Third-Generation Antipsychotics as Augmentation in Treatment-Resistant Obsessive–Compulsive Disorder: A Narrative Review of Efficacy and Tolerability

<b>Background/Objectives</b>: Obsessive-compulsive disorder (OCD) is a chronic psychiatric illness with intrusive obsessions and compulsive behaviors severely impacting daily functioning and quality of life. The purpose of this narrative review is to present an updated summary of available evidence on third-generation antipsychotics (TGAs) as augmentation strategies for SRI-refractory OCD. <b>Methods</b>: The literature was reviewed using the PubMed database to recognize studies on the use of TGAs in treatment-resistant OCD. Only articles in the English language and on human participants were included. <b>Results</b>: We included nine reports in our review. More numerous (five reports) and higher evidence-level reports were retrieved for aripiprazole, which consistently shows high response rates compared to placebo and other antipsychotics. Two cohort studies were included on brexpiprazole, with no active or placebo comparator. These showed varying but high response rates. One cohort study reported a response rate of 61.5% to cariprazine. Only one paper reported on the efficacy of lumateperone in OCD. This was a single-case report on an adolescent patient with refractory OCD responding to lumateperone monotherapy. <b>Conclusions</b>: The current state of evidence supports the clinical utility of TGAs, particularly aripiprazole, in augmenting SRI treatment in patients with refractory OCD. Evidence regarding cariprazine and lumateperone is scarce, but still contributes to the discussion on the use of TGAs in OCD.