Risk Factors, Incidence, and Outcomes of Neuroleptic Malignant Syndrome on Long-Acting Injectable vs Oral Antipsychotics in a Nationwide Schizophrenia Cohort

A review on side effect management of second-generation antipsychotics to treat schizophrenia: a drug safety perspective

INTRODUCTION

Effective side effects management present a challenge in antipsychotic treatment with second-generation antipsychotics (SGAs). In recent years, most of the commonly used SGAs, except for clozapine, have been shown to differ only slightly in their effectiveness, but considerably regarding perceived side effects, safety profiles, and compatibility to preexisting medical conditions.

AREAS COVERED

The current state of available evidence on side-effect management in SGA treatment of patients with schizophrenia spectrum disorders (SSD) is reviewed. In addition, current guideline recommendations are summarized, highlighting evidence gaps.

EXPERT OPINION

SGA safety and side effects needs to be considered in treatment planning. Shared decision-making assistants (SDMA) can support patients, practitioners and relatives to orient their decisions toward avoiding side effects relevant to patients' adherence. Alongside general measures like psychosocial and psychotherapeutic care, switching to better tolerated SGAs can be considered a relatively safe strategy. By contrast, novel meta-analytical evidence emphasizes that dose reduction of SGAs can statistically increase the risk of relapse and other unfavorable outcomes. Further, depending on the type and severity of SGA-related side effects, specific treatments can be used to alleviate induced side effects (e.g. add-on metformin to reduce weight-gain). Finally, discontinuation should be reserved for acute emergencies.

Identification and treatment of individuals with childhood-onset and early-onset schizophrenia

Approximately 8 % of patients with schizophrenia are diagnosed before age 18, and 18 % experience their first symptoms before age 18. This narrative review explores the management of patients with early-onset schizophrenia (EOS) and childhood-onset schizophrenia (COS) from diagnosis to their transition to adult care settings. Early diagnosis of schizophrenia in children and adolescents is essential for improving outcomes, but delays are common due to overlapping of symptoms with developmental phenomena and other psychiatric conditions, including substance use, and lack of clinicians' awareness. Once diagnosed, antipsychotic treatment is key, with specific second-generation agents generally being preferred due to better tolerability and their broader efficacy evidence-base in youth. Dosing should be carefully individualized, considering age-related differences in drug metabolism and side effect liability. Clinicians must be vigilant in detecting early non-response and consider switching or dose escalation when appropriate. Since early age of illness onset is a consistent risk factor for treatment-resistant schizophrenia (TRS), clinicians need to be competent in diagnosing TRS and using clozapine. Since COS and EOS are associated with cognitive deficits and impaired functioning, psychosocial interventions should be considered to improve overall functioning and quality of life. Good long-term outcomes depend on continuous treatment engagement, and successful transitioning from pediatric to adult care requires careful planning, early preparation, and collaboration between pediatric and adult clinicians. Targeting functional outcomes and quality of life in addition to symptom remission can improve overall patient well-being. Comprehensive evaluations, age-specific assessments, and targeted interventions are needed to address the unique challenges of EOS and COS.

Serious adverse drug events associated with psychotropic treatment of bipolar or schizoaffective disorder: a 17-year follow-up on the LiSIE retrospective cohort study

Introduction

Mood stabilisers and other psychotropic drugs can lead to serious adverse drug events (ADEs). However, the incidence remains unknown. We aimed to (a) determine the incidence of serious ADEs in patients with bipolar or schizoaffective disorders, (b) explore the role of lithium exposure, and (c) describe the aetiology.

Methods

This study is part of the LiSIE (Lithium-Study into Effects and Side Effects) retrospective cohort study. Between 2001 and 2017, patients in the Swedish region of Norrbotten, with a diagnosis of bipolar or schizoaffective disorder, were screened for serious ADEs to psychotropic drugs, having resulted in critical, post-anaesthesia, or intensive care. We determined the incidence rate of serious ADEs/1,000 person-years (PY).

Results

In 1,521 patients, we identified 41 serious ADEs, yielding an incidence rate of 1.9 events per 1,000 PY. The incidence rate ratio (IRR) between ADEs with lithium present and causally implicated and ADEs without lithium exposure was significant at 2.59 (95% CI 1.20-5.51; p = 0.0094). The IRR of ADEs in patients <65 and ≥65 years was significant at 3.36 (95% CI 1.63-6.63; p = 0.0007). The most common ADEs were chronic lithium intoxication, oversedation, and cardiac/blood pressure-related events.

Discussion

Serious ADEs related to treatment of bipolar (BD) or schizoaffective disorder (SZD) were uncommon but not rare. Older individuals were particularly at risk. The risk was higher in individuals exposed to lithium. Serum lithium concentration should always be checked when patients present with new or unclear somatic symptoms. However, severe ADEs also occurred with other mood stabilisers and other psychotropic drugs.

Tolerability and safety outcomes of first-line oral second-generation antipsychotics in patients with schizophrenia

INTRODUCTION

Antipsychotics are the foundation of pharmacologic treatment for schizophrenia. There are many oral antipsychotics available and given that these medications are generally considered comparably efficacious when titrated to an adequate dose, their varied tolerability, and safety profiles become critically important for medication selection.

AREAS COVERED

This paper reviews tolerability and safety considerations for first-line second-generation oral antipsychotics currently approved for the treatment of schizophrenia in the USA. Excluded from consideration are clozapine and non-oral formulations.

EXPERT OPINION

Among antipsychotics, there are many differences in adverse reactions observed in clinical trials, such as variable likelihood to cause sedation vs insomnia, weight gain and abnormalities in glucose/lipid metabolism, hyperprolactinemia, potential for impact on the QT interval, and motoric adverse effects. Additional safety data that can help with medication selection include safety in pregnancy and lactation, and potential for drug-drug interactions. Ultimately, working with patients to personalize treatment by focusing on safety and individual tolerability considerations for various adverse effects can help in building a therapeutic alliance and improving patients' outcomes.

Catatonia-related adverse outcomes after long-acting injectable antipsychotics: Case series

Due to a lack of controlled, prospective trials examining the pathophysiology and treatment of catatonia, current guidelines vary regarding how and when to best use antipsychotics in the presence of catatonia and what factors to consider in a thorough risk-benefit analysis. The literature is especially limited in describing the risks and benefits of using long-acting injectable antipsychotics in the presence of catatonia. We describe four cases where patients with preexisting catatonia received long-acting injectable first generation antipsychotics and experienced severe adverse effects (three experienced worsening of catatonia and one experienced neuroleptic malignant syndrome). The evidence base for managing comorbid catatonia and psychosis remains underdeveloped and inconsistent, but there are numerous known risk factors for adverse antipsychotic reactions, which we describe in relation to these cases. Finally, we present best practices to consider when managing comorbid psychosis and catatonia, especially when considering the use of long-acting injectable antipsychotics.

Atypical Neuroleptic Malignant Syndrome With Type 2 Respiratory Failure Treated With Non-invasive Ventilation

Neuroleptic malignant syndrome (NMS) is characterized by hyperthermia, severe rigidity, and autonomic instability that is life-threatening if not treated promptly by intensive supportive care. However, there have been numerous reports of "atypical NMS" where the diagnostic criteria of NMS are only partially satisfied. We present a case of an elderly male who presented with atypical NMS secondary to antidopaminergic drug administration which precipitated acute respiratory failure. Our patient exhibited features of severe rigidity and autonomic instability, without hyperthermia. He developed tachypneic hypoventilation with type 2 hypercapneic respiratory failure which was treated with non-invasive ventilation (NIV). The patient recovered after three days with resolution of rigidity and was transferred to a normal medical ward on oxygen via a facemask, where he gradually improved. This study highlights that non-invasive ventilation may have a role in treating respiratory failure in mild to moderate cases of atypical NMS, avoiding the need for intubation.

Symptomatic, functional and quality of life measures of remission in 194 outpatients with schizophrenia followed naturalistically in a 6-month, non-interventional study of aripiprazole once-monthly

An important goal in the treatment of patients with schizophrenia is remission in various domains, i.e., of symptoms, psychosocial functioning and subjective well-being. We undertook a post hoc analysis of pre-stabilized outpatients with schizophrenia and complete outcome data who had been enrolled in a 6-month non-interventional study of aripiprazole once-monthly (AOM) at 75 German sites. Key outcomes were (i) symptomatic remission (cross-sectional Andreasen et al. criteria (≤mild positive and negative key symptoms on the Brief Psychiatric Rating Scale (BPRS))); (ii) functional remission (Global Assessment of Functioning (GAF) scale score >70), and (iii) subjective well-being remission (WHO-5 scale score ≥13) at week 24. Of 242 enrolled patients, 194 (80.2%) (age = 43.9 ± 15.3 years; 51.5% male, illness duration = 14.0 ± 12.0 years) with complete data were analyzed. While 61.3% of the patients achieved symptomatic remission and 76.8% achieved remission regarding subjective well-being, only 24.7% achieved psychosocial functioning remission at 6 months. Remission rates were similar for men and women and across strata of disease duration with, on average, less remission in patients with longer illness duration. Correlations of improvements on the BPRS and GAF were weak, with the weakest correlation between the BPRS depressive mood item and the GAF scale, but similarly high correlation between BPRS subscales or the BPRS depressive mood item and subjective well-being. These findings suggest that while treatment with AOM can lead to symptomatic remission and remission regarding subjective well-being, additional interventions such as psychosocial therapy or supported employment and education may be necessary to achieve functional remission.

Clozapine Optimization: A Delphi Consensus Guideline From the Treatment Response and Resistance in Psychosis Working Group

BACKGROUND AND HYPOTHESIS

There is limited evidence to guide the approaches to clozapine treatment. Accordingly, an international initiative was undertaken with the aim of developing consensus recommendations for the optimization of clozapine monotherapy.

STUDY DESIGN

We conducted an online Delphi survey among members of the Treatment Response and Resistance in Psychosis (TRRIP) working group comprising experts from twenty-nine countries. The threshold criterion for a consensus recommendation was ≥ 75% agreement ("agree" and "strongly agree" responses) on a question. Agreement of ≥ 50% but < 75% in a second or third Delphi round was deemed to provide guidance.

STUDY RESULTS

Forty-nine (first round), 32 (second round), and 48 (third round) of the 91 current TRRIP members participated. Expert recommendations at ≥ 75% comprised second-line treatment with clozapine in cases of persistent positive symptoms with co-occurring extrapyramidal symptoms, tardive dyskinesia, or suicidality/aggression. There was considerable disagreement on myocarditis screening parameters. The management of somatic and neuropsychiatric adverse drug reactions warrants further research for more evidence-based recommendations. Rechallenge with clozapine was recommended for eosinophilia, sinus tachycardia and fever and guidance (agreement ≥ 50%) was reached for pneumonia and thrombocytopenia.

CONCLUSIONS

Given the limited evidence available, this consensus-based series of recommendations and guidance statements supports clinical decision-making to optimize clozapine monotherapy and provides guidance for future research in treatment-resistant schizophrenia.

Delphi panel to obtain clinical consensus about using long-acting injectable antipsychotics to treat first-episode and early-phase schizophrenia: treatment goals and approaches to functional recovery

BACKGROUND

Schizophrenia is mostly a chronic disorder whose symptoms include psychosis, negative symptoms and cognitive dysfunction. Poor adherence is common and related relapse can impair outcomes. Long-acting injectable antipsychotics (LAIs) may promote treatment adherence and decrease the likelihood of relapse and rehospitalization. Using LAIs in first-episode psychosis (FEP) and early-phase (EP) schizophrenia patients could benefit them, yet LAIs have traditionally been reserved for chronic patients.

METHODS

A three-step modified Delphi panel process was used to obtain expert consensus on using LAIs with FEP and EP schizophrenia patients. A literature review and input from a steering committee of five experts in psychiatry were used to develop statements about patient population, adverse event management, and functional recovery. Recruited Delphi process psychiatrists rated the extent of their agreement with the statements over three rounds (Round 1: paper survey, 1:1 interview; Rounds 2-3: email survey). Analysis rules determined whether a statement progressed to the next round and the level of agreement deemed consensus. Measures of central tendency (mode, mean) and variability (interquartile range) were reported back to help panelists assess their previous responses in the context of those of the overall group.

RESULTS

The Delphi panelists were 17 psychiatrists experienced in treating schizophrenia with LAIs, practicing in seven countries (France, Italy, US, Germany, Spain, Denmark, UK). Panelists were presented with 73 statements spanning three categories: patient population; medication dosage, management, and adverse events; and functional recovery domains and assessment. Fifty-five statements achieved ≥ 80% agreement (considered consensus). Statements with low agreement (40-79%) or very low agreement (< 39%) concerned initiating dosage in FEP and EP patients, and managing loss of efficacy and breakthrough episodes, reflecting current evidence gaps. The panel emphasized benefits of LAIs in FEP and EP patients, with consensus that LAIs can decrease the risk of relapse, rehospitalization, and functional dysfunction. The panel supported links between these benefits and multidimensional longer-term functional recovery beyond symptomatic remission.

CONCLUSIONS

Findings from this Delphi panel support the use of LAIs in FEP and EP schizophrenia patients regardless of disease severity, number of relapses, or social support status. Gaps in clinician knowledge make generating evidence on using LAIs in FEP and EP patients critical.

Candidate biomarkers in psychiatric disorders: state of the field

The field of psychiatry is hampered by a lack of robust, reliable and valid biomarkers that can aid in objectively diagnosing patients and providing individualized treatment recommendations. Here we review and critically evaluate the evidence for the most promising biomarkers in the psychiatric neuroscience literature for autism spectrum disorder, schizophrenia, anxiety disorders and post-traumatic stress disorder, major depression and bipolar disorder, and substance use disorders. Candidate biomarkers reviewed include various neuroimaging, genetic, molecular and peripheral assays, for the purposes of determining susceptibility or presence of illness, and predicting treatment response or safety. This review highlights a critical gap in the biomarker validation process. An enormous societal investment over the past 50 years has identified numerous candidate biomarkers. However, to date, the overwhelming majority of these measures have not been proven sufficiently reliable, valid and useful to be adopted clinically. It is time to consider whether strategic investments might break this impasse, focusing on a limited number of promising candidates to advance through a process of definitive testing for a specific indication. Some promising candidates for definitive testing include the N170 signal, an event-related brain potential measured using electroencephalography, for subgroup identification within autism spectrum disorder; striatal resting-state functional magnetic resonance imaging (fMRI) measures, such as the striatal connectivity index (SCI) and the functional striatal abnormalities (FSA) index, for prediction of treatment response in schizophrenia; error-related negativity (ERN), an electrophysiological index, for prediction of first onset of generalized anxiety disorder, and resting-state and structural brain connectomic measures for prediction of treatment response in social anxiety disorder. Alternate forms of classification may be useful for conceptualizing and testing potential biomarkers. Collaborative efforts allowing the inclusion of biosystems beyond genetics and neuroimaging are needed, and online remote acquisition of selected measures in a naturalistic setting using mobile health tools may significantly advance the field. Setting specific benchmarks for well-defined target application, along with development of appropriate funding and partnership mechanisms, would also be crucial. Finally, it should never be forgotten that, for a biomarker to be actionable, it will need to be clinically predictive at the individual level and viable in clinical settings.

Long-acting antipsychotics in the treatment of schizophrenia: opportunities and challenges

INTRODUCTION

Maintenance antipsychotic treatment improves multiple outcomes in people with schizophrenia. These benefits are challenged by medication nonadherence, which is a common occurrence. Long-acting injectable antipsychotic (LAI) formulations were developed to reduce nonadherence and thereby improve outcomes. This narrative review is based on a PubMed search (January 2000 - August 2022) for studies on LAI antipsychotics.

AREAS COVERED

Opportunities and challenges associated with LAIs are reviewed. Advantages, compared to oral antipsychotics (OAs), include improved adherence, reduced relapse and hospitalization risk, delayed and lower relapse risk after stopping treatment, and the ability to differentiate true treatment resistance from 'pseudo'-resistance. Additionally, LAIs are associated with lower all-cause mortality than OAs. LAIs are under-used in many services, partly reflecting negative attitudes, misconceptions, and lack of knowledge among clinicians, patients, and carers. Practical barriers to LAI use include acquisition costs and inadequate service structures to administer/monitor LAI treatment.

EXPERT OPINION

The education and engagement of clinicians, patients and caregivers can assist more informed decision-making regarding LAIs. Future research regarding LAIs should encompass multiple complementary designs, focus on functionality and recovery outcomes, and include groups at high risk of relapse, including those with comorbid substance use disorders and early in the course of schizophrenia.

Tolerability profile of paliperidone palmitate formulations: A pharmacovigilance analysis of the EUDRAVigilance database

Introduction

Long-acting injectable antipsychotics (LAIs) have proven to be effective in the maintenance treatment of patients suffering from schizophrenia, and their safety and tolerability profiles represent a key factor in their long-term use and choice in clinical practice. Paliperidone palmitate (PP) is the only second-generation LAI (SGA-LAI), available in both one- (PP1M) and 3-month (PP3M) formulations. However, real-world prospective studies on PP1M and PP3M are still few and mostly conducted on small samples. In this context, we aimed to better define the safety and tolerability profile of PP using real world pharmacovigilance data.

Methods

We retrospectively analyzed the publicly available data regarding Individual Case Safety Reports (ICSRs), presenting PP1M and/or PP3M as suspected drugs, reported on EUDRAVigilance between 2011 and June 30th, 2022. ICSRs relative to at least one SGA-LAI other than PP, reported between 2003 and June 30th, 2022, were also examined as reference group. Data were evaluated with a descriptive analysis, and then, as disproportionality measures, crude reporting odds ratio (ROR) and 95% confidence interval (CI) were calculated.

Results

A total of 8,152 ICSRs met the inclusion criteria, of those 77.7% (n = 6,332) presented as suspected drug PP1M, 21.2% (n = 1,731) PP3M, while 89 cases indicated both PP1M and PP3M. Significantly higher probabilities of reporting in PP-related reports were observed for the primary Standardized MedDRA Queries "Sexual Dysfunctions" (ROR = 1.45; 95% CI 1.23-1.70), "Haemodynamic oedema, effusions and fluid overload" (ROR = 1.42; 1.18-1.70), as well as "Fertility disorders" (ROR = 2.69; 1.51-4.80).

Discussion

Our analysis indicates that the tolerability and safety profiles of PP are in line with what is known for the other SGA-LAIs. However, differences regarding endocrine system ADRs have been noticed. The results presented in this work do not discourage the prescription of SGA-LAI formulations but aim to enhance their safety.

Attitude and influencing factors of patients with schizophrenia toward long-acting injections: A community-based cross-sectional investigation in China

Background

Low prescription rates of antipsychotic long-acting injections (LAIs) may be a major challenge in the prevention and treatment of schizophrenia. However, there are few studies on the usage and attitude toward LAIs among community-based patients with schizophrenia.

Methods

A large community-based cross-sectional investigation was conducted among 6,336 patients with schizophrenia from Shanghai, China from March 1 to June 30, 2021. The structured Attitude and Status toward Treatment of Community Patients with Schizophrenia Questionnaire (AST-CSQ) was used to investigate the attitude and influencing factors of community-dwelling patients with schizophrenia toward LAIs.

Results

Among the 6,336 participants, the average age was 49.28 ± 11.23. The rate of agreement to LAI antipsychotics among participants was 3.16% (n = 200). The family financial resources, care ability, and disease course of the LAIs group were less than those of the non-LAIs group. However, the LAIs group had higher immediate family guardianship, social activity, previous hospitalization, number of hospitalization, outpatient adherence, previous antipsychotic use, antipsychotic adherence, and attitude toward oral antipsychotics than the non-LAIs group, with significant differences between the two groups (p < 0.05). Furthermore, age (β = -0.036, OR 0.964, 95% CI 0.947-0.982), marital status (β = 0.237, OR 1.267, 95% CI 1.002-1.602), care ability (β = 0.709, OR 2.032, 95% CI 1.437-2.875), outpatient adherence (β = -0.674, OR 0.510, 95% CI 0.358-0.725), antipsychotic adherence (β = 0.920, OR 2.509, 95% CI 1.092-5.764), and attitude toward oral antipsychotics (β = -1.357, OR 0.258, 95% CI 0.103-0.646) were significant predictors of attitude toward LAI antipsychotics (p < 0.05).

Conclusions

The community-dwelling patients with schizophrenia in China had a low willingness to use LAIs. Patients of a younger age, more hospitalizations, and a shorter course of disease were prone to be more willing to accept LAIs. The patients' age, marital status, care ability, outpatient adherence, antipsychotic adherence, and attitude toward oral antipsychotics were important predictor of patients' attitudes toward LAIs. Under the global deinstitutionalized management model of mental disorders, these results highlight an urgent problems for public mental health service providers and policy-makers and provide more solutions for them.

Clozapine Treatment Is Associated With Higher Prescription Rate of Antipsychotic Monotherapy and Lower Prescription Rate of Other Concomitant Psychotropics: A Real-World Nationwide Study

BACKGROUND

Although clozapine is effective for treatment-resistant schizophrenia (TRS), the rate of clozapine prescription is still low. Whereas antipsychotic monotherapy is recommended in clinical practice guidelines, the rate of antipsychotic polypharmacy is still high. There is little evidence on whether a clozapine prescription influences changes in the rate of monotherapy and polypharmacy, including antipsychotics and other psychotropics. We therefore hypothesized that the rate of antipsychotic monotherapy in patients with TRS who were prescribed clozapine would be higher than that in patients with schizophrenia who were not prescribed clozapine.

METHODS

We assessed 8306 patients with schizophrenia nationwide from 178 institutions in Japan from 2016 to 2019. We analyzed the psychotropic prescription data at discharge in patients diagnosed with TRS and with no description of TRS (ND-TRS) based on the diagnosis listed in the discharge summary.

RESULTS

The rate of antipsychotic monotherapy in the TRS with clozapine group (91.3%) was significantly higher than that in the TRS without clozapine group (45.9%; P &lt; 2.0 × 10-16) and the ND-TRS without clozapine group (54.7%; P &lt; 2.0 × 10-16). The rate of antipsychotic monotherapy without any other concomitant psychotropics in the TRS with clozapine group (26.5%) was significantly higher than that in the TRS without clozapine group (12.6%; P = 1.1 × 10-6) and the ND-TRS without clozapine group (17.0%; P = 5.9 × 10-6).

CONCLUSIONS

Clozapine prescription could be associated with a high rate of antipsychotic monotherapy. Patients will benefit from the correct diagnosis of TRS and thus from proper clozapine prescription.

The pharmacological treatment of schizophrenia: How far have we come?

Schizophrenia is a chronic and often severe mental disorder for which antipsychotic drugs are the cornerstone of treatment. Although the essential mechanism of action of these drugs has not changed much since they were first discovered in the 1950s, there have been numerous advances in the context in which these drugs are prescribed, as well as in the considerations for their optimal use. In this review, we summarize five selected issues in which the psychopharmacological treatment of schizophrenia has most evolved. Namely, these are the shift of outcomes of interest from symptoms to recovery, the development of stratified approaches to select the most appropriate treatment for each individual, the recognition of treatment nonadherence as a critical factor determining outcomes, the recommendations for maintenance treatment, and, finally, the promise of new antipsychotic compounds that innovate in their mechanisms of action, improving efficacy/safety profiles. Finally, we discuss how some of these advances have already delivered to improved outcomes in the real world, whereas others have demonstrated efficacy under optimal circumstances yet have not been translated into better outcomes in the community. Thus, the road ahead includes both identifying novel treatments that engage the psychopathology of the illness and improve the efficacy/tolerability profile of currently available agents, as well as developing interventions that mitigate the barriers for the use of novel interventions, some of them already existing, in the real world.

Diagnostic error regarding the cause of cytopenia when increasing psychotropic drugs: Two case reports

Several psychotropic drugs can cause cytopenia, especially after increasing dosages or initiating treatment. However, cytopenia in patients with psychiatric disorders can also be due to other conditions such as leukemia. In this report, we discuss two cases of cytopenia that occurred during the adjustment of psychotropic medications in patients with severe psychiatric illness. The initial diagnosis in each case was drug-induced cytopenia; however, later, the cause of cytopenia was found to be acute promyelocytic leukemia. When cytopenia is observed while increasing the dosage of psychotropic drugs, suspicious drugs should be discontinued, though the possibility that cytopenia could be due to other reasons should be considered. If there are no signs of recovering blood cells or if cytopenia is severe, psychiatrists should consult hematologists promptly.

Long-Acting Injectable Antipsychotic Treatment in Schizophrenia and Co-occurring Substance Use Disorders: A Systematic Review

Objectives: Co-occurring substance use disorders (SUDs) among individuals with schizophrenia are a prevalent and complex psychiatric comorbidity, which is associated with increased symptom severity, worsened illness trajectory and high rates of treatment non-adherence. Recent evidence suggests that the use of long-acting injectable (LAI) antipsychotics may provide an effective treatment option for individuals with this dual-diagnosis. Methods: A systematic review of the literature was conducted using the databases PubMed, PsychInfo and Google Scholar for English-language studies, investigating the use of LAIs in co-occurring schizophrenia and substance use disorders (SCZ-SUDs). Results: Eight reports [one case study (n = 1), one case series (n = 8), three open-label retrospective studies (n = 75), and three randomized controlled trials (n = 273)] investigated the use of LAI antipsychotics in 357 participants with SCZ-SUDs [alcohol use disorder: 5 studies, n = 282; cocaine use disorder: 5 studies, n = 85; amphetamine use disorder: 1 study, n = 1; cannabis use disorder: 3 studies, n = 160; opioid use disorder: 3 studies, n = 19; methylenedioxymethamphetamine (MDMA) use disorder: 2 studies, n = 9; ketamine use disorder: 1 study, n = 4] and were included in this systematic review. Findings indicate significant improvements in substance use related outcomes across 7 of 8 studies, while in 6 of 8 studies, significant improvements in psychopathology-related outcomes were reported. Conclusions: LAI antipsychotics may be an efficacious intervention option for the treatment of SCZ-SUDs. However, varying methodological rigor, generally small sample sizes and heterogeneity of samples, settings, substances of abuse, tested LAIs and comparators, as well as psychosocial cotreatments and level of reported detail across studies requires that these findings be considered preliminary and interpreted with caution. Further research is required to better understand the effects of LAIs among individuals with SCZ-SUDs.