Once-Monthly Olanzapine for Schizophrenia, With Christoph Correll, MD

The US Food and Drug Administration (FDA) approval of olanzapine extended-release injectable suspension (Weltruza) gives clinicians a once-monthly olanzapine option for adults with schizophrenia without the post-injection observation period required by the earlier long-acting formulation, according to Christoph Correll, MD. Correll, a clinical professor of psychiatry at the Zucker School of Medicine at Hofstra/Northwell, discussed the approval and the case for continuous antipsychotic coverage with HCPLive.¹

Correll served as principal investigator of the SOLARIS program supporting the approval and noted he presents on the agent on behalf of Teva Pharmaceuticals.

Why did a practical long-acting olanzapine take so long?

Olanzapine has long been a cornerstone of schizophrenia treatment, Correll explained, and long-acting injectables (LAIs) are central to care given how often patients relapse. He cited reduced hospitalization, better functional outcomes, and even longer survival among patients maintained on LAIs.

The previously available monthly olanzapine LAI, given by deep intramuscular injection, required a 3-hour observation period after each dose, along with emergency resources on hand. Correll said patient reluctance and limited hospital resources made this requirement a major obstacle to use.

Weltruza is instead administered subcutaneously, which Correll suggested could also reduce the stigma associated with LAIs. He described the formulation as removing the injection barrier and making long-acting olanzapine broadly accessible.

What did the SOLARIS trial show?

The phase 3 SOLARIS trial (NCT05693935) randomized 675 adults with an acute exacerbation of schizophrenia to 1 of 3 subcutaneous olanzapine doses or placebo for 8 weeks. All 3 doses reduced Positive and Negative Syndrome Scale total scores more than placebo at week 8, with differences ranging from 9.75 to 11.27 points.¹˒²

No suspected or confirmed cases of post-injection delirium/sedation syndrome were reported across approximately 3487 injections in the program as of March 2025. Approved doses of 318 mg, 425 mg, and 531 mg correspond to oral olanzapine doses of 10 mg, 15 mg, and 20 mg daily, and no loading dose or oral supplementation is required.¹

Why does continuous antipsychotic coverage matter?

Patients often respond well early in treatment, Correll noted, but relapse risk climbs sharply once they stop medication because of improvement or side effects. Each relapse carries biological, psychological, and social costs, including gray matter loss, self-stigma, and greater emergency and hospital use.

Correll pointed to secondary treatment resistance as a particular concern. Roughly 20% of patients respond poorly from the outset, he said, but the proportion doubles to about 40% when relapses are allowed to occur, through mechanisms not yet fully understood.

Drawing comparisons to multiple sclerosis and cancer, where the first remission is typically the strongest, Correll framed acute response as the start of a longer path. Maintaining stability allows patients to engage in rehabilitation and work toward recovery.

He identified nonadherence as the main driver of relapse and noted it often goes undetected. LAIs make adherence visible, he explained, because clinicians know whether a patient has returned for each injection.

Editor’s note: This summary was edited for the purposes of clarity using AI tools. Correll has disclosed serving as a consultant or advisor to, or receiving honoraria or research support from, AbbVie/Allergan, Alkermes, Bristol Myers Squibb/Karuna Therapeutics, Eli Lilly, Intra-Cellular Therapies, Janssen/Johnson & Johnson, Lundbeck, Otsuka, Sunovion, and Teva Pharmaceuticals.

References

1. Klein HE. FDA approves once-monthly subcutaneous olanzapine for schizophrenia. AJMC. October 9, 2026. Accessed October 22, 2026. https://www.ajmc.com/view/fda-approves-once-monthly-subcutaneous-olanzapine-for-schizophrenia.

2. Olanzapine LAI (TEV-‘749) in adults with schizophrenia (SOLARIS). ClinicalTrials.gov identifier: NCT05693935. Accessed October 22, 2026. https://clinicaltrials.gov/study/NCT05693935.