A 36-year-old male with treatment-resistant schizophrenia has been stable on clozapine 450 mg daily (serum level 420 ng/mL) for 2 years. He now presents with new-onset obsessive-compulsive symptoms, intrusive contamination fears and ritualized handwashing consuming 3 hours daily, significantly impairing his functioning. OCD comorbidity with clozapine use is well-documented. The PMHNP determines an SSRI is indicated. Fluvoxamine has the strongest evidence base for OCD, but the PMHNP must consider the CYP1A2 interaction. Which of the following is the most appropriate pharmacologic approach?