Management Strategies for Antipsychotic-Related Sexual Dysfunction: A Clinical Approach

Antipsychotic medication can be often associated with sexual dysfunction (SD). Given its intimate nature, treatment emergent sexual dysfunction (TESD) remains underestimated in clinical practice. However, psychotic patients consider sexual issues as important as first rank psychotic symptoms, and their disenchantment with TESD can lead to important patient distress and treatment drop-out. In this paper, we detail some management strategies for TESD from a clinical perspective, ranging from prevention (carefully choosing an antipsychotic with a low rate of TESD) to possible pharmacological interventions aimed at improving patients’ tolerability when TESD is present. The suggested recommendations include the following: prescribing either aripiprazole or another dopaminergic agonist as a first option antipsychotic or switching to it whenever possible. Whenever this is not possible, adjunctive treatment with aripiprazole seems to also be beneficial for reducing TESD. Some antipsychotics, like olanzapine, quetiapine, or ziprasidone, have less impact on sexual function than others, so they are an optimal second choice. Finally, a variety of useful strategies (such as the addition of sildenafil) are also described where the previous ones cannot be applied, although they may not yield as optimal results.

Ever since the first reports of chlorpromazine and thioridazine causing orgasmic and erectile dysfunction were published [15,16], the knowledge of treatment emergent sexual dysfunction (TESD) and its underlying mechanisms of action has increased greatly. Human sexuality is affected by a variety of neurogenic, psychogenic, vascular, and hormonal factors [17], and the action of antipsychotics may unbalance some of these mechanisms [18]. For example, dopamine facilitates sexual function through the mesolimbic system [19,20], so strict anti-dopaminergic antipsychotics can obstruct this process, but partial dopaminergic agonists such as aripiprazole and cariprazine may not. On the other hand, serotonin inhibits sexual desire [21][22][23][24], likely through postsynaptic 5HT2 receptors, which are often When analyzing SD incidence rates by antipsychotic in a recent meta-analysis (Table 1), it becomes clear that their different mechanisms of action may contribute to separate profiles of adverse effects and how they affect each sexual dimension [61][62][63][64]. However, prevalence of SD in Table 1 does not directly correlate to the incidence rates of TESD by each antipsychotic, because of the influence of several confounding factors (i.e., concomitant medication) [65]. Table 1. Meta-analysis of the prevalence of sexual dysfunction (SD) in patients taking antipsychotics (APS) [61].

Antipsychotic
Prevalence Given the wide array of APS available and their potential for TESD, we aimed in this paper to gather and update relevant information about possible management strategies for this issue that can be considered effective enough without compromising the antipsychotic effect.

Methodology
We performed a review of TESD with antipsychotics and its possible management strategies. PRISMA guidelines were followed when possible ( Figure 1). There was no specific time-delimitation, but priority was given to literature reviews and articles that had been published most recently, with special attention given to articles that had been subjected to peer review. PubMed and Cochrane were the databases used. The term "antipsychotic" was used along with Boolean operator "AND" in combination with several terms: "sexual dysfunction", "erectile dysfunction", "sexual function*" (to allow for both "function" and "functioning"), "desire", "orgasm", and "anorgasmia".
We excluded articles that focused on SD as a general entity rather than as a consequence of treatment with APS, as well as those articles with a broader scope on antipsychotics various side effects that did not focus on sexual function. We also excluded most articles that heavily focused only on metabolic alterations (primarily, hyperprolactinemia or lack thereof) because of antipsychotic treatment, instead of the clinical relevance of TESD. We considered primarily articles written in English, Spanish, Portuguese, or French, although at least one key article written in Dutch was considered for inclusion.
Initially, 1242 relevant results were found. After applying exclusion criteria via abstract screening, 186 relevant results remained; after full manual screening, they were reduced to 178, finding 15 more relevant results through cross-referencing. Upon manual screening and categorizing, these results included (1) those that acknowledged the prevalence and clinical relevance of the phenomenon of antipsychotic TESD, and (2) those that focused on clinical management strategies for TESD. cific time-delimitation, but priority was given to literature reviews and articles that had been published most recently, with special attention given to articles that had been subjected to peer review. PubMed and Cochrane were the databases used. The term "antipsychotic" was used along with Boolean operator "AND" in combination with several terms: "sexual dysfunction", "erectile dysfunction", "sexual function*" (to allow for both "function" and "functioning"), "desire", "orgasm", and "anorgasmia".  The results described under "(1)" were mainly used for Section 1 of this paper. The results on "(1)" added up to a total of 45 articles, including 15 transversal and crosssectional studies, 11 observational studies, and a total of 19 reviews (of which 1 of them was a meta-analysis). Several of these articles were also used on other sections of the paper to provide background, as some of them are antipsychotic-specific.
The results described under "(2)" are included in Section 3 of this paper. There were 121 articles, including 25 reviews (of which 4 were systematic reviews or meta-analyses), 21 experimental studies, 44 observational studies, and 31 papers featuring case series or case reports. The Zotero reference management tool was used to build a database of all the considered articles.

Results
When dealing with TESD, it is practical to be mindful of a three-step sequence: (1) Preventing TESD in the susceptible population. (2) Conducting routine checks for TESD in sexually active patients who are prescribed APS. (3) Performing clinical interventions when TESD is a problem for the patient or poses a risk for treatment drop-out.
Risperidone has been associated with other problems in addition to regular sexual dysfunction, like retrograde ejaculation and urinary dysfunctions [90][91][92][93][94]; anejaculation [95,96]; and, on rare occasions, hypersexuality [97,98]. Part of this SD could be related to high levels of blood prolactin [84,99], resulting in complex hormone regulations that decrease testosterone [100]. Some studies question prolactin levels as the sole mechanism of SD in risperidone [34,65,83,101], and it is likely that a blockade of 5HT2A and 5HT2C receptors at the prefrontal cortex may be responsible too [34,102,103]. Nonetheless, hyperprolactinemia also causes a variety of adverse effects and pathologies that go beyond sexual dysfunction, especially in the long-term [1,60].
Paliperidone, a metabolite of risperidone, has also been linked to hyperprolactinemia [104] and sexual dysfunction [105,106], with similar mechanisms involved. Therefore, hyperprolactinemic APS such as risperidone, paliperidone, amisulpride, and classical antipsychotics are not an appropriate first option if we wish to keep sexual function preserved in psychotic patients [1,65]. In turn, the other atypical antipsychotics fare slightly better in comparison [70].
Clozapine's weaker blockade of D2 dopaminergic receptors in the mesostriatum is supposed to have a lesser incidence of orgasm dysfunction and erectile dysfunction when compared with typical neuroleptics [107,108], although not by a wide margin [109]. A case of hypersexual behavior with clozapine has been reported [110], although it is not a common adverse effect.
Ziprasidone, because of its mechanism of action (5-HT2 receptor antagonism facilitating dopamine release in the cortex), would theoretically improve orgasmic and erectile function, as suggested by some case reports concerning spontaneous ejaculation and priapism [111,112]. However, there is only one study researching its effect on sexual function to our knowledge. In a small (n = 15), 3-month observational study, patients who were antipsychotic-naïve commenced treatment with ziprasidone, preserving sexual functioning across all sexual dimensions, and even slightly improving the minor sexual dysfunction found in baseline [113]. Although promising, these results need further confirmation. Olanzapine causes less extrapyramidal symptoms [76], less hyperprolactinemia [79,80,114], and less SD than haloperidol [115] and risperidone [68,71,81,116]. Orgasm, ejaculation, and arousal are usually less affected by olanzapine than by risperidone [78,81], as also suggested by some case reports of spontaneous ejaculation [117] and priapism [118]. However, some studies consider these differences to be relatively minor or nonexistent [66,114], especially when olanzapine doses reach 15-20 mg/day [62,82]. These results suggest that olanzapine causes a dose-dependent mild to moderate hyperprolactinemia.
Quetiapine, on the other hand, does not significantly increase prolactin levels [82]. There has been lower reported incidence of SD with quetiapine when compared with typical neuroleptics, and some atypical (risperidone and olanzapine) [72,83,84,119]. With one exception [72], most of the studies agree that, when dosing below 400 mg/day, sexual function is mostly preserved [62,82,84], but when dosing at around 500 mg/day and above, SD may appear with a severity in proportion to dosage [66,120], although usually less so than the previously mentioned antipsychotics [53,121]. Quetiapine has also been described as particularly helpful in preserving sexual arousal [52,66,72].
Aripiprazole, a partial dopamine receptors agonist, as well as its partial 5HT1A agonism and 5HT2A antagonism, has been correlated to no actual increase in prolactin levels [88,119,122]. In fact, when used in combination with another antipsychotic, it has been observed to lower already increased prolactin levels [123]. When dosing at around 15 mg/day, this results in no SD at all [53,87,88], or SD of mild intensity, usually being tolerable for the patient. One study concludes that aripiprazole causes less SD than risperidone, olanzapine, or quetiapine [119]. However, while aripiprazole remains the best option among the researched evidence when trying to prevent TESD [70], several cases of hypersexual behavior have been reported to be directly caused by this drug [123][124][125][126][127], which apparently can manifest at any dose, but seem to be more frequent when dosing above 20 mg/day [125]. Cariprazine, which is another dopamine partial agonist like aripiprazole that does not produce hyperprolactinemia [128,129], still has no published data regarding its effect on sexual function. Although it could be considered similar to aripiprazole, specific studies are needed.

Detection and Exploration of TESD
Psychotic patients are a very heterogeneous group in terms of clinical evolutions, treatment response, and sexual activity, so being mindful of this issue and its possible repercussions on adherence becomes difficult at times for both the clinician [46] and the patient. For example, uncompensated patients with acute symptomatology that require hospitalization do not share the same concern for their sexuality as fully stabilized chronic patients do [130][131][132]; clinicians treating the former may overlook this issue at first while attempting to treat psychotic symptomatology.
That is why, when SD shows up, it is crucial to examine how the patient accepts this adverse effect and how it influences their quality of life and overall functionality. The spontaneous communication rate of SD from patients is low [1,53,133], so medical staff should routinely check with the patients to detect if TESD exists by asking clear questions, such as "How has your sexual life been since you started taking the medication?" and "Have you noticed any change that worries you?" This issue should always be approached in a neutral manner, expressing concern about the patient's wellbeing and informing them about the potential sexual side effects of APS medication [59]. Gathering a full sexual medical history is useful to thoroughly understand the onset of the first SD symptoms, SD severity, the impact of SD on the sexual lives of the patient and their partner, and the influence of SD on the patient's quality of life [134]. This thorough evaluation would also help to determine whether SD is in fact a consequence of antipsychotic treatment or is caused by other factors such as comorbidities, substance abuse, or other prescribed medication [3].
To better quantify TESD and measure its degree of acceptance by the patient, several specific validated scales and structured questionnaires can be of use. As the rate of SD can vary depending on which scale is used [68], a combination of several of them would be best in order to best determine its existence and its intensity, especially when researching this issue [65].

Intervention
Once TESD is identified, if it is poorly tolerated by the patient and risks compromising adherence, it may be possible to intervene depending on the particular clinical symptoms of each case. While sometimes, fully restoring previous sexual function is not achievable, partially alleviating the experienced symptoms can satisfy the patient's expectations without jeopardizing the antipsychotic effect of their treatment. When compared with SD caused by antidepressants, the literature on intervention in TESD caused by APS is scarce, and frequently inconsistent [2,147], although some viable options emerge. Some possible strategies for treating TESD are the following: (1) waiting for spontaneous remission; (2) dose reduction; (3) switching to another APS; and (4) the addition of an antidote (coadjuvant drug). None of these methods is devoid of risks, such as a relapse, so a careful individualized approach is suggested so that patients can make an informed choice.

Waiting for Spontaneous SD Remission
Sometimes, adverse effects subside over time. Spontaneous SD remission has been reported in patients with antidepressant treatment [148]. However, it only has been reported to occur in 5-10% of the subjects and generally after 4 to 6 months of treatment [2]. One study analyzed this possibility with antipsychotics [108], and found that patients treated with clozapine experienced TESD, but it decreased dramatically or completely resolved over the course of 18 weeks. In our Spanish Working Group for the Study of Psychotropic-Related Sexual Dysfunction, this adaptation or tolerance to the adverse effect was also analyzed [149]. We found 6 out of 36 patients (16.7%) with SD caused by risperidone presenting spontaneous improvement after 6 months, and one patient improving after 3 months. These results prove unlikely that spontaneous remission can be expected before this time.
An alternative explanation for SD spontaneously improving over time would be that SD is more directly related to the severity of illness rather than the antipsychotic treatment; thus, after being treated, sexual function would consequently improve.
However, considering the current data, this strategy does not seem to be recommendable. It possibly encourages treatment drop-out, thus deteriorating quality of life and disrupting the patient-physician relationship [2,150].

Dose Reduction
As seen with selective serotonin reuptake inhibitors (SSRIs) [2], dose reduction strategies could work in theory [151,152], as the diverse effects of APS are highly dependent on dosage. An alternative explanation could be that illness severity is related to SD, and as the decision of a lower dosage implies a clinical improvement, psychosis may not impact sexual function as severely as previous higher doses of antipsychotic.
Nevertheless, some authors recommend decreasing the dose as the first step in intervention [153], but this is not always effective [154] and may in fact risk a relapse [1]. Therefore, perhaps only selected patients with relatively mild symptoms or an overall good prognosis may be candidates for this strategy. In a study by our Spanish Working Group, we found that 19 out of 26 patients (73%) treated with risperidone, who presented SD, improved partially or fully when the dose was reduced to 50% [149]. Individual differences play a key part here, and when comparing multiple studies mentioned in Section 3.1, a certain dose of one specific antipsychotic does not always equate to a proportional correlation of SD in all patients. This might suggest that, above a certain threshold dose, patients with APS may develop SD of varying degrees independently of dose increase. This can be seen when comparing the rates of SD caused by olanzapine and risperidone at different doses (Table 3). A strategy similar to dose reduction that has sometimes worked when dealing with TESD caused by antidepressants is the periodic treatment interruption or "weekend holiday" [148], where the patient interrupts treatment for a period of time (24 h prior to intercourse). The usefulness of this strategy is highly dependent on the specific half-life of the drug being used. No studies have been performed with APS regarding this strategy [2,156]. In fact, randomized controlled trials are currently needed to provide evidence for this or any other dose reduction strategies [147,157].
While perhaps useful regarding antidepressant treatment, this strategy is not recommended in Schizophrenia spectrum disorders as it carries significant risks of relapse, and may inadvertently encourage treatment drop-out.

Switching to Another Antipsychotic
In patients who present severe SD who cannot risk reducing treatment doses, or are unwilling to continue treatment because of this cause, switching to another antipsychotic with a lesser SD incidence rate is a viable option [3,153].
There are other switching options to decrease SD, although the evidence for them is not as strong, as most studies have focused on aripiprazole's potential.
A small open label trial points to olanzapine as an option [147], as it had been previously suggested by one case report [129] and an observational study [155].
As for quetiapine, the results are contradictory. Case reports and prospective studies suggest that switching to quetiapine might improve SD in a way that is tolerated by the patient [162,163], with one randomized trial confirming these positive results [84] at a mean dose below 500 mg/day. However, another randomized trial did not show a significant difference in SD improvement [63,147]. Nonetheless, it is still recommended as an option by some authors [1,150,157].
Further less-researched options include ziprasidone, with a 3-month prospective switching study showing improvement in SD [113]. Lurasidone, with a case report showing a decrease in SD when switching from risperidone [90] and a clinical trial showing it was not associated with treatment-related SD versus placebo [164], could be a useful alternative. Nonetheless, hypersexuality has been associated with both lurasidone [165] and ziprasidone [166], so additional research is needed. Unfortunately, a recent clinical trial aimed at knowing the outcome of the antipsychotic switching strategy versus maintaining prior treatment failed to obtain significant results because of a very low level of recruitment [167], probably explained by a reluctance among patients to switch medication and reticence of both staff and patients to talk about sex. Now, there are no studies of switching to cariprazine, which has a mechanism of action similar to aripiprazole, although theoretically, it could be an appropriate alternative [128,168]. Finally, brexpiprazole, a metabolite of aripiprazole, has been shown in clinical trials not to modify prolactin levels [169], and possibly has a good profile on sexual function.

Use of Antidotes or Coadjuvant Treatment
When switching to another antipsychotic is not recommended or there is a potential risk for relapse, the next strategy could be the prescription of another drug or "antidote" to improve TESD in some way. In addition to being the best switching option when dealing with TESD, aripiprazole has been noted to both decrease prolactin levels and improve SD when taken concomitantly with other antipsychotics [1,2,170,171]. This has been observed across populations by several randomized studies [159,172,173] when acting as coadjuvant treatment for a variety of APS with different mechanisms of action, both typical and atypical. Aripiprazole's action as a partial dopaminergic agonist and its role in reversing hyperprolactinemia are probably responsible for improving TESD [2], perhaps through the increase of dopaminergic activity. Although the specific dosage may be individualized according to TESD severity and the other APS prescribed, aripiprazole has been well tolerated as an add-on drug without worsening psychiatric symptoms in any way [159,172].
Aside from aripiprazole, phospodiesterase-5 (PDE-5) inhibitors have been observed to improve erectile dysfunction (ED) caused by APS [1][2][3]134,174,175]. Their mechanism of action targets the nitric oxide inhibition that some APS cause [40,41]. After the first successful case report with sildenafil, suggesting it as an option [176], two small observational studies followed with moderate to good results [177,178]. Despite a small sample (n = 32) and short duration (2 weeks), a randomized placebo-controlled trial confirmed the potential of sildenafil as coadjuvant treatment in TESD [179], as ratified by a Cochrane review [147]. As with aripiprazole, the specific dose probably needs to be individualized for each patient, with some experiencing improvement at 25 mg/day and others at 100 mg/day. Furthermore, a successful case report with tadalafil [180] also inspired another randomized placebocontrolled trial with good results using the ASFQ [181], despite a similarly small sample (n = 15) owing to it being a crossover pilot study. Other PDE-5 inhibitors have also been studied for this purpose, such as vardenafil, with good results [182], as well as lodenafil carbonate [183], which did not render statistical differences when compared with placebo.
Regarding other add-on options, the evidence is not as strong. The coadjuvant use of pro-dopaminergic drugs has also theoretically been proposed as a solution [2,3,184,185], but given the risk of worsening psychiatric symptoms, they are not recommended in this case. The only study we found with these types of drugs for TESD was a small placebocontrolled study with selegiline, which did not seem to improve SD, despite decreasing prolactin levels [186].

Clinical Recommendations
Although there is scarce information, it seems that the incidence of antipsychotic related TESD is deeply underestimated by clinicians. The main reason is that psychiatrists rarely question their patients about their sexual activity, considering it erroneously intrusive; a lack of interest, time, or training in these competencies is also to blame. Antipsychotic treatment is usually necessary for long periods of time or even indefinitely, and SD can compromise adherence [11,12,192], thus worsening the patient's quality of life [106] as well as their partner's, leading to relapses and recurrences. There is a risk of overstating the role of psychosis and delusional disorders provoking TESD. Despite the limited existence of clinical trials and the need for stronger evidence, from a clinical point of view, psychiatrists need a useful and practical approach to obtain appropriate coping strategies. The only way to know the true effect of medication is to properly explore sexual function both before and after starting a treatment with an antipsychotic. At the same time, knowing how relevant sexual aspects are for the patient's quality of life could help us to sooner identify the risk of treatment-dropout due to poor tolerance of SD. Clinicians should monitor the possible changes in sexual function and should select an individualized strategy for the management of TESD that is poorly tolerated by the patient or their partner. Additionally, a rich and healthy sex life can help patients to maintain their bonds and contribute to much-needed socialization skills in psychosis.
Clinicians should be mainly interested in primary prevention and starting a treatment with APS that preserve sexual function should always be the first choice in sexually active patients who want to maintain their previous sexual activity. There is recent evidence that only 3% of psychiatrists routinely evaluate sexual functioning using specific psychometric tests [46], so psychiatrists' interest in their patients' sex life, as well as their specific skills to prevent, detect, and treat TESD, should be encouraged.
Aripiprazole, quetiapine, and ziprasidone, and perhaps olanzapine below 15 mg/day, are some of the better APS to either avoid or alleviate TESD. Risperidone, paliperidone, amisulpride, and typical APS should not be a first choice in patients with an active sex life who do not accept its deterioration. However, in some situations where it is not possible to avoid them, associating aripiprazole seems to be the best option. If prevention is not possible, there are several strategies to manage TESD symptomatology. The literature data reviewed in the present study (albeit scarce) [193], as well as recommendations based on the level of scientific evidence, allow us to recommend different intervention strategies according to the key TESD symptoms following the Scottish Intercollegiate Guidelines Network Grading Review Group [194] (Table 4). Table 4. Clinical recommendations for alleviating TESD based on scientific evidence levels * [194].

Conclusions
The sexual function of psychotic patients must be assessed by the clinician thoroughly and regularly, in order to assess their tolerance to treatment with antipsychotics and avoid possible treatment dropouts. Some well validated scales for doing so are the PRSexDQ, ASFQ, and CSFQ, as they explore all stages of sexual functioning in patients with psychosis. Considering the current results, it seems clear that a subgroup of APS has a greater capacity for producing SD than others. Waiting for spontaneous TESD remission or reducing the antipsychotic dose are suboptimal strategies with little or no evidence and potential risk for psychotic relapse.
Aripiprazole (and perhaps other dopamine partial agonists like brexpiprazole or cariprazine) is the best option to prevent TESD, and it is the first-choice antipsychotic for this issue, in both antipsychotic-naïve patients and in those who have experienced SD as a consequence of treatment with another APS. Moreover, aripiprazole improves TESD and prolactin levels when it is used as coadjuvant treatment with another antipsychotic. Quetiapine or olanzapine (below 15 mg/day) can be useful second options for TESD in monotherapy when not surpassing a certain threshold dose. When switching or adding aripiprazole is not a viable option, PDE-5 inhibitors such as sildenafil, tadalafil, or vardenafil can improve ED in male patients.
Lastly, we should not forget that open communication with our patients about this problem is vital and, therefore, each management strategy needs to be individualized to the needs of each patient. Only if we do this will we be able to humanize treatment and improve patient-clinician relationships while ensuring adherence, quality of life, and the ability to maintain stable and enriching emotional bonds.

Limitations
There is little information compared with antidepressants on the best method of treatment for clinical evidence based TESD [148]. Some APS that are very similar to aripriprazole, like cariprazine or brexpiprazole, do not yet have studies on the subject and recommending them might be speculative. On the other hand, the disease itself may have some influence on the onset of sexual dysfunction and the antipsychotic may not be the only mechanism involved, as well as hyperprolactinemia. More research is needed in this field to obtain better recommendations based on clinical evidence.