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Novel Schizophrenia Treatments

CE / CME

Strategic Steps in Schizophrenia: Mastering Modern Muscarinic Management

Psychologists: 0.50 APA CE Credit

Social Workers: 0.50 ASWB ACE CE Credit

Physician Assistants/Physician Associates: 0.50 AAPA Category 1 CME credit

Nurse Practitioners/Nurses: 0.50 Nursing contact hour

Pharmacists: 0.50 contact hour (0.05 CEUs)

Physicians: maximum of 0.50 AMA PRA Category 1 Credit™

Released: July 24, 2025

Expiration: July 23, 2026

Joseph P. McEvoy
Joseph P. McEvoy, MD
CME/CE Information

Activity

Progress
1 2
Course Completed

Case Conclusion
After the transition to xanomeline/trospium, the identification of the optimal dose for Andrew (the standard maintenance dose), and the addition of ondansetron 4 mg by mouth twice daily to manage nausea and occasional vomiting, Andrew and his parents were very satisfied with the outcome. He had sustained remission from psychosis and was free of restlessness. His bowels move regularly and his weight, glycated hemoglobin, and lipid panel are all in the normal range. He reported, and his parents and colleagues at work confirmed, improved clarity of thinking and new memory acquisition. He continues to live with his parents and works full-time at the grocery store.

Andrew’s aunt spoke with her psychiatrist and has also switched treatment to xanomeline/trospium. She has obtained a pedometer and strives to get several thousand steps each day. Her weight is gradually decreasing, and her glycated hemoglobin and lipid levels are returning to the normal range.

Discussion
Schizophrenia is a chronic, severe psychiatric illness affecting about 1% of the world population.28 It is a serious cause of disability, often striking in late adolescence or early adulthood. The traditional dopamine hypothesis of schizophrenia suggested that excess dopamine transmission, particularly through D2 receptors, underlies positive psychophathology.29 This model has evolved substantially. Current understanding recognizes that schizophrenia involves interactions between the dopaminergic, glutamatergic, GABAergic, serotonergic, and cholinergic systems.30

Schizophrenia treatment has evolved significantly over the past century. Most treatments have largely targeted dopamine receptors with antagonists or partial agonists, which effectively mitigate positive symptoms but offer only modest benefits for the cognitive and/or negative psychopathology domains. This gap in treating all facets of schizophrenia represents a major unmet need in care. Patients often suffer persistent negative symptoms (~40%) or cognitive impairment (80%), despite antipsychotic therapy.31

First-generation antipsychotics (FGAs) were developed to act primarily through dopamine D2 receptor blockade. These medications are highly effective for positive symptoms, with many patients experiencing significant improvement. However, strong D2 antagonism in the nigrostriatal pathway leads to substantial EPS, including acute dystonia, akathisia, drug-induced parkinsonism, and tardive dyskinesia. EPS from patients taking FGAs represent a major cause of treatment discontinuation. These symptoms result from dopamine blockade in the basal ganglia, disrupting the balance between dopaminergic and cholinergic systems. Tardive dyskinesia, characterized by involuntary facial and limb movements, occurs in patients on long-term FGA therapy and may be irreversible.

SGAs were designed to provide antipsychotic efficacy while minimizing EPS. Although SGAs generally cause fewer movement disorders, they can introduce significant metabolic complications. Metabolic syndrome affects a substantial proportion of patients, with SGAs causing a three-fold increased risk of severe weight gain, T2D, and cardiovascular disease.32 These metabolic effects result from complex interactions with hypothalamic centers via dopamine, serotonin, acetylcholine, and histamine receptors, affecting appetite regulation, insulin sensitivity, and lipid metabolism.

Recent developments in schizophrenia treatment have focused on novel mechanisms beyond direct dopamine blockade. Muscarinic acetylcholine receptors have emerged as particularly promising targets, with considerable evidence supporting their role in the pathophysiology of schizophrenia.33 Unlike traditional antipsychotics that primarily address positive symptoms, muscarinic receptor modulation shows potential for treating positive, negative, and cognitive symptoms collectively. Xanomeline/trospium represents a breakthrough in this area, recently approved as an innovative treatment for schizophrenia with a new mechanism of action not involving direct dopamine receptor blockade. This combination pairs xanomeline, a muscarinic M1 and M4 receptor agonist, with trospium, a peripherally acting muscarinic antagonist that does not cross the blood-brain barrier. This design allows central therapeutic effects while minimizing peripheral cholinergic side effects. Clinical trials have demonstrated that xanomeline/trospium significantly reduces positive symptoms with improvements observed as early as 5 weeks, and early evidence suggests that it may also have benefit in negative and cognitive domains.19,34

Modern schizophrenia treatment represents a complex integration of pharmacologic and psychosocial interventions that must address the multifaceted nature of this disorder. Although traditional direct dopamine-blocking antipsychotics remain essential for managing positive symptoms, the field has expanded to recognize the importance of cognitive enhancement, negative symptom treatment, and early intervention approaches. The approval of xanomeline/trospium marks a significant milestone, representing the first truly novel mechanism of action in schizophrenia treatment in decades, with much lower risk for EPS and metabolic effects such as weight gain, dyslipidemia, and insulin resistance. However, challenges remain in optimizing treatment selection, minimizing side effects, and addressing the substantial proportion of patients who do not achieve full recovery. Early intervention services demonstrate clear benefits during treatment periods, though maintaining long-term improvements requires continued study.35