Fluphenazine decanoate injection—a long-acting, depot antipsychotic administered once every 2–4 weeks—is a critical maintenance therapy for schizophrenia and related chronic psychotic disorders, ensuring adherence where oral regimens fail. The global Fluphenazine Decanoate Injection market size surpassed USD 140 million in 2025 and is projected to expand at a 4.6% CAGR through 2033, underpinned by rising treatment-refractory schizophrenia prevalence, government-funded mental-health programs, and cost-effective generic availability. Scope includes 2.5 mL and 5 mL ampoules/vials (25 mg/mL) sold via hospital, retail, and e-commerce channels; synonyms covered are fluphenazine depot, Modecate®, Prolixin Decanoate, and long-acting injectable (LAI) first-generation antipsychotic (FGA).