Xanomeline with trospium in schizophrenia: dose and effects

A 27-year-old man has had schizophrenia for six years. On olanzapine, his symptoms improved, but he gained 14 kg in a year and his fasting glucose rose. He switched to aripiprazole and began to feel a restlessness that would not let him sit still, and he ended up stopping the medication on his own. Three weeks ago he started hearing voices again and becoming suspicious of his neighbors. He has no other known illnesses, takes no other medications and smokes ten cigarettes a day. His family asks whether there is a different medication that does not cause weight gain and does not cause this restlessness. The scene is fictional and was written for teaching.

This text uses the case as a clinical reasoning scenario for students and health professionals. It covers the combination of xanomeline with trospium chloride, the first antipsychotic approved in the United States that does not act by directly blocking the dopamine D2 receptor. The text explains the indication, the dose, the contraindications, the adverse effects, what the studies showed and where the limits of the evidence lie. It does not replace your institution's protocol or the local package insert. If you play the case of the day on NEXO, you will recognize the challenge: deciding with clues that arrive in sequence.

Key points

• Xanomeline with trospium (brand name Cobenfy) is indicated in the United States for schizophrenia in adults.
• Xanomeline is an agonist of muscarinic M1 and M4 receptors; trospium blocks these receptors outside the brain and reduces peripheral cholinergic effects.
• The dose starts at 50 mg with 20 mg twice a day, rises to 100 mg with 20 mg and can reach 125 mg with 30 mg twice a day, always away from meals.
• It is contraindicated in urinary retention, gastric retention, untreated narrow-angle glaucoma and moderate or severe hepatic impairment.
• In the 5-week studies, it improved symptoms more than placebo, without weight gain or relevant extrapyramidal symptoms; the most common effects were gastrointestinal.
• The regulatory dates in this text were checked with the FDA and the EMA on October 24, 2026.

Why this is a reasoning scenario

Antipsychotics used for decades act mainly by blocking the dopamine D2 receptor. A review recalls that they treat mainly the positive symptoms and leave many patients with negative symptoms and cognitive deficits (Żełabowski et al., 2026). They work, but many patients stop treatment because of adverse effects. A phase 3 study recalls that motor symptoms, risk of tardive dyskinesia, weight gain and drowsiness impair tolerability and adherence (Kaul et al., 2024). The relapse of the patient in the scene began exactly like this.

The scenario is good for training because it forces you to weigh efficacy, adverse effects and preferences. You need to understand the history of each medication, the reasons for stopping, physical health, the risk of relapse and what the patient and family expect. The post on signs, symptoms and history helps organize this collection, and the post on clinical decision-making recalls that switching antipsychotics is a decision that trades one set of risks for another.

What the scene teaches

The scene trains six habits. The first is recognizing akathisia and weight gain as causes of abandonment. The second is investigating other causes of worsening, such as substance use. The third is knowing the contraindications of the new combination. The fourth is explaining the dose on an empty stomach and the titration. The fifth is warning about nausea, constipation and urinary retention. The sixth is agreeing on when and how to reassess.

What is not at stake

The text does not discuss treatment-resistant schizophrenia, clozapine, long-acting injectables, children or psychosis associated with dementia. It also does not compare prices. The post on diagnostic uncertainty helps explain to the patient what is not yet known about a medication with little long-term experience.

The effects that drive the patient away from treatment

Weight gain and metabolism

A network meta-analysis compared 18 antipsychotics for their effect on weight, glucose and lipids (Pillinger and colleagues, 2020). It found weight gain with several of them, including olanzapine, clozapine, quetiapine, risperidone and paliperidone (Pillinger and colleagues, 2020). In the ranking by weight gain, haloperidol came out best and clozapine worst (Pillinger and colleagues, 2020). The authors estimate that about 6 weeks of olanzapine or clozapine raise weight by about 3 kg and triglycerides by about 1 mmol/L, which can increase cardiovascular risk (Pillinger and colleagues, 2020).

Akathisia

A network meta-analysis on antipsychotic-induced akathisia describes the condition as subjective restlessness, often with excessive movements, such as swinging the legs or being unable to stay seated (Gerolymos and colleagues, 2024). The main clinical recommendations are to keep a single antipsychotic, reduce the dose or switch to a drug with lower risk of akathisia (Gerolymos and colleagues, 2024). In this analysis, mirtazapine, biperiden and vitamin B6 were the most effective treatments (Gerolymos and colleagues, 2024).

The effects weigh on the choice

A systematic review on adverse effects of antidepressants and antipsychotics estimates that about 75 percent of patients have some adverse effect (Pillinger and colleagues, 2023). The authors note that these effects harm quality of life, cause stigma and reduce adherence, increasing the risk of relapse (Pillinger and colleagues, 2023). They also note that adverse effects are among the factors that weigh most for people with schizophrenia when deciding on treatment (Pillinger and colleagues, 2023). For the patient in the scene, this is the heart of the conversation.

How xanomeline with trospium works

The US label describes xanomeline as a muscarinic receptor agonist, with an effect on M1 and M4 in the central nervous system (US label of Cobenfy, 9/2024). The exact mechanism in the treatment of schizophrenia is not known (US label of Cobenfy, 9/2024). Trospium is a muscarinic antagonist that acts outside the brain (US label of Cobenfy, 9/2024).

The history of xanomeline

A 2026 review recounts that xanomeline was developed in the 1990s as a possible treatment for Alzheimer's disease (Żełabowski and colleagues, 2026). Peripheral cholinergic effects, such as nausea, vomiting and sweating, limited that development. The idea of the combination was to add a blocker that does not reach the brain.

The role of trospium

A pharmacology review describes trospium as a peripheral cholinergic antagonist with no ability to cross the blood-brain barrier (Żełabowski and colleagues, 2026). Through the blockade outside the brain, it reduces the peripheral cholinergic effects caused by xanomeline (Żełabowski and colleagues, 2026). Even so, gastrointestinal effects remain common, and the anticholinergic effects of trospium, such as constipation, dry mouth and urinary retention, appear in the studies (Ramey and Silva Almodóvar, 2025) (US label of Cobenfy, 9/2024).

Why this changes the profile

Because it does not interfere directly with dopamine pathways, the combination seeks antipsychotic efficacy while limiting the typical effects of D2 blockade (Żełabowski and colleagues, 2026). A literature review notes that it has no boxed warning about psychosis associated with dementia and does not require a risk mitigation program (Smith and colleagues, 2025). This does not mean an absence of risk: the label lists its own contraindications and warnings, linked to muscarinic action (US label of Cobenfy, 9/2024).

Regulatory status: FDA and EMA

United States. The FDA approved Cobenfy on September 26, 2024, under NDA 216158, as a new molecular entity, with standard review (Drugs@FDA, NDA 216158). On October 24, 2026, Drugs@FDA did not list later supplements (Drugs@FDA, NDA 216158). The label consulted was revised in September 2024 (US Cobenfy label, 9/2024). The indication is the treatment of schizophrenia in adults (US Cobenfy label, 9/2024). A review published shortly after approval describes the drug as a new approach in the treatment of schizophrenia (Hasan and Abid, 2024).

European Union. On October 24, 2026, we did not find a page for an authorized medicine for xanomeline with trospium on the EMA website. Therefore, this text does not describe the European regulatory situation.

Other countries. This text does not describe registration in other countries. Availability depends on the local agency.

What the studies showed

The first study

In the phase 2 EMERGENT-1 study, 182 inpatients with acute worsening of schizophrenia were randomized to xanomeline with trospium or placebo (Brannan et al., 2021). The primary outcome was the change on the PANSS scale, which ranges from 30 to 210 points, from baseline to week 5 (Brannan et al., 2021). The score fell 17.4 points with the drug and 5.9 points with placebo, a difference of 11.6 points (Brannan et al., 2021).

The phase 3 studies

In EMERGENT-3, 256 participants were randomized, 125 to xanomeline with trospium and 131 to placebo (Kaul et al., 2024). PANSS fell 20.6 points with the drug, and the difference from placebo was 8.4 points at week 5 (Kaul et al., 2024). The US label summarizes the two phase 3 studies: in the first, the drop was 21.2 versus 11.6 points, a difference of 9.6; in the second, 20.6 versus 12.2 points, a difference of 8.4 (US Cobenfy label, 9/2024). The median age was 46 years, and no participant was older than 65 (US Cobenfy label, 9/2024).

The pooled analysis

The pooled analysis of the three EMERGENT studies included 640 participants, 314 with the drug and 326 with placebo (Kaul et al., pooled analysis, 2024). PANSS fell 19.4 points with the drug and 9.6 with placebo, a difference of 9.9 points, with a Cohen effect size of 0.65 (Kaul et al., pooled analysis, 2024). The effect size was 0.81 in EMERGENT-1, 0.61 in EMERGENT-2 and 0.60 in EMERGENT-3 (Kaul et al., pooled analysis, 2024). The studies included people hospitalized for acute worsening, without oral antipsychotic for at least five half-lives or one week (Kaul et al., pooled analysis, 2024).

The table summarizes the three 5-week studies.

Study	Randomized participants	PANSS drop with the drug	PANSS drop with placebo	Difference	Source
EMERGENT-1, phase 2	182	17.4	5.9	11.6	(Brannan et al., 2021)
EMERGENT-3, phase 3	256	20.6	12.2	8.4	(Kaul et al., 2024) (US Cobenfy label, 9/2024)
Pooled analysis of the three studies	640 in the analysis	19.4	9.6	9.9	(Kaul et al., pooled analysis, 2024)

Adverse effects

In EMERGENT-3, the drug was not associated with weight gain or drowsiness compared with placebo (Kaul et al., 2024). There was no clinically relevant change on the extrapyramidal symptom scales, including the akathisia scale (Kaul et al., 2024). A review summarizes that, in this study, nausea occurred in 16.9 percent and vomiting in 9.0 percent with the drug, versus 4.4 percent each with placebo (Ramey and Silva Almodóvar, 2025). Constipation occurred in 16.9 percent and dry mouth in 9.0 percent, versus 3.3 and 1.1 percent with placebo (Ramey and Silva Almodóvar, 2025). Nausea lasted a median of 9 days, and vomiting, 1 day (Ramey and Silva Almodóvar, 2025).

The label lists as the most common adverse reactions nausea, dyspepsia, constipation, vomiting, hypertension, abdominal pain, diarrhea, tachycardia, dizziness and gastroesophageal reflux (US Cobenfy label, 9/2024). Total exposure in the studies was 1135 patients, 347 for at least 6 months and 150 for at least one year (US Cobenfy label, 9/2024).

How to read these numbers

The studies compared the drug with placebo, not with another antipsychotic, so they do not say whether it is more or less effective than olanzapine or aripiprazole. They were also conducted in hospitalized adults with acute worsening, with little data in older adults (US label for Cobenfy, 9/2024). The open-label extension studies EMERGENT-4 and EMERGENT-5 assess long-term use (Ramey and Silva Almodóvar, 2025). For the patient in the scene, the honest promise is a different side effect profile, not a drug without side effects. The post about diagnostic pause reminds us to stop before attributing all worsening to a lack of medication.

From switching medication to follow-up

Before prescribing, four questions change the approach: is there difficulty urinating, how are the liver and kidneys, is there glaucoma or a problem with stomach emptying, and which medications is the patient taking.

The dose

The US label calls for starting with 50 mg of xanomeline and 20 mg of trospium twice a day for at least 2 days (US label for Cobenfy, 9/2024). Then the dose goes up to 100 mg with 20 mg twice a day for at least 5 days (US label for Cobenfy, 9/2024). If tolerated and needed, it can go up to 125 mg with 30 mg twice a day, which is the maximum dose (US label for Cobenfy, 9/2024). The capsules should be taken at least 1 hour before or 2 hours after a meal, and should not be opened (US label for Cobenfy, 9/2024). In older adults, the label calls for starting with 50 mg with 20 mg, a slower titration and a maximum dose of 100 mg with 20 mg (US label for Cobenfy, 9/2024).

Contraindications

The combination is contraindicated in urinary retention, moderate or severe hepatic impairment, gastric retention, hypersensitivity to trospium and untreated narrow-angle glaucoma (US label for Cobenfy, 9/2024).

Warnings

The label calls for attention to urinary retention, especially in older adults and in people with prostatic hyperplasia (US label for Cobenfy, 9/2024). Use is not recommended in mild hepatic impairment or in moderate or severe renal impairment (US label for Cobenfy, 9/2024). There are warnings for biliary tract disease, reduced gastrointestinal motility, angioedema, increased heart rate and effects on the central nervous system, with caution when driving (US label for Cobenfy, 9/2024). Before starting and during treatment, as indicated, the label calls for measuring liver enzymes and bilirubin and measuring heart rate (US label for Cobenfy, 9/2024).

Interactions

The label calls for attention to drugs eliminated by active tubular secretion, to strong CYP2D6 inhibitors, to sensitive CYP3A4 and P-glycoprotein substrates and to other antimuscarinics, which may add to the effects (US label for Cobenfy, 9/2024).

• Start with 50 mg with 20 mg twice a day for at least 2 days.
• Go up to 100 mg with 20 mg twice a day for at least 5 days; maximum of 125 mg with 30 mg.
• Take at least 1 hour before or 2 hours after meals, without opening the capsule.
• Measure liver enzymes and bilirubin and measure heart rate before and during treatment.
• Do not use in urinary retention, gastric retention, untreated narrow-angle glaucoma or moderate or severe hepatic impairment.
• Review CYP2D6 inhibitors and other antimuscarinics.

Source of the list: (US label for Cobenfy, 9/2024).

Applying it to the patient

The patient is young, has no known disease of the liver, kidneys, prostate or eyes and does not use other medicines. The team confirms that he has no difficulty urinating, asks about symptoms of reflux and constipation, measures liver enzymes and bilirubin and measures heart rate (US prescribing information for Cobenfy, 9/2024). It also investigates substance use and other causes of worsening; the post on differential diagnosis helps to remember clinical causes of psychosis, such as medicines, thyroid diseases and infections. If the choice is xanomeline with trospium, he needs to understand the fasting schedule, the titration and the chance of nausea in the first weeks (US prescribing information for Cobenfy, 9/2024) (Ramey and Silva Almodóvar, 2025). The post on interprofessional clinical reasoning shows how psychiatry, nursing, pharmacy and family build this plan together.

Follow-up

The plan includes close appointments in the first weeks, monitoring of weight, blood glucose and lipids, attention to heart rate and blood pressure, questions about urine, bowels and gallbladder, and review of each new medicine (US prescribing information for Cobenfy, 9/2024) (Pillinger and colleagues, 2020). If there is akathisia or other motor effects, they should be recorded with the same attention given to improvement of symptoms (Gerolymos and colleagues, 2024).

How NEXO helps train this reasoning

In NEXO, the case of the day is fictional, with a real clinical presentation and up to six progressive clues, and you propose the diagnosis by searching for the ICD-10 code. Switching antipsychotics is a good exercise because a urinary symptom, an eye drop or a mealtime changes the approach. The post on case-based learning explains why this format fixes knowledge.

Three exercises with cases

Change the age. Say how to adjust the start and the maximum dose if the patient were 70 years old and had prostatic hyperplasia.

Change the liver. Say what to do if the initial dosage showed moderate hepatic impairment.

Change the course. Say what to investigate if he had pain in the right side of the abdomen and jaundice in the third week.

The post on simulation of consultations helps train the conversation with the patient and the family about adverse effects.

The limits of use of the game are described on the NEXO economy page. If you research teaching of clinical reasoning, the page for researchers explains how to get in touch. Professionals who write or review cases find information on curation and on creators, and institutions can learn about the proposal on the partnerships page.

Frequently asked questions

Does xanomeline with trospium block dopamine?

Not directly. Xanomeline is an agonist of muscarinic receptors M1 and M4 (US prescribing information for Cobenfy, 9/2024).

Does it cause weight gain?

In EMERGENT-3, it was not associated with weight gain compared with placebo over 5 weeks (Kaul and colleagues, 2024).

What is the dose?

It starts at 50 mg with 20 mg twice a day and can reach 125 mg with 30 mg twice a day, away from meals (US prescribing information for Cobenfy, 9/2024).

What are the most common effects?

Nausea, dyspepsia, constipation, vomiting, hypertension, abdominal pain, diarrhea, tachycardia, dizziness and reflux (US prescribing information for Cobenfy, 9/2024).

Is it approved in Europe?

On October 24, 2026, we did not find an authorized medicine page on the EMA website.

Final checklist

• I recorded why each previous antipsychotic was stopped.
• I investigated substance use and other causes of worsening.
• I asked about urinary retention, reflux, constipation and glaucoma.
• I measured liver enzymes and bilirubin and measured heart rate.
• I reviewed CYP2D6 inhibitors and other antimuscarinics.
• I explained the schedule away from meals and the titration.
• I warned about nausea and constipation in the first weeks.
• I arranged close appointments and monitoring of weight, blood glucose and lipids.

Want to practice reasoning with progressive clues? Play the case of the day.

References

1. Brannan SK, Sawchak S, Miller AC, et al. Muscarinic Cholinergic Receptor Agonist and Peripheral Antagonist for Schizophrenia. N Engl J Med. 2021. PMID 33626254.
2. Bristol Myers Squibb. COBENFY™ (xanomeline and trospium chloride) capsules, for oral use. Prescribing Information. Revised 9/2024. Accessed 24/10/2026. Official source.
3. Gerolymos C, Barazer R, Yon DK, et al. Drug Efficacy in the Treatment of Antipsychotic-Induced Akathisia: A Systematic Review and Network Meta-Analysis. JAMA Netw Open. 2024. PMID 38451521.
4. Hasan AH, Abid MA. Cobenfy (Xanomeline-Trospium Chloride): A New Frontier in Schizophrenia Management. Cureus. 2024. PMID 39525169.
5. Kaul I, Sawchak S, Walling DP, et al. Efficacy and Safety of Xanomeline-Trospium Chloride in Schizophrenia: A Randomized Clinical Trial. JAMA Psychiatry. 2024. PMID 38691387.
6. Kaul I, Sawchak S, Claxton A, et al. Efficacy of xanomeline and trospium chloride in schizophrenia: pooled results from three 5-week, randomized, double-blind, placebo-controlled, EMERGENT trials. Schizophrenia (Heidelb). 2024. PMID 39488504.
7. Pillinger T, McCutcheon RA, Vano L, et al. Comparative effects of 18 antipsychotics on metabolic function in patients with schizophrenia, predictors of metabolic dysregulation, and association with psychopathology: a systematic review and network meta-analysis. Lancet Psychiatry. 2020. PMID 31860457.
8. Pillinger T, Howes OD, Correll CU, et al. Antidepressant and antipsychotic side-effects and personalised prescribing: a systematic review and digital tool development. Lancet Psychiatry. 2023. PMID 37774723.
9. Ramey OL, Silva Almodóvar A. Xanomeline-Trospium: A Novel Therapeutic for the Treatment of Schizophrenia. Ann Pharmacother. 2025. PMID 40145363.
10. Smith CM, Augustine MS, Dorrough J, et al. Xanomeline-trospium (Cobenfy(TM)) for Schizophrenia: A Review of the Literature. Clin Psychopharmacol Neurosci. 2025. PMID 39820108.
11. U.S. Food and Drug Administration. Drugs@FDA: FDA-Approved Drugs. NDA 216158, Cobenfy. Accessed on 10/24/2026. Official source.
12. Żełabowski K, Pichowicz W, Dembowska J, et al. From dopamine to muscarine: xanomeline-trospium (KarXT) as a novel direction in the psychopharmacotherapy of schizophrenia. Front Pharmacol. 2026. PMID 41756233.