Intranasal drug delivery in neuropsychiatry: focus on intranasal ketamine for refractory depression

Introduction

Medications used in neuropsychiatry are most commonly given orally or parenterally, but intranasal drug delivery (INDD) has been available for decades and is supported by a substantial animal literature and longstanding clinical use in other fields. INDD offers several theoretical and practical advantages for brain-targeted treatments, including rapid absorption from the intranasal vascular bed, avoidance of gastrointestinal degradation and first‑pass hepatic metabolism, and the potential to bypass the blood–brain barrier via olfactory pathways. Andrade sets out to review the applications and advantages of INDD in neuropsychiatry, and to focus in particular on the potential role of intranasal ketamine for acute management and maintenance therapy of refractory depression. The article synthesises examples of approved and experimental intranasal treatments and highlights gaps in evidence, especially regarding repeated‑dose and maintenance strategies for intranasal ketamine.