Pharmacological augmentation in treatment-resistant depression: a neurobiologically informed, practical decision guide for treatment choice with lithium, quetiapine, or esketamine.
David Eckert, Siegfried Kasper
International journal of psychiatry in clinical practice April 29, 2026 Peer reviewed DOI: 10.1080/13651501.2026.2663307 via PubMed
Summary
Lithium, quetiapine, and esketamine are augmentation strategies for treatment-resistant depression (TRD) that differ in their pharmacological profiles and clinical applications. They converge on neuroplasticity pathways but lack validated predictive markers for individual response. A decision-making framework based on clinical, somatic, and practical factors can aid in selecting the most appropriate treatment, tailored to the patient's specific psychiatric presentation and comorbidities.
Study at a glance
| Design | narrative review |
|---|---|
| Key finding | Lithium, quetiapine, and esketamine serve as augmentation strategies in TRD, each with distinct clinical characteristics that inform treatment selection. |
Abstract
The treatment of treatment-resistant depression (TRD) remains a clinical challenge. Pharmacologically, several augmentation options exist. The aim of this study was to present a mechanistically informed and clinically oriented decision-making framework for the established strategies of lithium, quetiapine, and esketamine. We conducted a narrative, non-systematic review, performing a targeted literature search on neurobiological mechanisms of action, clinical effects, and psychiatric, somatic, and practical decision-making factors. We considered international guidelines and supplemented them with clinical experience. Lithium, quetiapine, and esketamine differ substantially in pharmacological profile, monitoring requirements, and clinical application. Although their mechanisms of action vary, they appear to converge on pathways related to neuroplasticity. Their distinct clinical characteristics may guide treatment selection depending on psychiatric presentation, somatic comorbidity, and practical feasibility. All three agents represent augmentation strategies in TRD. A structured evaluation of clinical, somatic, and practical factors may support individualised treatment selection. However, validated predictive markers for differential response are currently lacking.