Cobenfy (KarXT) is a drug approved by the U.S. FDA in 2024 for the treatment of schizophrenia in adults. As a fixed-dose combination of xanomeline (a muscarinic agonist) and trospium chloride (a muscarinic antagonist), it can improve symptoms while also posing risks that require strict monitoring.

What Are the Side Effects of Cobenfy (KarXT)?

Common Side Effects

Gastrointestinal Symptoms: Nausea (19%), dyspepsia (18%), vomiting (15%), constipation (17%), abdominal pain (8%), diarrhea (6%), and gastroesophageal reflux disease (5%).

Cardiovascular System: Hypertension (11%), tachycardia (6%), and orthostatic hypotension (2%).

Nervous System: Dizziness (6%), somnolence (3%), and blurred vision (3%).

Others: Dry mouth (4%), hypersalivation (2%), cough (2%), and extrapyramidal symptoms excluding akathisia (2%).

Watch for Severe Side Effects of Cobenfy (KarXT)

Risk of Urinary Retention

High-Risk Populations: Elderly patients, individuals with bladder outlet obstruction (e.g., benign prostatic hyperplasia), and patients with diabetic cystopathy.

Clinical Manifestations: Hesitancy in urination, weak urine stream, feeling of incomplete bladder emptying, and painful urination.

Countermeasures: Monitor symptoms; adjust the dose or discontinue the drug if necessary. Urinary catheterization may be required in severe cases.

Severe Allergic Reactions

Angioedema: May involve the face, lips, tongue, and larynx, and can occur with the first dose.

Management Principles: Discontinue the drug immediately, initiate emergency medical support, and ensure airway patency.

Hepatobiliary System Injury

Manifestations: Elevated liver enzymes (incidence of ALT/AST > 3 times the upper limit of normal is 2.8%), which may be accompanied by biliary spasm and pancreatitis.

Contraindicated Populations: Contraindicated in patients with moderate to severe liver impairment (Child-Pugh Class B/C).

Central Nervous System Effects

Symptoms: Dizziness, confusion, hallucinations, and somnolence.

Precautions: Avoid driving or operating heavy machinery during treatment.

Precautions for Using Cobenfy (KarXT)

Contraindicated Populations

Patients with urinary retention or gastric retention.

Patients with moderate to severe liver impairment and untreated angle-closure glaucoma.

Patients allergic to Cobenfy or trospium chloride.

Administration Method and Timing

Dosing Timing: Take at least 1 hour before a meal or at least 2 hours after a meal.

Capsule Handling: Do not open the capsules; they must be swallowed whole.

Management of Drug Interactions

Strong CYP2D6 Inhibitors (e.g., paroxetine): May increase the plasma concentration of xanomeline; closely monitor for adverse reactions.

Drugs Secreted via Renal Tubules (e.g., metformin): Competitive excretion may exacerbate side effects of both drugs.

Other Anticholinergic Drugs: Concomitant use may enhance reactions such as dry mouth and constipation.