Unmet Needs and Mechanisms: Understanding Adjunctive Antipsychotics in MDD

In "Unmet Needs and Mechanisms: Understanding Adjunctive Antipsychotics in MDD," the mental health experts examined the following critical questions:

What are the most important unmet needs in the current antidepressant treatment landscape, in terms of efficacy, tolerability, and adherence, that adjunctive therapies are trying to address?a. How do metabolic side effects, weight gain, akathisia, and sedation affect treatment persistence and, downstream, total cost of care for payers?

There are currently five FDA-approved atypical antipsychotics for adjunctive treatment in major depressive disorder (MDD): aripiprazole, quetiapine XR, brexpiprazole, cariprazine, and lumateperone. Can you briefly orient the panel to the class, shared mechanism, shared indication, and the key pharmacologic differences that distinguish them?

How do differences in receptor binding profiles — SERT/D1 receptor activity, D2/D3 partial agonism versus antagonism, 5-HT1A activity, and 5-HT2A antagonism — translate into clinical differences in efficacy and tolerability?

Led by the moderator, the panelists discussed persistent efficacy, tolerability, and adherence gaps in antidepressant treatment, noting that only about 60% of patients with MDD receive treatment and roughly 30% develop treatment resistance, with early adverse effects often undermining adherence before benefits take hold. Thase then oriented the panel to the five FDA-approved adjunctive atypical antipsychotics, explaining their shared serotonin-dopamine antagonism mechanism and lower risk of Parkinsonian side effects relative to first-generation antipsychotics, while highlighting how differences in receptor binding and partial agonism drive meaningful variation in efficacy and tolerability across agents.

Throughout the conversation, the experts provided a comprehensive reflection on the field and the factors that may shape how clinicians approach care moving forward.

Our next episode, "From the Exam Room to the Formulary: Access Challenges in Adjunctive MDD Therapy," further explores major depressive disorder, highlighting tolerability counseling and anticipatory guidance in clinical practice, alongside the structural payer barriers — prior authorization, step therapy, and formulary tier placement — that affect timely access to adjunctive antipsychotic therapy.