Abstract
Background/Objectives: Bipolar disorder (BD) and obsessive-compulsive disorder (OCD) often coexist, presenting significant challenges in treatment. OCD comorbidity in BD is associated with severe clinical features such as increased suicidality and impaired functioning. While selective serotonin reuptake inhibitors (SSRIs) are effective for OCD, they may increase manic shifts in BD patients. The use of long-acting injectable (LAI) antipsychotics such as monthly aripiprazole (ARI-LAI) and monthly paliperidone (PP-LAI) has been proposed as a promising alternative for BD treatment, while their efficacy and safety in BD-OCD remain understudied. This study investigated the effectiveness and tolerability of ARI-LAI and PP-LAI as adjunctive therapies in this population. Methods: 27 BD-OCD patients were treated with ARI-LAI or PP-LAI, alongside mood stabilizers (MS) (lithium or sodium valproate), over a 24 week period. Clinical and psychopathological assessments were performed at baseline and regular intervals using the Yale-Brown Obsessive Compulsive Scale and the Hamilton Depression Rating Scale. Safety and tolerability were evaluated using the UKU Side Effect Rating Scale. Results: Both treatments led to significant reductions in obsessive-compulsive symptoms and mood stabilization without manic episodes. ARI-LAI showed superior tolerability in terms of body weight gain compared to PP-LAI, with no significant differences in overall efficacy between the groups. Conclusions: This study is the first that investigated the efficacy and safety of adjunctive PP-LAI and ARI-LAI in this population highlighting their potential as effective and well-tolerated options for managing BD-OCD. Further studies are needed to confirm these results and refine treatment strategies for this complex population.