Atypical Antipsychotic Drugs in Dual Disorders: Current Evidence for Clinical Practice

Background: Concurrent disorder or dual diagnosis refers to a combination of substance use disorders and mental disorders that occur in the same patient simultaneously. These conditions pose significant clinical and healthcare impacts and are often underdiagnosed, undertreated, and complex to manage. Objective: We assessed the quality of current pharmacological recommendations for the management of dual diagnosis, particularly by evaluating the use of second-generation antipsychotics (SGA). Methods: A literature search was performed using the PubMed and Scopus databases for publications up to September 21, 2021, without any time restrictions. The following search strings were used: (aripiprazole OR brexpiprazole OR cariprazine OR paliperidone OR risperidone OR quetiapine OR clozapine OR olanzapine) AND (psychosis OR schizophrenia OR schizoaffective) AND ("substance use disorder" OR cocaine OR alcohol OR cannabis OR heroin OR "double diagnosis" OR "dual diagnosis")) NOT (animal OR rat OR mouse) NOT (review or meta-analysis). Results: The search produced a final set of 41 articles. Most patients were males and were affected by schizophrenia, with cannabis the most abused substance, followed by alcohol. Aripiprazole was the most used drug, either orally or by long-acting formulations, followed by risperidone with oral and long-acting formulations, clozapine, olanzapine, and quetiapine. Conclusion: The findings highlight the use of SGA for the treatment of psychotic symptoms in comorbidity with substance use. Future studies on people with dual diagnosis and focused on long-term evaluations are warranted and need to investigate the efficacy of newly introduced molecules, such as partial D2 agonists and long-acting injectable antipsychotics.