Open-label sildenafil treatment of partial and non-responders to double-blind treatment in men with antidepressant-associated sexual dysfunction

Phosphodiesterase inhibitors in psychiatric disorders

RATIONALE

Challenges in drug development for psychiatric disorders have left much room for the introduction of novel treatments with better therapeutic efficacies and indices. As a result, intense research has focused on identifying new targets for developing such pharmacotherapies. One of these targets may be the phosphodiesterase (PDE) class of enzymes, which play important roles in intracellular signaling. Due to their critical roles in cellular pathways, these enzymes affect diverse neurobiological functions from learning and memory formation to neuroinflammation.

OBJECTIVES

In this paper, we reviewed studies on the use of PDE inhibitors (PDEIs) in preclinical models and clinical trials of psychiatric disorders including depression, anxiety, schizophrenia, post-traumatic stress disorder (PTSD), bipolar disorder (BP), sexual dysfunction, and feeding disorders.

RESULTS

PDEIs are able to improve symptoms of psychiatric disorders in preclinical models through activating the cAMP-PKA-CREB and cGMP-PKG pathways, attenuating neuroinflammation and oxidative stress, and stimulating neural plasticity. The most promising therapeutic candidates to emerge from these preclinical studies are PDE2 and PDE4 inhibitors for depression and anxiety and PDE1 and PDE10 inhibitors for schizophrenia. Furthermore, PDE3 and 4 inhibitors have shown promising results in clinical trials in patients with depression and schizophrenia.

CONCLUSIONS

Larger and better designed clinical studies of PDEIs in schizophrenia, depression, and anxiety are warranted to facilitate their translation into the clinic. Regarding the other conditions discussed in this review (most notably PTSD and BP), better characterization of the effects of PDEIs in preclinical models is required before clinical studies.

Pharmaceutical management of sexual dysfunction in men on antidepressant therapy

INTRODUCTION

Sexual dysfunction (SD) and depression have a bidirectional relationship. The rising prescription of antidepressants, especially those with a serotonergic effect, is associated with increased SD. Sexual dysfunction reduces compliance and increases risk of recurrence of depressive episodes. Various strategies have been studied to manage antidepressant-induced SD.

AREAS COVERED

This review covers the identification of symptoms of antidepressant-induced SD, prevalence of symptoms in association with commonly used antidepressants, and the main lines of management, with a focus on pharmacological strategies.

EXPERT OPINION

The management of antidepressant-induced SD aims to reduce the unwanted sexual adverse effects while maintaining an acceptable control of depressive symptoms. It should implicate a multidisciplinary approach and determination of baseline sexual function and SD risk factors. In spite of several methodological issues, antidepressants can be divided into low- and high-risk categories with regard to the possibility of developing SD. In patients interested in sexual activity, it is recommended to start with low-risk antidepressants. Otherwise, encourage the patient to wait for tolerance and then switch to low-risk. In selected cases, dose reduction or a drug holiday may be applied. The adjunctive use of a PDE5i can help in a significant number of patients. Randomized controlled trials are needed to set high-level evidence-based recommendations.

Phosphodiesterase-5 inhibitors: Shedding new light on the darkness of depression?

BACKGROUND

Phosphodiesterase-5 inhibitors (PDE5Is) are used to treat erectile dysfunction (ED). Recently, the antidepressant-like effect of PDE5Is was demonstrated in animal models of depression. In clinical settings, PDE5Is were studied only for ED associated depression. Hence, there are no studies evaluating the effects of PDE5Is for the treatment of major depressive disorder (MDD) without ED. In this review article, we aimed to discuss the use of PDE5Is in the context of MDD, highlighting the roles of PDE genes in the development of MDD, the potential mechanisms by which PDE5Is can be beneficial for MDD and the potentials and limitations of PDE5Is repurposing to treat MDD.

METHODS

We used PubMed (MEDLINE) database to collect the studies cited in this review. Papers written in English language regardless the year of publication were selected.

RESULTS

A few preclinical studies support the antidepressant-like activity of PDE5Is. Clinical studies in men with ED and depression suggest that PDE5Is improve depressive symptoms. No clinical studies were conducted in subjects suffering from depression without ED. Antidepressant effect of PDE5Is may be explained by multiple mechanisms including inhibition of brain inflammation and modulation of neuroplasticity.

LIMITATIONS

The low number of preclinical and absence of clinical studies to support the antidepressant effect of PDE5Is.

CONCLUSIONS

No clinical trial was conducted to date evaluating PDE5Is in depressed patients without ED. PDE5Is' anti-inflammatory and neuroplasticity mechanisms may justify the potential antidepressant effect of these drugs. Despite this, clinical trials evaluating their efficacy in depressed patients need to be conducted.

Strategies for managing sexual dysfunction induced by antidepressant medication

BACKGROUND

Sexual dysfunction (including altered sexual desire, orgasmic and ejaculatory dysfunction, erectile and other problems) is a relatively common side effect of antidepressant medication. These sexual side effects may compromise a person's lifestyle and result in a lack of compliance with the prescribed antidepressant to the detriment of the person's mental health. A wide range of management strategies are possible to address this problem, including behavioural, psychological and pharmacological approaches.

OBJECTIVES

1. To determine the effectiveness of management strategies for sexual dysfunction caused by antidepressants.2. To determine the adverse effects and acceptability of the different management strategies.

SEARCH METHODS

We searched the Cochrane Depression, Anxiety and Neurosis Group's Specialized Register (CCDANCTR, to 1 January 2013), which includes relevant randomised controlled trials from the following bibliographic databases: The Cochrane Library (all years), EMBASE (1974 to date), MEDLINE (1950 to date) and PsycINFO (1967 to date). Additional searches were carried out by the author team on the same biomedical databases (using terms for 'sexual dysfunction' only) together with CINAHL (1982 to Jan 2012). The reference lists of reports of all included studies were screened.

SELECTION CRITERIA

We included randomised controlled trials that compared management strategies for antidepressant-induced sexual dysfunction versus placebo or any alternative strategy.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data and assessed trial quality. Study authors were contacted for additional information.

MAIN RESULTS

We included 23 trials involving 1886 people in this updated review. Twenty-two of these trials investigated the addition of medication to treat the identified dysfunction, with most agents studied in only single studies. One study investigated switching to an alternative antidepressant.In men, data for the phosphodiesterase inhibitors sildenafil (three studies, 255 participants) and tadalafil (one study, 54 participants) indicated they led to a greater improvement in erectile function than placebo. Combined data from three sildenafil studies found benefit over placebo on International Index of Erectile Function ratings of ability to achieve (MD 1.04, 95% CI 0.65 to 1.44), and maintain erections (MD 1.18, 95% CI 0.78 to 1.59). A single point improvement on these ratings is equivalent to an improvement in frequency from 'sometimes' to 'most times'. Men receiving tadalafil were more likely to report improved erectile function (RR 11.50, 95% CI 3.03 to 43.67). For women it remains uncertain whether sildenafil is more effective than placebo. Unpublished data could reduce this uncertainty.Data from three studies in men and women of bupropion 150 mg twice daily indicate a benefit over placebo on rating scale scores (SMD 1.60, 95% CI 1.40 to 1.81), but response rates in two studies of bupropion 150 mg once daily demonstrated no statistically significant difference in effect (RR 0.62, 95% CI 0.09 to 4.41).Other augmentation strategies failed to demonstrate significant improvements in sexual dysfunction compared with placebo.One trial involving 75 people with sexual dysfunction due to sertraline assessed the effect of changing antidepressant. Switching to nefazodone was significantly less likely to result in the re-emergence of sexual dysfunction than restarting sertraline (RR 0.34, 95% CI 0.19 to 0.60), however, nefazodone is no longer available for clinical use.There is an absence of randomised trials assessing the effects of switching to currently-available antidepressant agents with lower rates of adverse sexual effects, the role of psychological or mechanical interventions, or of techniques such as drug holidays.We identified no data for any of the strategies included in the trials assessed that indicated that they led to a worsening of psychiatric symptoms. However, the relatively small numbers assessed for many of the interventions studied means that the possibility of such an effect cannot confidently be excluded in all cases.Given the small numbers of studies assessing most of the strategies assessed, the presence of any unpublished trials could have substantial effects on estimates of effect. In some cases, only results from particular items or subscales within ratings scales are available. It is likely that this could act to bias estimates of effect obtained, increasing apparent effectiveness.

AUTHORS' CONCLUSIONS

The evidence currently available is rather limited. For men with antidepressant-induced erectile dysfunction, the addition of sildenafil or tadalafil appears to be an effective strategy. For women with antidepressant-induced sexual dysfunction the addition of bupropion at higher doses appears to be the most promising approach studied so far.

Sildenafil, a phosphodiesterase type 5 inhibitor, enhances the activity of two atypical antidepressant drugs, mianserin and tianeptine, in the forced swim test in mice

Sildenafil, a selective phosphodiesterase type 5 inhibitor, has recently been reported to abolish anti-immobility action of antidepressant drugs, i.e., bupropion, venlafaxine and S-citalopram, in the forced swim test in mice. The present study was designed to investigate the influence of sildenafil on the potential of two atypical antidepressants, namely mianserin and tianeptine. Swim sessions were conducted by placing mice in glass cylinders filled with water for 6 min and the duration of the behavioral immobility during the last 4 min of the test was evaluated. Locomotor activity was measured with photoresistor actimeters. To evaluate the potential pharmocokinetic interaction, total brain concentrations of the studied antidepressants were determined by HPLC method. Sildenafil at a dose of 2.5 mg/kg did not affect the activity of mianserin (20 mg/kg) in the forced swim test. Interestingly, at higher doses (5 and 10 mg/kg), sildenafil significantly enhanced the anti-immobility action of mianserin. Likewise, sildenafil (5, 10 and 20 mg/kg) robustly augmented the antidepressant activity of tianeptine (30 mg/kg). Mianserin alone, as well as in a combination with sildenafil at the highest dose, caused a potent reduction in locomotor activity. However, the changes in motor activity did not interfere with the data obtained in the forced swim test. Sildenafil significantly increased the total brain tianeptine concentration. No alteration in mianserin level in the brain after sildenafil co-administration was observed. The present study suggests that sildenafil enhances the activity of mianserin and tianeptine in the forced swim test in mice. The changes in the antidepressant activity of mianserin evoked by sildenafil co-administration were related to pharmacodynamic interaction while the interaction between tianeptine and sildenafil was, at least in part, pharmacokinetic in nature.

Toward a new 'EPOCH': optimising treatment outcomes with phosphodiesterase type 5 inhibitors for erectile dysfunction

Despite the marked adverse impacts of erectile dysfunction (ED) on quality of life and well-being, many patients (and/or their partners) do not seek medical attention for this problem, do not receive treatment or discontinue such treatment even when it has effectively restored erectile responses to sexual stimulation. Phosphodiesterase type 5 (PDE5) inhibitors are considered first-line therapies for men with ED. To help physicians maximise the likelihood of treatment success with these agents, we conducted an English-language PubMed search of articles involving approved PDE5 inhibitors dating from 1 January 1998 (the year in which sildenafil citrate was introduced), through 31 August 2008. In addition to sildenafil, tadalafil and vardenafil, search terms included 'adhere*', 'couple*', 'effect*', 'effic*', 'partner*', 'satisf*', 'succe*' and 'treatment outcome.' Based on our analysis, physician activities to promote favourable treatment outcomes may be captured under the mnemonic 'EPOCH': (i) Evaluating and educating patients and partners to ensure realistic expectations of therapy; (ii) Prescribing a treatment individualised to the couple's lifestyle needs and other preferences; (iii) Optimising treatment outcomes by scheduling follow-up visits with the patient to 'fine-tune' dosages and revisit key educational messages; (iv) Controlling comorbidities via lifestyle counselling, medications and/or referrals and (v) Helping patients and their partners to meet their health and psychosocial needs, potentially referring them to a specialist for other forms of therapy if they are not satisfied with PDE5 inhibitors.

Phosphodiesterase genes and antidepressant treatment response: a review

Depression results in a tremendous burden to individuals suffering from the disorder and to the global health economy. Available pharmacologic treatments for depression target monoamine levels and monoamine receptors. However, delayed onset of effect, partial or inadequate treatment response, and side-effects are significant limitations of current therapies. The search for a better understanding of mechanisms of depression and for new treatment targets has turned attention to intracellular mediators. Phosphodiesterases (PDEs) are enzymes that break down the intracellular second messenger mononucleotides cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Recent data from animal and human studies indicate that PDEs may play a role in depression and in related stress conditions. PDE genes have been linked directly to depression and to other genes associated with psychiatric disorders.