexual behavior in ovariectomized rats by estradiol and testosterone: A preclinical model of androgen effects on female sexual desire

In the United States and Canada, there are no approved treatments for hypoactive sexual desire disorder in postmenopausal women. Testosterone improves female sexual desire in naturally- and surgically-menopausal women maintained on estrogen replacement therapy, and long-term safety data from randomized placebo-controlled clinical trials has yielded promising results. However, the mechanisms associated with its efficacy are not known, and could be addressed using preclinical rodent models; yet there is no systematic evaluation of the effects of estradiol and testosterone on female rat sexual behavior. The aim of these studies was to assess whether testosterone propionate (TP) facilitates sexual behaviors, particularly appetitive sexual behaviors, in Long-Evans and Wistar ovariectomized (OVX) rats primed with estradiol benzoate (EB). In Experiment 1, Long-Evans OVX rats were treated with Oil (O), 10μg EB+O, O+200μg TP, 10μg EB+500μg progesterone (P), or 10μg EB+200μg TP. In Experiment 2a, Wistar OVX rats were treated with varying doses of EB (2.5, 5, or 10μg) 48h prior, and TP (0, 200, or 400μg) 4h prior to testing in a Latin-Square design. A subset of animals was used in Experiment 2b and treated sequentially with EB (0, 2.5, 5, or 10μg) followed by TP (0, 200, or 400μg, in a Latin-Square design) 48h prior to sexual behavior testing. All tests occurred in the bilevel pacing chamber. Frequencies of female appetitive (hops/darts, solicitations, level changes) and consummatory (lordosis quotient and magnitude) sexual behaviors as well as the number of defensive behaviors towards males were scored. Number of mounts, intromissions and ejaculations from males were also scored. In EB-primed OVX Long-Evans rats, 200μg TP administered 4h prior to testing facilitated hops/darts and lordosis ratings beyond EB alone, and to levels equivalent to EB+P. In contrast, that regimen was not successful in EB-primed OVX Wistar rats. When EB and TP were co-administered 48h prior to testing, 10μg EB+200μg TP significantly increased hops/darts and level changes beyond that observed by 10μg EB alone. In summary, the administration of EB and TP to OVX Long-Evans and Wistar rats facilitates appetitive measures of sexual behavior. Strain differences exist that likely reflect underlying differences in sensitivities to EB, and the EB-primed OVX Long-Evans rat may be useful for studying mechanisms of TP-facilitation of desire due to higher baseline sexual inhibition.

Flibanserin for hypoactive sexual desire disorder: place in therapy

The pathophysiology, diagnosis and treatment of female sexual interest in pre- and post-menopausal women present a complex arena for patients and physicians to navigate. Flibanserin was the first pharmacologic treatment, approved by the United States Food and Drug Administration in August 2015, for hypoactive sexual desire disorder (HSDD) in premenopausal women. Side effects, contraindications and lack of approval in postmenopausal women are all limitations, as are issues surrounding patient and physician knowledge and access. Testosterone, buspirone, sildenafil, bupropion, bremelanotide, as well as herbal medications (Herbal vX or Tribulus terrestris) have demonstrated some clinical benefit in women with sexual dysfunction disorders however, trials have significant design, dosing or generalizability limitations. Nonpharmaceutical cognitive behavioral therapy, mindfulness meditation, pelvic floor therapy, and clitoral stimulators are also interventions women may pursue. This manuscript will explore the clinical data regarding these therapeutic modalities so as to bring attention to this issue of female HSDD, to offer an overview of current research, and to incite providers to initiate discussion among themselves and their patients.

The Female Sexual Response: Current Models, Neurobiological Underpinnings and Agents Currently Approved or Under Investigation for the Treatment of Hypoactive Sexual Desire Disorder

How a woman responds to sexual cues is highly dependent on a number of distinct, yet related, factors. Researchers have attempted to explain the female sexual response for decades, but no single model reigns supreme. Proper female sexual function relies on the interplay of somatic, psychosocial and neurobiological factors; misregulation of any of these components could result in sexual dysfunction. The most common sexual dysfunction disorder is hypoactive sexual desire disorder (HSDD). HSDD is a disorder affecting women across the world; a recent in-person diagnostic interview study conducted in the USA found that an estimated 7.4% of US women suffer from HSDD. Despite the disorder's prevalence, it is often overlooked as a formal diagnosis. In a survey of primary care physicians and obstetrics/gynaecology specialists, the number one reason for not assigning an HSDD diagnosis was the lack of a safe and effective therapy approved by the US Food and Drug Administration (FDA). This changed with the recent FDA approval of flibanserin (Addyi™) for the treatment of premenopausal women with acquired, generalized HSDD; there are still, however, no treatments approved outside the USA. HSDD is characterized by a marked decrease in sexual desire, an absence of motivation (also known as avolition) to engage in sexual activity, and the condition's hallmark symptom, marked patient distress. Research suggests that HSDD may arise from an imbalance of the excitatory and inhibitory neurobiological pathways that regulate the mammalian sexual response; top-down inhibition from the prefrontal cortex may be hyperactive, and/or bottom-up excitation to the limbic system may be hypoactive. Key neuromodulators for the excitatory pathways include norepinephrine, oxytocin, dopamine and melanocortins. Serotonin, opioids and endocannabinoids serve as key neuromodulators for the inhibitory pathways. Evolving treatment strategies have relied heavily on these crucial research findings, as many of the agents currently being investigated as treatment options for HSDD target and influence key players within these excitatory and inhibitory pathways, including various hormone therapies and centrally acting drugs, such as buspirone, bupropion and bremelanotide.