The use of monoamine pharmacological agents in the treatment of sexual dysfunction: evidence in the literature

Sexual dysfunction and commonly used drugs in neurology

Sexual dysfunction is common in men and women with neurological diseases. Medications used in neurology can cause sexual dysfunction independently of the disease process and this may adversely affect patients' quality of life. This review focuses on medications commonly prescribed to neurological patients that may contribute to altered sexual function, and discusses how they may differ in men and women.

The effects of bupropion on sexual dysfunction in female patients with multiple sclerosis: A double-blind randomized clinical trial

BACKGROUND

Sexual dysfunction (SD) is one of the most common complications of multiple sclerosis (MS). The aim of this study was to evaluate the effects of bupropion on SD among female patients with MS.

METHODS

This double-blind placebo-control randomized clinical trial was conducted on MS patients with SD complaint. Diagnosis was based on the secondary SD subscale scores of the Multiple Sclerosis Intimacy and Sexuality Questionnaire-19 (MSISQ-19). Accordingly, individuals scoring above 27 based on this scale were diagnosed with SD. The subjects were randomly assigned to the bupropion and placebo groups. Bupropion was administered 75 mg twice daily for twelve weeks. As for the study outcomes, besides MSISQ-19, quality of life (Multiple Sclerosis Quality Of Life-54 (MSQOL-54)), fatigue (Multidimensional Fatigue Inventory (MFI)), depression and anxiety (Hospital Anxiety and Depression Scale), and bupropion tolerability were assessed at baseline as well as at weeks 6 and 12.

RESULTS

From 84 patients who met the inclusion criteria, 64 patients completed the trial and were analyzed. Demographics and baseline clinical characteristics were not significantly differed between the two groups. The results showed the mean score of MSISQ-19 from baseline to the end of the study period significantly improved in the bupropion group compared with the placebo (week 6: P: 0.03; week 12: P: 0.03). Similarly, MFI scores showed significant improvement in the bupropion group compared with the placebo group (P: 0.001). Both anxiety and depression scores showed significant alterations at study interval between the two groups (Anxiety: weeks 6 and 12: P:0.04; depression: week 6: 0.01, week 12: 0.02). However, there was no significant change in the MSQOL-54 score between the two groups.

CONCLUSION

The results of the study substantiated that bupropion can be an effective agent for SD improvement in female patients with MS. Further clinical trials with larger sample sizes can more accurately evaluate the observed findings.

Relative Safety and Efficacy of Two Doses of Tandospirone Citrate for Generalized Anxiety Disorder: A Multicenter Randomized Controlled Trial

PURPOSE

To determine the relative safety and efficacy of different doses of tandospirone in treating generalized anxiety disorder (GAD).

PATIENTS AND METHODS

This parallel randomized controlled trial enrolled patients with GAD from eight centers in China. The patients were randomly assigned to 60 mg/day or 30 mg/day tandospirone groups. The primary endpoint was the overall response rate after receiving 6-week treatment. The secondary endpoints included significant response rate, clinical recovery rate, change in the Hamilton Anxiety Scale (HAMA) total score, HAMA subscale score, Hamilton Depression Scale-17 (HAMD-17), Clinical Global Impression-Severity Scale (CGI-S) score, and Impression-Improvement scale (CGI-I) score.

RESULTS

No significant difference was found in the overall response rate between the two groups (65.7% vs 58.4%, p = 0.213). A higher significant response rate and change in the HAMA total score were found in the 60 mg/day group. The reduction in the CGI-S score and percentage of patients with a CGI-I score of ≤2 were higher in 60 mg/day group. The reduction in HAMA somatic anxiety factor, cardiovascular symptom factor, gastrointestinal symptom factor, and HAMD-17 score were more significant in the 60 mg/day group. The incidence of total adverse events was higher in the 60 mg/day group than in the 30 mg/day group. No significant difference was found in the proportion of withdrawal due to adverse events.

CONCLUSION

Both 60 mg/day and 30 mg/day tandospirone show good efficacy in treating patients with GAD. High doses of tandospirone may have advantages in relieving the somatic symptoms but also present disadvantages due to their high level.

TRIAL REGISTRATION

The trial registration no. was NCT01614041.

Vilazodone for Major Depression in Adults: Pharmacological Profile and an Updated Review for Clinical Practice

This article provides an updated review of the pharmacological profile and available efficacy and tolerability/safety data for vilazodone, one of the most recent antidepressant drugs to be approved in the USA for the treatment of major depressive disorder (MDD) in adults. The efficacy of vilazodone for MDD in adults is supported by four positive short-term (8-10 weeks), randomized, placebo-controlled trials. Beyond these pivotal trials, we review updated research findings pertaining to the clinical effects of vilazodone for MDD including the results of switch studies, small comparative efficacy trials, key pooled and secondary data analyses focused on important depressive subtypes (anxious depression) and predictors of treatment outcome, and safety studies including direct studies of sexual side-effects. Despite these additional research efforts and use for over a decade, important gaps in the clinical evidence base remain with vilazodone. Hypothesized differences in efficacy and adverse effects between other antidepressants and vilazodone based on its multimodal mechanism of action (combining serotonin reuptake inhibition with serotonin 5-HT1A partial agonist effects) have not been comprehensively demonstrated in clinical studies and its effectiveness as a continuation- or maintenance-phase therapeutic is not yet established. Questions remain regarding its reproductive and lactational safety profiles and its efficacy as a potential next-step therapeutic for patients with MDD who do not respond to first-line antidepressants such as selective serotonin reuptake inhibitors. Suggestions for clinical use of vilazodone and discussion of its place among the broad range of pharmacotherapies for adults with MDD are provided.

Pharmacotherapy of Anxiety Disorders: Current and Emerging Treatment Options

(Appeared originally in Frontiers in Psychiatry 2020 Dec 23; 11:595584)

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.

Pharmacotherapy of Anxiety Disorders: Current and Emerging Treatment Options

Anxiety disorders are the most prevalent psychiatric disorders and a leading cause of disability. While there continues to be expansive research in posttraumatic stress disorder (PTSD), depression and schizophrenia, there is a relative dearth of novel medications under investigation for anxiety disorders. This review's first aim is to summarize current pharmacological treatments (both approved and off-label) for panic disorder (PD), generalized anxiety disorder (GAD), social anxiety disorder (SAD), and specific phobias (SP), including selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), azapirones (e.g., buspirone), mixed antidepressants (e.g., mirtazapine), antipsychotics, antihistamines (e.g., hydroxyzine), alpha- and beta-adrenergic medications (e.g., propranolol, clonidine), and GABAergic medications (benzodiazepines, pregabalin, and gabapentin). Posttraumatic stress disorder and obsessive-compulsive disorder are excluded from this review. Second, we will review novel pharmacotherapeutic agents under investigation for the treatment of anxiety disorders in adults. The pathways and neurotransmitters reviewed include serotonergic agents, glutamate modulators, GABAergic medications, neuropeptides, neurosteroids, alpha- and beta-adrenergic agents, cannabinoids, and natural remedies. The outcome of the review reveals a lack of randomized double-blind placebo- controlled trials for anxiety disorders and few studies comparing novel treatments to existing anxiolytic agents. Although there are some recent randomized controlled trials for novel agents including neuropeptides, glutamatergic agents (such as ketamine and d-cycloserine), and cannabinoids (including cannabidiol) primarily in GAD or SAD, these trials have largely been negative, with only some promise for kava and PH94B (an inhaled neurosteroid). Overall, the progression of current and future psychopharmacology research in anxiety disorders suggests that there needs to be further expansion in research of these novel pathways and larger-scale studies of promising agents with positive results from smaller trials.

Effects of tandospirone augmentation in major depressive disorder patients with high anxiety: A multicenter, randomized, parallel-controlled, open-label study

BACKGROUND

High levels of anxiety symptoms are common in individuals with major depressive disorder (MDD). Adjunctive anxiolytics are widely used in such patients; however, only a few studies have examined the strategy using tandospirone. This study aimed to evaluate the efficacy and safety of adjunctive tandospirone in individuals with MDD and high level of anxiety symptoms.

METHODS

A multicenter, randomized, parallel-controlled, open-label study was conducted to evaluate the efficacy and safety of tandospirone coupled with selective serotonin reuptake inhibitors (SSRIs) in patients with MDD and high level of anxiety symptoms. Two hundred and forty-five patients fulfilling the DSM-IV-TR criteria for MDD were randomly assigned to 6 weeks of either SSRIs and tandospirone or SSRIs alone treatment. The efficacy was measured by HAMA total scores, HAMD-17 total scores, and Clinical Global Impressions severity subscale (CGI-S) score.

RESULTS

After a 6-week follow-up, two hundred and thirty patients completed this study. Tandospirone coupled with SSRIs significantly improved depressive and anxiety symptoms compared to monotherapy with SSRIs as assessed by HAMD-17 total score (P = 0.003), HAMA total score (P = 0.010), and CGI-S score at week 6 (P = 0.003). The incidence rate of treatment-emergent adverse events (TEAEs) was similar in both groups; the therapy was well-tolerated.

CONCLUSIONS

Short-term tandospirone augmentation was effective and well-tolerated in this study. Addition of tandospirone may improve outcomes in MDD patients with high anxiety.

EEG to Primary Rewards: Predictive Utility and Malleability by Brain Stimulation

Theta burst stimulation (TBS) is thought to affect reward processing mechanisms, which may increase and decrease reward sensitivity. To test the ability of TBS to modulate response to strong primary rewards, participants hypersensitive to primary rewards were recruited. Twenty men and women with at least two opposite-sex, sexual partners in the last year received two forms of TBS. Stimulations were randomized to avoid order effects and separated by 2 hours to reduce carryover. The two TBS forms have been demonstrated to inhibit (continuous) or excite (intermittent) the left dorsolateral prefrontal cortex using different pulse patterns, which links to brain areas associated with reward conditioning. After each TBS, participants completed tasks assessing their reward responsiveness to monetary and sexual rewards. Electroencephalography (EEG) was recorded. They also reported their number of orgasms in the weekend following stimulation. This signal was malleable by TBS, where excitatory TBS resulted in lower EEG alpha relative to inhibitory TBS to primary rewards. EEG responses to sexual rewards in the lab (following both forms of TBS) predicted the number of orgasms experienced over the forthcoming weekend. TBS may be useful in modifying hypersensitivity or hyposensitivity to primary rewards that predict sexual behaviors. Since TBS altered the anticipation of a sexual reward, TBS may offer a novel treatment for sexual desire problems.

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.

Azapirone 5-HT1A receptor partial agonist treatment for major depressive disorder: systematic review and meta-analysis

BACKGROUND

A meta-analysis of the serotonin1A (5-HT1A) receptor partial agonist of the azapirone class as an anxiolytic drug for the treatment of major depressive disorder (MDD) has not previously been reported.

METHOD

We carried out a systematic review of the literature available in PubMed, the Cochrane Library database and PsycINFO up to 12 October 2013, and conducted a meta-analysis of randomized controlled trials (RCTs) comparing 5-HT1A agonists with placebo and RCTs of 5-HT1A agonist augmentation therapies for MDD treatment. We calculated the risk ratio (RR), number needed to treat (NNT)/number needed to harm (NNH) and 95% confidence intervals (CIs).

RESULTS

Fifteen RCTs comparing 5-HT1A agonists with placebo (total n = 2469, four studies with buspirone, seven with gepirone, three with ipsapirone and one with zalospirone) were identified. Pooled 5-HT1A agonists had significantly more responders (RR 0.74, 95% CI 0.65-083, p < 0.00001, NNT = 6, 12 trials, n = 1816) than placebo. Pooled 5-HT1A agonists were superior to placebo in discontinuation due to inefficacy (RR 0.49, p = 0.02, NNH = 16, p = 0.03, 10 trials, n = 1494) but were inferior to placebo in discontinuation due to side-effects (RR 1.88, p < 0.0001, NNH = 17, p = 0.001, 13 trials, n = 2196). However, all-cause discontinuation was similar in both groups (RR 0.99, p = 0.85, 14 trials, n = 2402). Four 5-HT1A agonist augmentation studies were identified (total n = 365, three buspirone studies and one tandospirone study). There were no statistically significant effects of 5-HT1A agonist augmentation therapies on response rate (RR 0.98, p = 0.85, four trials, n = 341). 5-HT1A agonist-related side-effects including gastrointestinal symptoms, dizziness, insomnia, palpitation, paresthesia and sweating were greater than with placebo (p < 0.00001 to p = 0.03).

CONCLUSIONS

Our results suggest that 5-HT1A agonist has a more beneficial effect on MDD than placebo, but has several side-effects.

Pharmacology of serotonin and female sexual behavior

In this review, first a historical perspective of serotonin's (5-HT) involvement in female sexual behavior is presented. Then an overview of studies implicating 5-HT is presented. The effect of drugs that increase or decrease CNS levels of 5-HT is reviewed. Evidence is presented that drugs which increase 5-HT have negative effects on female sexual behavior while a decrease in 5-HT is associated with facilitation of sexual behavior. Studies with compounds that act on 5-HT₁, 5-HT₂ or 5-HT₃ receptors are discussed. Most evidence indicates that 5-HT₁A receptor agonists inhibit sexual behavior while 5-HT₂ or 5-HT₃ receptors may exert a positive influence. There is substantial evidence to support a role for 5-HT in the modulation of female consummatory sexual behavior, but studies on the role of 5-HT in other elements of female sexual behavior (e.g. desire, motivation, sexual appetite) are few. Future studies should be directed at determining if these additional components of female sexual behavior are also modulated by 5-HT.

An update on the pharmacological management of female sexual dysfunction

INTRODUCTION

Female sexual dysfunction (FSD) is a global health issue, with as many as 12% of women over 18 years old reporting sexual difficulties associated with distress. It is a multifaceted problem with psychological and biological causes. Affected women tend to have an impaired quality of life, a decreased level of well-being and relationship issues. Hence there is a need for management options for affected women.

AREAS COVERED

This paper focuses on current pharmacological options for the treatment of FSD, particularly estrogens and androgens, which have been extensively studied. Some investigational drugs are also described, including the centrally acting agents such as flibanserin and bupropion, and intravaginal DHEA and testosterone, which may be useful as an alternative for women with specific conditions, such as breast cancer survivors.

EXPERT OPINION

Although approval for the use of testosterone for treatment of FSD is limited to some European countries and restricted to surgically menopausal women, there is extensive off-label use for this purpose. No other product has yet achieved regulatory approval for treatment of FSD. Completion of studies of nonhormonal FSD therapies and safety studies of testosterone may result in regulatory approval of such products for the treatment of FSD in the near future.

Polymorphic variants of neurotransmitter receptor genes may affect sexual function in aging males: data from the HALS study

BACKGROUND/AIMS

Human behavior is influenced by a number of brain neurotransmitters. Central dopamine, serotonin and melanocortin systems have special importance for male sexual function. We searched for associations between male aging symptoms and polymorphic sites of serotonin (5-HTR1B), melanocortin (MC4R) and dopamine (DRD2, DRD4) receptors.

METHODS

In a population-based sample, genotyping of 5-HTR1B (polymorphism: G861C), MC4R (polymorphisms: C-2745T, Val103Ile), DRD2 (polymorphism: C313T) and DRD4 (polymorphism: 48-bp VNTR) was performed in 387 healthy men. The Aging Males' Symptoms (AMS) scale was used to evaluate specific ailments of aging men. We analyzed answers to questions from the AMS scale. Five points of the questionnaire addressed sexual symptoms of the aging male: feeling of passing one's peak, decrease in beard growth, decrease in ability/frequency to perform sexually, decrease in the number of morning erections, and decrease in sexual desire/libido (lacking pleasure in sex, lacking desire for sexual intercourse). Relations between reported symptoms and variants of the polymorphic sites of the studied genes were assessed.

RESULTS

After adjusting for confounding factors (education, arterial hypertension, physical activity, weight, waist circumference) an association between the sexual dimension of AMS and genetic variants of 5-HTR1B G861C (p = 0.04) was observed.

CONCLUSIONS

Variability of neurotransmitter receptor genes may be associated with sexual symptoms of aging in men.

Agomelatine: an antidepressant without deterioration of sexual response

Sexual dysfunctions caused by the use of antidepressants are relatively common. Agomelatine has demonstrated antidepressant properties in comparative studies with sertraline, fluoxetine, and venlafaxine as active controls. The aim of this study was to evaluate the effects of agomelatine on sexual response. Acutely depressed patients (n = 25) treated with agomelatine (25-50 mg/day) were evaluated over 12 weeks. Agomelatine showed a favorable response on depressive symptoms using the Montgomery-Åsberg Depression Rating Scale throughout the study. The Clinical Global Impression improvement score at the end of the study was 1.70 (SD = 0.89). The author assessed sexual response using the Arizona Sexual Experiences Scale, the International Index of Erectile Function, and a Visual Analogue Scale for desire, arousal, time, and intensity of orgasm and vaginal lubrication. Arizona Sexual Experiences Scale scores improved after 3 weeks of treatment, mainly attributable to an improvement in women rather than in men. The Visual Analogue Scale showed improvement in all stages of sexual response in women, with minimal changes in men. Clinical Satisfaction Scores at the end of the study for all patients were 7.00 (SD = 1.53). In conclusion, agomelatine appears to be a good option for the treatment of depression because it would not have adverse effects on sexual function.

Managing Low Sexual Desire in Women

Low sexual desire is a prevalent symptom, but not one frequently volunteered by women. When accompanied by distress, loss of libido is known as hypoactive sexual desire disorder, which can have a significant impact on a woman's wellbeing. The etiology of hypoactive sexual desire disorder is multifactorial and its management requires a combination of psychosocial and pharmacological interventions. This article outlines the assessment of patients presenting with the symptom of low sexual desire and discusses the evidence for pharmacological management.