Sildenafil for women patients with antidepressant-induced sexual dysfunction

Pharmacologic interventions for antidepressant-induced sexual dysfunction: a systematic review and network meta-analysis of trials using the Arizona sexual experience scale

BACKGROUND

Despite the prevalence of antidepressant-related sexual side effects, comparisons of treatments for these problematic side effects are lacking.

METHODS

To address this, we performed a systematic review and Bayesian network meta-analysis to compare interventions for antidepressant-induced sexual dysfunction in adults. Using PubMed and clinicaltrials.gov, we identified published and unpublished prospective treatment trials from 1985 to September 2020 (primary outcome: the Arizona sexual experience scale [ASEX] score). The quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation framework.

RESULTS

We identified 57 citations (27 randomized controlled trials, 66 treatment arms, 27 open-label trials, and 3 crossover trials) that evaluated 33 interventions (3108 patients). In the systematic review, 44% (25/57) of trials reported successful interventions; this was more common in open-label (70%, 19/27) compared to placebo-controlled studies (22%, 6/27). In the meta-analysis of placebo-controlled studies that used the ASEX (N = 8), pycnogenol was superior to placebo (standardized mean difference: -1.8, 95% credible interval [CrI]: [-3.7 to 0.0]) and there was evidence that, at a 6% threshold, sildenafil improved sexual dysfunction (standardized mean difference: -1.2, 95% CrI [-2.5 to 0.1]). In the meta-analysis including single-arm studies (15 studies), treatment response was more common with sildenafil, tianeptine, maca, tiagabine, and mirtazapine compared to placebo, but these differences failed to reach statistical significance.

CONCLUSIONS

While heterogeneity across randomized controlled trials complicates identifying the single best intervention, multiple trials suggest that sildenafil ameliorates antidepressant-induced sexual dysfunction. More randomized controlled trials are needed to examine the putative efficacy of other interventions.

Female Sexual Dysfunction: Review of the Disorder and Evidence for Available Treatment Alternatives

With the introduction and marketing of sildenafil, national attention has focused on sexual dysfunction in men. However, strides are being made to focus more effort on evaluation and treatment of female sexual disorder (FSD) since a 1999 national survey reported prevalence rates as high as 43% in women. Evaluation and assessment of FSD requires a comprehensive history and physical examination. Understanding of FSD requires knowledge and understanding of sexual anatomy, physiology, and pathophysiology. Nonpharmacologic treatment may include sex therapy or relationship counseling. Pharmacologic treatment of FSD has focused mainly on hormonal therapies, including estrogen and testosterone, with the majority of studies being done in postmenopausal and hysterectomized women. However, recent studies indicate a more prudent and careful use of hormonal therapies. Research is also moving toward evaluation of bupropion and sildenafil as options for women who suffer from FSD. Available evidence for treatment alternatives is scant and in some cases inconclusive.

l-Cys/CSE/H2S pathway modulates mouse uterus motility and sildenafil effect

Sildenafil, a selective phosphodiesterase type 5 (PDE5) inhibitor, commonly used in the oral treatment for erectile dysfunction, relaxes smooth muscle of human bladder through the activation of hydrogen sulfide (H2S) signaling. H2S is an endogenous gaseous transmitter with myorelaxant properties predominantly formed from l-cysteine (l-Cys) by cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE). Sildenafil also relaxes rat and human myometrium during preterm labor but the underlying mechanism is still unclear. In the present study we investigated the possible involvement of H2S as a mediator of sildenafil-induced effect in uterine mouse contractility. We firstly demonstrated that both enzymes, CBS and CSE were expressed, and able to convert l-Cys into H2S in mouse uterus. Thereafter, sildenafil significantly increased H2S production in mouse uterus and this effect was abrogated by CBS or CSE inhibition. In parallel, l-Cys, sodium hydrogen sulfide or sildenafil but not d-Cys reduced spontaneous uterus contractility in a functional study. The blockage of CBS and CSE reduced this latter effect even if a major role for CSE than CBS was observed. This data was strongly confirmed by using CSE(-/-) mice. Indeed, the increase in H2S production mediated by l-Cys or by sildenafil was not found in CSE(-/-) mice. Besides, the effect of H2S or sildenafil on spontaneous contractility was reduced in CSE(-/-) mice. A decisive proof for the involvement of H2S signaling in sildenafil effect in mice uterus was given by the measurement of cGMP. Sildenafil increased cGMP level that was significantly reduced by CSE inhibition. In conclusion, l-Cys/CSE/H2S signaling modulates the mouse uterus motility and the sildenafil effect. Therefore the study may open different therapeutical approaches for the management of the uterus abnormal contractility disorders.

Comparing the Efficacy of Bupropion and Amantadine on Sexual Dysfunction Induced by a Selective Serotonin Reuptake Inhibitor

BACKGROUND

Antidepressant-induced sexual dysfunction (SD) is a common problem, associated with a significant risk of non-adherence. Selective Serotonin Reuptake Inhibitors (SSRIs) are associated with a substantial risk of SD. Only 10 % of patients show spontaneous improvement during follow up period.

OBJECTIVES

This study aimed to compare two proposed medication (bupropion vs. amantadine) in alleviating SD in patients treated with SSRIs.

PATIENTS AND METHODS

In a randomized, single-blinded, clinical trial in Iran, 46 patients were recruited based on DSM-IV-TR criteria and semi-structured interview. Then, they were randomized into two treatment groups using table of random numbers. Eight patients were excluded and finally 38 patients completed the study which lasted for 4 weeks. Twenty patients were given bupropion, 18 patients were randomly assigned to another group, and given amantadine. Patients were assessed with the Arizona sexual experience scale (ASEX) at baseline and 4 weeks after the treatment.

RESULTS

A total of 38 patients completed the study (18 patients in amantadine vs. 20 patients in bupropion).The mean ASEX scores gradually declined in both study groups during the trial. The reduction of ASEX score in bupropion group was more than that of amantadine group that was statistically significant. So, the addition of bupropion at higher doses appears to be more effective approach in comparison with amantadine.

CONCLUSIONS

These results provide empirical support for conducting a further study on comparing different add-on strategies for treating drug-induced SD.

Standard operating procedures for female orgasmic disorder: consensus of the International Society for Sexual Medicine

INTRODUCTION

As the field of sexual medicine evolves, it is important to continually improve patient care by developing contemporary "standard operating procedures" (SOPs), reflecting the consensus view of experts in sexual medicine. Few, if any, consensus SOPs have been developed for the diagnosis and treatment of Female Orgasmic Disorder (FOD).

AIM

The objective is to provide standard operating procedures for FOD.

METHODS

The SOP Committee was composed of a chair, selected by the International Society for the Study of Sexual Medicine, and two additional experts. To inform its key recommendations, the Committee used systematic reviews of available evidence and discussions during a group meeting, conference calls and e-mail communications. The Committee received no corporate funding or remuneration.

RESULTS

A total of 12 recommendations for the assessment and treatment of FOD were generated, including suggestions for further research.

CONCLUSIONS

Evidence-based, practice recommendations for the treatment of FOD are provided that will hopefully inform clinical decision making for those treating this common condition.

Sildenafil citrate for female sexual arousal disorder: a future possibility?

Female sexual arousal disorder (FSAD) is a common disorder encountered in clinical practice, with self-reported arousal difficulties reported in up to 26% of American women. Various oral therapies for FSAD have been studied, including sildenafil citrate, a phosphodiesterase inhibitor that is currently used to treat male erectile dysfunction. In vitro studies of sildenafil citrate have demonstrated smooth-muscle relaxation in clitoral tissue, and phosphodiesterase type-5 has been shown to be present in vaginal, clitoral and labial smooth muscle; these findings have led to theories that sildenafil citrate might be successful for treating FSAD. This Review discusses the data from clinical trials that have assessed sildenafil citrate for the treatment of FSAD; the trials show that sildenafil citrate is moderately effective. Sildenafil citrate may also be effective in women with FSAD secondary to multiple sclerosis, diabetes or antidepressant use; however, more trials in these patient populations are required to confirm these findings.

Oral phosphodiesterase type 5 inhibitors: nonerectogenic beneficial uses

INTRODUCTION

Phosphodiesterase type 5 (PDE5) hydrolyses cyclic guanylate monophosphate (cGMP) specifically to 5' GMP. PDE5 inhibitors were a breakthrough medication that addressed a previously unfulfilled medical need. They promoted vascular relaxation in the corpora cavernosa and penile erection during sexual stimulation. Sildenafil, vardenafil, and tadalafil were approved then introduced as effective treatments for male erectile dysfunction. This impact has stimulated academic, clinical, and industrial research.

AIM

To highlight the nonerectogenic beneficial uses of oral PDE5 inhibitors.

METHOD

A systematic review of published studies in this affair based on a Pubmed and medical subject heading databases search of all concerned articles.

MAIN OUTCOME MEASURES

Demonstrated beneficial as well as applicable uses of oral PDE5 inhibitors.

RESULTS

As chemical molecules, these drugs were shown to exert potential nonerectogenic beneficial effects. They showed efficacy as a useful adjunct in the management of pulmonary hypertension. Additional uses were extended to different utilities: essential hypertension, benign prostatic hyperplasia, gastrointestinal disorders, endothelial dysfunction, female sexual dysfunction, genital blood flow, exercise capacity, Raynaud's phenomenon, sperm motility, etc.

CONCLUSION

Exploring PDE5 inhibitors for their possible medical applications in diverse specialties seems to be beneficial in making use of these molecules for the welfare of humanity.

Mirtazapine augmentation in depressed patients with sexual dysfunction due to selective serotonin reuptake inhibitors

OBJECTIVE

To evaluate the effect of mirtazapine augmentation in patients with sexual dysfunction induced by current selective serotonin reuptake inhibitor (SSRI) treatment.

METHODS

Forty-nine outpatients in remission from major depressive disorder with SSRI treatment and experiencing treatment-emergent sexual dysfunction were invited to participate and 33 (25 women and 8 men) were included in this 8-week open-label study. All patients continued her/his current SSRI treatment (dosages unchanged) and started on mirtazapine augmentation of 15 mg/day during the first week and 30 mg/day throughout the rest of the study. The Hamilton rating scale for depression (HAM-D), the psychotropic-related sexual dysfunction questionnaire (PRSexDQ), and the Golombok and Rust Inventory of Sexual Satisfaction (GRISS) were given to all patients at baseline and at each follow-up (end of the first, second, fourth, sixth, and eight weeks).

RESULTS

Mirtazapine augmentation led to significant reductions in HAM-D, PRSexDQ, and GRISS scores throughout the study especially after week 4 and 48.5% of patients (n = 16) reported that they had no overall sexual dysfunction at the end of the study.

CONCLUSIONS

Mirtazapine augmentation is a good choice for the treatment of SSRI-induced sexual dysfunction, and the results are typically seen later after 4-8 weeks.

A novel approach for predicting antidepressant-induced sexual dysfunction in rats

RATIONALE

Sexual dysfunction is associated with antidepressant discontinuation. Therefore, there is a need for models that predict antidepressant-induced sexual dysfunction.

OBJECTIVE

To develop a predictive method for evaluating antidepressant-induced sexual dysfunction.

METHODS

Male Sprague-Dawley rats were allowed access to sexually receptive females during a single overnight mating session and then treated with antidepressants known to produce differing levels of sexual dysfunction in the clinic. Two to three weeks later, following either acute, subchronic (7-day), or chronic (14-day) antidepressant treatment, rats were observed for penile erections (PE) in the presence of sexually receptive females that were not accessible for contact but served as visual, auditory, and olfactory stimuli in the testing area.

RESULTS

Chronic treatment of fluoxetine (10 mg/kg), desipramine (10 mg/kg), and bupropion (20 mg/kg) reduced the number of PE 71, 53, and 8%, respectively, relative to vehicle-treated rats. This rank order of the compounds' propensity for reducing PE is comparable to the rank order of the compounds' ability to produce sexual dysfunction during antidepressant treatment in the clinic. Additionally, drugs used to treat antidepressant-induced sexual dysfunction in the clinic, such as sildenafil, yohimbine, and dopamine agonists, were also effective in attenuating the deficits in the number of noncontact PE produced by chronic fluoxetine treatment.

CONCLUSIONS

Taken together, this model represents a novel approach for predicting antidepressant-induced sexual dysfunction in rats, which parallels the pattern of reports of sexual dysfunction in the clinic associated with different antidepressant treatments and the ability of adjunct treatment to reverse the sexual impairments produced by antidepressants.

[Sexuality and pharmacotherapy. Medication-induced disorders of sexual response and pharmacotherapeutic options for the treatment of sexual dysfunctions]

This contribution addresses two different areas of the complex relationship between pharmacotherapy and sexual function and dysfunction in men and women. As many impairments of sexual function are caused by side effects of medications, particularly psychotropic drugs, the first part of the paper describes substances and mechanisms often related to sexual dysfunction with a special focus on antidepressants and neuroleptics. While serotonin reuptake inhibitors entail a high risk of sexual dysfunction, it is often difficult to differentiate the negative impact of the drug from the impairment caused by the mental disorder itself. Ways to deal with these dysfunctions and remedial measures are discussed. In the second section, current pharmacological treatments for female and male sexual dysfunctions are reviewed. While there is no approved pharmacotherapy with established efficacy for female sexual dysfunction with the possible exception of the transdermal testosterone patch for surgically menopausal women, effective pharmacological therapies are available for male erectile disorders. In addition, testosterone substitution is the treatment of choice for hypoactive sexual desire disorders caused by hypogonadism. As sexual dysfunctions are often caused by a mixture of psychological and organic factors, treatment strategies combining pharmacological options and sex therapy are advocated.

Differentiating antidepressants of the future: Efficacy and safety

There have been significant advances in the treatment of depression since the serendipitous discovery that modulating monoaminergic neurotransmission may be a pathological underpinning of the disease. Despite these advances, particularly over the last 15years with the introduction of selective serotonin and/or norepinephrine reuptake inhibitors (SNRI), there still remain multiple unmet clinical needs that would represent substantial improvements to current treatment regimens. In terms of efficacy there have been improvements in the percentage of patients achieving remission but this can still be dramatically improved and, in fact, issues still remain with relapse. Furthermore, advances are still required in terms of improving the onset of efficacy as well as addressing the large proportion of patients who remain treatment resistant. While this is not well understood, collective research in the area suggests the disease is heterogeneous in terms of the multiple parameters related to etiology, pathology and response to pharmacological agents. In addition to efficacy further therapeutic advances will also need to address such issues as cognitive impairment, pain, sexual dysfunction, nausea and emesis, weight gain and potential cardiovascular effects. With these unmet needs in mind, the next generation of antidepressants will need to differentiate themselves from the current array of therapeutics for depression. There are multiple strategies for addressing unmet needs that are currently being investigated. These range from combination monoaminergic approaches to subtype selective agents to novel targets that include mechanisms to modulate neuropeptides and excitatory amino acids (EAA). This review will discuss the many facets of differentiation and potential strategies for the development of novel antidepressants.

Antidepressant‐Induced Inhibition of Genital Vascular Responses Is Reversed by Vardenafil in Female Rabbits

INTRODUCTION

Administration of serotonin reuptake inhibitors (SRI) or serotonin and norepinephrine reuptake inhibitors (SNRI) relieves depressive symptoms but may cause sexual dysfunction in women and men.

AIM

The aim of the present study was to evaluate the effects of the phosphodiesterase type 5 (PDE5) inhibitor, vardenafil, on inhibition of genital vascular responses (GVR) induced by SRI or SNRI administration in female rabbits.

METHODS

Vaginal and clitoral vasodilatory responses to pelvic nerve electrical stimulation were measured by laser Doppler flow needle probes.

RESULTS

GVR were significantly potentiated by vardenafil even at the low dose of 0.1 mg/kg, in clitoris and vagina (181 +/- 22% and 180 +/- 31% of control, in vagina and clitoris, respectively, at 8 Hz). The selective SRI, paroxetine (5 mg/kg), significantly inhibited GVR in female rabbits (54 +/- 5% and 48 +/- 6% of control). GVR were also significantly inhibited by the SNRIs, venlafaxine (5 mg/kg) (57 +/- 3% and 32 +/- 11%) and duloxetine (1 mg/kg) (40 +/- 7% and 28 +/- 5%). Treatment with vardenafil (0.1 and 0.3 mg/kg) completely reversed the inhibition of GVR induced by paroxetine, venlafaxine, or duloxetine.

CONCLUSIONS

Potentiation of the nitric oxide (NO) pathway by vardenafil improves vascular sexual responses in female rabbits and overcomes the inhibitory effects of acutely administered antidepressants on GVR, irrespective of the underlying pathophysiologic mechanism, i.e., disruption of the NO pathway or enhancement of alpha-adrenergic mechanisms. PDE5 inhibition may represent a reasonable approach to treat SRI- or SRNI-induced female sexual dysfunction, in particular, arousal disorders.

Sexuality in women with epilepsy

Most women with epilepsy maintain normal reproductive cycles and sexual lives. However, a significant minority, approximately 20-30%, have some degree of sexual dysfunction, including problems with seizure exacerbation, libido, arousal, and orgasm. Fluctuating hormone levels may contribute to an array of reproductive cycling abnormalities. With regard to sexual dysfunction, there is some evidence of reduced genital blood flow in women with temporal lobe epilepsy. Other studies suggest that psychosocial factors, such as depression, feeling stigmatized, and being anxious about having seizures during sex, may contribute to the higher rates of sexual dysfunction in this patient population. Some antiepileptic drugs may adversely affect normal reproductive cycling and sexual function, particularly drugs that increase serotonergic transmission. Conversely, resective epilepsy surgery has been shown to restore sexual function. Treatments for sexual dysfunction include testosterone replacement, although transdermal testosterone replacement is not yet approved by the Food and Drug Administration for women. Given the possibility that women with epilepsy may experience inadequate vasocongestion during arousal, sildenafil may have a useful role, though it has not proved effective for women in general. This review focuses on potential sexual problems that are faced by women with epilepsy, with the suggestion that proper treatment may alleviate these problems.

Vardenafil enhances clitoral and vaginal blood flow responses to pelvic nerve stimulation in female dogs

The relaxation of the smooth muscle in the vagina and clitoris and the increase of blood flow into these organs is thought to be essential in the female sexual response. Vardenafil is a type 5 phosphodiesterase (PDE5) inhibitor that potentiates the nitric oxide (NO)/cGMP pathway facilitating penile smooth muscle relaxation and improving penile erection in men. Although the potentiation of the NO/cGMP pathway through PDE5 inhibitors can clearly enhance blood flow into the penis and is used in the therapy of male sexual dysfunction, there is controversy about the efficacy of these agents in improving female sexual function. The aim of this work was to evaluate the effects of vardenafil on the increase of blood flow into the vagina and clitoris induced by pelvic nerve electrical stimulation (PNES) in a female dog model. Application of PNES produced consistent and frequency-related increased blood flow into the vagina and clitoris of anesthetized female dogs. The magnitude and duration of the blood flow responses to PNES were variable among the different animals but remained stable over time within the same animal. The intravenous administration of vardenafil (1 mg/kg) significantly potentiated the increases in blood flow produced by PNES into the vagina (381.4 and 206.2% of control response at 5 and 10 Hz, respectively, P<0.01, n=6) and clitoris (379.4 and 238.5% of control response at 5 and 10 Hz, respectively, P<0.01, n=6) 20 min after administration. The significant enhancement of PNES-induced responses was maintained 50 min (224.5 and 181.0%, P<0.01 in vagina; 294.8 and 258.9%, P<0.05 in clitoris) and 80 min after vardenafil administration (209.5 and 156.9%, P<0.05 in vagina; 268.9 and 194.9%, P<0.05 in clitoris). Here we present a feasible model for research into female sexual function. Our results show that vardenafil effectively potentiates the blood flow responses to PNES in the genitalia of female dogs. These results emphasize the role of the NO/cGMP pathway in the local vasodilatory response in female sexual organs and provide a rationale for testing PDE5 inhibitors, such as vardenafil, as a treatment for certain forms of female sexual dysfunction.

Vardenafil reverses erectile dysfunction induced by paroxetine in rats

Selective serotonin reuptake inhibitors (SSRIs) are associated with a high incidence of impotence. Paroxetine is an extensively used SSRI that has been shown to impair erectile function in patients, to induce erectile dysfunction and to inhibit nitric oxide synthase (NOS) activity and NO production in animal models. NO is a key mediator of penile erection. Vardenafil is a type 5 phosphodiesterase inhibitor that potentiates NO-mediated responses in isolated trabecular smooth muscle and penile erection in men in clinical trials. The aim of this study was to evaluate the effects of vardenafil on the impairment of erectile responses produced by paroxetine in the rat model. Application of cavernosal nerve electrical stimulation (CNES) produced frequency-related intracavernosal pressure (ICP) increases, which were inhibited by the NOS inhibitor N(G)-nitro-L-arginine (0.3 mg/kg) and potentiated by vardenafil (0.3 mg/kg). Acute paroxetine treatment (10 mg/kg) significantly reduced ICP-responses to CNES. This inhibition was completely reversed by vardenafil (0.3 mg/kg) administration. The results show that the erectile dysfunction induced by paroxetine in rats can be effectively treated with vardenafil, suggesting that the use of this compound could be a reasonable therapeutic approach to treating erectile dysfunction associated with SSRI administration.

Neurochemical aspects of the sexual response cycle

What drives the human sexual response cycle? The human sexual response cycle is a highly complex phenomenon that encompasses many transmitters and transmitter systems centrally and peripherally. The endocrine system is also intricately involved in the brain and in the periphery organs. Integration of these systems is a function of the nervous system that ultimately produces a vast array of cognitive, emotional, physiological, and behavioral responses. Therefore, it is not surprising that a disturbance in even a single system will lead to dysfunction in one or more phases of the sexual response cycle. This article highlights the complex roles the aminergic system plays along with key hormones that are equally involved. The article also points out how rudimentary and fragmented our knowledge is in this field and how few controlled studies are available. The potential for development of specific agents that target selective sexual dysfunctions is exemplified in sildenafil, the first such agent ever to be brought to market.

Selective phosphodiesterase type-5 inhibitor treatment of serotonergic reuptake inhibitor antidepressant-associated sexual dysfunction: a review of diagnosis, treatment, and relevance

Sexual dysfunction related to antidepressants, particularly serotonin reuptake inhibitors is a major cause of premature treatment discontinuation. This places patients at increased risk for recurrence, relapse, chronicity, and mortality (eg, suicide). The clinical assessment requires a comprehensive evaluation of sexual function, including libido, arousal, orgasm, and resolution prior to affective disorder, disturbances associated with the emergence of depression, and changes or dysfunctions associated with antidepressant treatment. Other factors to be included for evaluating sexual dysfunction include inquiry for concurrent medical conditions, somatic treatments, lifestyle risk factors, and response to antidepressants. Current treatment approaches to antidepressant-associated sexual dysfunction have relied on open-label reports, literature reviews, and clinical wisdom. Without double-blind, placebo-controlled studies to support them, too much non-evidence-based treatment may be offered to patients. Advances into nonadrenergic-noncholinergic novel signal transduction, specifically phosphodiesterase type-5 inhibitors, offer new opportunities for developing evidence-based treatments for this side effect and improving depression disease management outcomes.

Female sexual dysfunction in postmenopausal women: systematic review of placebo-controlled trials

OBJECTIVE

This systematic review includes all randomized and placebo-controlled trials (RCTs) of treatment for female sexual dysfunction (FSD) in postmenopausal women published since 1990.

STUDY DESIGN

Electronic database and manual bibliography searches were conducted to identify all relevant publications.

RESULTS

Only six RCTs have been done to assess the effects of different therapies on sexual function in postmenopausal women: one with sildenafil citrate (Viagra), three with hormone replacement therapy, and two with tibolone.

CONCLUSIONS

In women with FSD, many treatments that are used in practice are not supported by adequate evidence. Although an improvement of sexual function was reported with tibolone and the combination of estrogen-androgen therapy, it still remains unclear which groups of postmenopausal women with FSD would benefit most from these therapies. The adverse effects of testosterone replacement therapy should be assessed against the effects of placebo in RCTs with larger sample sizes and longer duration.

The enhancement of vaginal vasocongestion by sildenafil in healthy premenopausal women

OBJECTIVE

This study examined the effect of a single oral dose of sildenafil citrate (Viagra, Pfizer, Inc., New York, NY) on vaginal vasocongestion and subjective sexual arousal in healthy premenopausal women.

METHODS

Twelve women without sexual dysfunction were randomly assigned to receive either a single oral 50 mg dose of sildenafil or matching placebo in a first session and the alternate medication in a second session. Subjective measures of sexual arousal were assessed after participants had been exposed to erotic stimulus conditions. Vaginal vasocongestion was recorded continuously during baseline, neutral, and erotic stimulus conditions. At the end of each session, subjects were also asked to specify which treatment they suspected they had received.

RESULTS

Significant increases in vaginal vasocongestion were found with sildenafil treatment compared with placebo. There were no differences between treatments on subjective sexual arousal experience. Analyses by suspected treatment received found that significantly stronger sexual arousal and vaginal wetness were reported for the treatment that was believed to be sildenafil vs. the treatment that was believed to be placebo. The suspected treatment sequence was incorrect for half of the women. Sildenafil was well tolerated, with no evidence of significant adverse events.

CONCLUSIONS

Sildenafil was found to be effective in enhancing vaginal engorgement during erotic stimulus conditions in healthy women without sexual dysfunction but was not associated with an effect on subjective sexual arousal.

SSRI sexual dysfunction: a female perspective

Women experience two to three times the rate of depression that men do. Selective serotonin reuptake inhibitors (SSRIs) are prescribed for many conditions other than depression, such as anxiety disorders, premenstrual dysphoric disorder, pain syndromes, impulse control disorders, and personality disorders, some of which are more common in women. Increasing awareness of sexual side effects has tempered the initial enthusiasm with which SSRIs were greeted. Men taking SSRIs report higher rates of sexual side effects than women taking them, however, women seem to experience more severe sexual dysfunction. In this article, we discuss the epidemiology of sexual dysfunction and describe treatments with sildenafil.

Palliative care in patients with multiple sclerosis

Multiple Sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) and can be characterized by acute exacerbations or gradual worsening of neurological function and disability. The course of the disease is highly variable and unpredictable, however, there are short and long-term favorable and unfavorable predictive factors, which may provide some information about the future pattern of the disease. Palliative care in MS is directed at symptom management, psychosocial support, and rehabilitation. The goal in palliative care is to achieve a high quality of life. The disease modifying agents, interferon beta, Glatiramer acetate and Mitoxantrone are the mainstay of treatment in MS. Symptomatic relief and counseling of patients with MS have a strong impact on quality of life.

Sildenafil inhibits agonist-evoked rat uterine contractility: influence of guanylyl cyclase inhibition

Sildenafil shows a potent relaxant effect on corpus cavernosum smooth muscles by prolonging cyclic guanosine monophosphate (cGMP) actions. We investigated whether this inhibitory effect of sildenafil was also displayed on the uterine musculature. Isolated uteri of non-pregnant rats were used to measure the possible sildenafil-induced inhibition of contractions evoked by various oxytocic agents, viz., prostaglandin E2, oxytocin and acetylcholine. The relation of these effects to sildenafil action on cGMP was also examined, using methylene blue as a guanylyl cyclase inhibitor. Sildenafil (30 and 100 nM) was found to shift to the right the non-cumulative concentration-response curves of the test agonists in a concentration-dependent manner. The shift was accompanied by a reduction in the maximal response of the tissue to all uterine stimulants selected. Sildenafil also elicited a marked concentration-dependent increase in EC25 of prostaglandin E2, oxytocin and acetylcholine, as compared to their respective control values. Preincubation of the uterine strip with methylene blue (10 microM) reduced the inhibitory effects of sildenafil on oxytocin- and acetylcholine-evoked contractions, at submaximal concentrations of each agonist. The results suggest that sildenafil inhibits the uterotonic potentials of various oxytocic agents and that this effect could be probably related to the drug's action on cGMP.

The impact of the new sexual pharmaceuticals on sex therapy

Since the March 27, 1998 introduction of sildenafil, opportunities for sex therapists have expanded, primarily in three ways: 1) public education, 2) colleague education, and 3) treatment. Primary care physicians and urologists learned that incorporating sex therapy techniques improved the effectiveness of sildenafil; furthermore, sex therapists discovered that integrating adjunctive use of sildenafil with sex therapy accelerated the therapy process and improved outcome. As new pharmaceuticals are developed and approved for men and women, opportunities for medical and nonmedical sex therapists will only increase. In fact, sex therapists are playing an increasingly important consultative role to industry in the research and development of new sexual pharmaceuticals. However, optimism for nonphysician sex therapists is tempered by recognition of the continuing trend toward medicalization of sexual dysfunction.

Managing treatment-emergent sexual dysfunction associated with serotonergic antidepressants: before and after sildenafil

Sexual dysfunction is a common and troublesome side effect associated with selective serotonin reuptake inhibitors and other antidepressants that reportedly occurs in 40%-70% of patients prescribed selective serotonin reuptake inhibitors. Management of this iatrogenic condition has relied on "clinical wisdom" derived over decades primarily from open-label, non-placebo-controlled, selected case and literature review studies. Management approaches fall into four broad categories: 1) antidote, 2) avoidance, 3) augmentation/switching, and 4) adaptation. Until the development of sildenafil (Viagra), none of the existing managements demonstrated clear efficacy in systematic, double-blind, placebo-controlled trials. Renewed interest in treatment-associated sexual dysfunction emerged because of advances in our knowledge of the biological mechanisms of sexual functioning, awareness that sexual dysfunction compromises patient adherence to treatment, and an improved focus on improving disease management outcomes of depression. Recent placebo-controlled studies provide evidence for questioning the effectiveness of earlier approaches to the management of sexual dysfunction side effects, and suggest improved treatment options with sildenafil. Effective management of treatment-emergent sexual dysfunction is a medical necessity in order to prevent relapse and recurrence of serious disorders such as major depression, which are highly treatment responsive but frequently compromised by medication noncompliance due to side effects such as sexual dysfunction.

Phosphodiesterase 5 inhibitors and nitrergic transmission-from zaprinast to sildenafil

Phosphodiesterase 5 terminates the cellular actions of the second messenger molecule cyclic GMP; inhibitors of phosphodiesterase 5 will therefore increase and prolong the actions of endogenous substances that signal via the cyclic GMP pathway, including nitric oxide released as a neurotransmitter from nitrergic nerves. To date, the most widely used phosphodiesterase 5 inhibitors, zaprinast and sildenafil, have proved vital in the elucidation of the widespread role of cyclic GMP in nitrergic transmission and, specifically in the case of sildenafil, have provided a major breakthrough in the treatment of erectile dysfunction in men. Although still a matter of debate, early evidence indicates that sildenafil may also be of benefit in some forms of sexual dysfunction in women. The remarkable clinical success of sildenafil has prompted the search for further novel phosphodiesterase 5 inhibitors which might be used to enhance nitrergic function in other disease states.

Sildenafil citrate: a therapeutic update

BACKGROUND

Since its approval by the US Food and Drug Administration in March 1998, sildenafil citrate has been used by millions of men for the treatment of erectile dysfunction. Recent studies and consensus reports have expanded our understanding of its efficacy, safety, contraindications, and drug interactions.

OBJECTIVE

This paper reviews recent studies of the efficacy of sildenafil, its adverse effects and drug interactions, and socioeconomic factors involved in its use, with a focus on specific patient populations (prostate cancer, diabetes mellitus, ischemic heart disease, spinal cord injuries, neurologic disorders).

METHODS

Clinical studies, case reports, and commentaries and editorials concerning sildenafil published in the international literature between January 1999 and August 2000 were identified through searches of MEDLINE, PREMEDLINE, and International Pharmaceutical Abstracts, using the terms sildenafil, Viagra, and erectile dysfunction.

RESULTS

Sildenafil has demonstrated effectiveness in men with erectile dysfunction associated with prostatectomy, radiation therapy, diabetes mellitus, certain neurologic disorders, and drug therapy (eg, selective serotonin reuptake inhibitors [SSRIs]). It has not been as effective in women with sexual dysfunction, with the exception of SSRI-associated sexual dysfunction. Some disorders unrelated to sexual dysfunction (eg, esophageal motility dysfunction) may also respond to sildenafil. In the general population, sildenafil is considered to have an acceptable tolerability profile; however, patients with moderate to severe cardiovascular disease or those taking nitrate therapy are at increased risk for potentially serious cardiovascular adverse effects with sildenafil therapy. In addition, patients taking drugs that inhibit the cytochrome P450 3A4 isozyme, which metabolizes sildenafil, may experience increased drug concentrations and possible toxicity from normal doses of sildenafil.

CONCLUSIONS

Sildenafil is an effective first-line therapy for erectile dysfunction in men. The decision to prescribe this agent should include such considerations as the cost-risk-benefit balance, patient access, drug distribution pathways, and prescription drug coverage.

Evidence that serotonin affects female sexual functioning via peripheral mechanisms

A review of the literature indicates that serotonin is active in several peripheral mechanisms that are likely to affect female sexual functioning. Serotonin has been found in several regions of the female genital tract in both animals and humans. In the central nervous system (CNS), serotonin acts primarily as a neurotransmitter, but in the periphery, serotonin acts primarily as a vasoconstrictor and vasodilator. Since, in the periphery, the principal component of sexual arousal is vasocongestion of the genital tissue, it is likely that serotonin participates in producing normal sexual arousal. In addition, serotonin administration produces contraction of the smooth muscles of the genito-urinary system and is found in nerves innervating the sexual organs. Taken together, this evidence suggests that peripheral serotonergic activity may be involved in the normal sexual response cycle. In addition, exogenous substances that alter serotonin activity, such as selective serotonin uptake inhibitors (SSRIs) and the atypical antipsychotics, can produce sexual dysfunction. It is possible that sexual side effects seen with these drugs may result, at least in part, from their action on peripheral mechanisms.

Sildenafil citrate on nitrergic transmission in anococcygeus muscles from the urogenital system of male and female mice

The effects of sildenafil on nitrergic relaxations were compared in anococcygeus muscles from male and female mice. In muscles from both sexes, sildenafil (10-300 nM) produced a weak, direct relaxation of carbachol-induced tone, and increased both the amplitude and duration of nitrergic relaxations. The most marked effect was on nitrergic duration (300-400% increase with 300 nM sildenafil); no differences in potency were observed between male (EC(50), 30 nM) and female (EC(50), 25 nM). The rate of onset for potentiation of nitrergic duration was similar in both sexes; but, on washout, the effects of sildenafil declined more slowly in the male muscle. Relaxations to both nitric oxide (NO) and sodium nitroprusside were also increased in amplitude and duration by 50 nM sildenafil, while those to forskolin and papaverine were unaffected. The results demonstrate that sildenafil causes a similar, potent and selective potentiation of nitrergic transmission in urogenital smooth muscle from both male and female mice.

Should patients be given an initial low test dose of sildenafil?

Sildenafil is highly effective for treating erectile dysfunction (ED). However, its use has been associated with serious adverse events including myocardial infarctions and strokes, and 130 verifiable plus 112 unverified deaths reported to the US Food and Drug Administration during the 8 months after sildenafil was introduced in the US, and 522 reported deaths during the 13.5 months after its introduction. Moreover, some events have occurred in men taking their first dose of the agent, suggesting that sildenafil, like some drugs that affect blood pressure, may provoke a first-dose reaction. This possibility warrants extra caution to be used when initiating treatment with sildenafil. Such caution is not currently provided by the current dosage guidelines that, for example, recommend the use of sildenafil 50 mg initially for most men between the ages of 18 and 65 years, despite wide differences in bodyweight, age, drug metabolism, health status and usage of other medications. It can be difficult to identify the patient who may be unusually sensitive to the effects of sildenafil. Exercise stress tests have been recommended, but serious adverse events have occurred in men with normal stress tests following the ingestion of sildenafil. Blood pressure monitoring following sildenafil administration will not prevent a serious adverse drug event already in progress. This article discusses the advantages and disadvantages of initiating treatment with a low test dose of sildenafil, performed at home or in the doctor's office. The advantages of this approach include: (i) identifying patients who are highly sensitive to the effects of sildenafil and who may need no higher dose; (ii) minimising adverse effects such as flushing and dizziness that often frighten patients and may affect adherence; (iii) avoidance of major adverse events; and (iv) reassuring patients with ED who remain wary about trying sildenafil therapy.

Sexual side effects of antidepressant drugs

Sexual functioning often suffers during depression, although depressed people continue to value sex. Many popular antidepressants further impair sexual functioning, with highly serotonergic agents affecting orgasm and libido prominently. This paper addresses clinical assessment of sexual side effects from antidepressant drugs and reviews treatment strategies, including purported antidotes. We pay particular attention to sildenafil, on which there are impressive data and ongoing controlled studies.