What side effects should be monitored in a patient taking brexpiprazole (Rexulti) 3 mg?

Side Effects to Monitor for Rexulti (Brexpiprazole) 3 mg

When monitoring a patient on Rexulti 3 mg, prioritize surveillance for weight gain, akathisia, metabolic disturbances (hyperglycemia, dyslipidemia), sedation, and extrapyramidal symptoms, as these represent the most common and clinically significant adverse effects requiring regular assessment. 1

Critical Safety Monitoring (Highest Priority)

Metabolic Parameters

• Blood glucose: Check before starting or soon after initiation, then regularly during long-term treatment. Watch for symptoms of hyperglycemia (excessive thirst, hunger, urination, weakness, confusion, fruity breath odor) 1
• Lipid panel: Check before or soon after starting, then periodically during treatment 1
• Weight: Monitor at baseline and frequently throughout treatment. Expect mean weight gain of approximately 2.7 kg by 26 weeks and 3.2 kg by 52 weeks, with 25.8% of patients experiencing ≥7% weight increase 2

Movement Disorders

• Akathisia (restlessness, need to move): Most common extrapyramidal symptom, occurring in 6.7% of patients. Risk increases with 3 mg dose compared to 2 mg 2, 3
• Tardive dyskinesia: Uncontrolled movements of face, tongue, or body parts that may be irreversible. Can occur during treatment or after discontinuation 1
• Extrapyramidal symptoms: Monitor for difficulty moving, slow movement, tremors, muscle stiffness, and abnormal eye movements (particularly relevant in younger patients 13-17 years) 1

Cardiovascular Monitoring

• Orthostatic hypotension: Check blood pressure sitting and standing, especially during dose initiation. Patients may experience dizziness, lightheadedness, or syncope when rising 1
• Falls risk: Increased due to sedation, orthostatic hypotension, and motor impairment 1

Common Side Effects (Moderate Priority)

Neuropsychiatric

• Somnolence/sedation: Occurs in 8.0% of patients in long-term studies. Advise patients about operating machinery or driving 2
• Headache: Most common adverse event (7.2-8.0% incidence) 4, 2
• Insomnia: Paradoxically occurs in 6.3% despite sedating properties 2
• Cognitive function: Monitor for confusion or cognitive impairment, though studies show no worsening of cognition in dementia populations 4

Other Common Effects

• Increased appetite: 6.3% incidence, contributing to weight gain 2
• Fatigue: 6.1% of patients 2
• Upper respiratory infections: 5.4% incidence 2

Serious but Less Common Risks

Life-Threatening Conditions

• Neuroleptic malignant syndrome (NMS): Monitor for high fever, muscle rigidity, confusion, changes in vital signs, and increased sweating. This is a medical emergency 1
• Seizures: Assess seizure history and monitor for new-onset convulsions 1
• Cerebrovascular events: Particularly in elderly patients with dementia (0.5% incidence in studies), though not significantly different from placebo 4

Hematologic

• Leukopenia: Check white blood cell count during first few months of treatment 1

Behavioral

• Compulsive behaviors: Monitor for new or unusual urges (gambling, sexual urges, shopping, binge eating). Educate patients and families to report these immediately 1

Temperature Regulation

• Hyperthermia: Difficulty controlling body temperature, especially with strenuous exercise, heat exposure, dehydration, or anticholinergic medications 1

Swallowing

• Dysphagia: Can lead to aspiration pneumonia 1

Monitoring Schedule

Baseline: Weight, blood glucose, lipid panel, blood pressure (sitting/standing), movement disorder assessment, CBC

First 3 months: Monthly weight, movement disorder screening, CBC monitoring, assess for akathisia and sedation

Ongoing: Quarterly metabolic panels (glucose, lipids), weight checks, blood pressure monitoring, annual comprehensive movement disorder evaluation

Important Clinical Considerations

The 3 mg dose carries higher risk of akathisia and somnolence compared to 2 mg 3. Most adverse events are mild to moderate in severity, with discontinuation rates of 6.3% in clinical trials 2. The safety profile appears generally favorable in both psychiatric and dementia populations when monitored appropriately 4, 5.

Contraindication: Do not use in patients with known hypersensitivity to brexpiprazole (can cause rash, facial swelling, urticaria, anaphylaxis) 1.