Which medication, lamotrigine, Lyrica (pregabalin), or Seroquel (quetiapine), is most likely causing a patient's emotional lability and agitation?

Quetiapine (Seroquel) is Most Likely Causing Emotional Lability and Agitation

Among lamotrigine, Lyrica (pregabalin), and Seroquel (quetiapine), quetiapine is most likely causing the patient's emotional lability and agitation, as it is specifically documented to cause agitation as a common adverse effect.

Medication Analysis

Quetiapine (Seroquel)

• Documented agitation effects: The FDA drug label for quetiapine specifically lists agitation as a known adverse reaction 1
• Mechanism: As an atypical antipsychotic, quetiapine works by antagonizing both serotonin 5-HT2 and dopamine D2 receptors, which can paradoxically cause emotional disturbances 2
• Prevalence: Clinical guidelines note that quetiapine can cause anxiety (4% vs 3% on placebo) and agitation (2% vs 0% on placebo) 1
• Timing: These effects can occur at any point during treatment but may be more prominent during dose adjustments

Pregabalin (Lyrica)

• While pregabalin can cause mood disturbances, the FDA label indicates that agitation and restlessness are primarily seen in overdose situations, not at therapeutic doses 3
• Pregabalin is less commonly associated with emotional lability at standard dosing compared to quetiapine

Lamotrigine

• Lamotrigine has been associated with emotional disturbances in rare cases
• There are isolated case reports of anger with murderous impulse 4, but these are uncommon adverse effects
• Lamotrigine is actually often used to reduce mood lability in certain conditions 5

Diagnostic Algorithm

1. Assess temporal relationship:

   • Did symptoms begin or worsen after starting quetiapine or after a dose increase?
   • Have there been recent dose adjustments to any of the medications?

2. Evaluate symptom pattern:

   • Quetiapine-induced agitation often presents with restlessness, anxiety, and emotional changes
   • Look for other quetiapine side effects like somnolence, dizziness, or dry mouth that may be present

3. Consider medication interactions:

   • The combination of these medications may potentiate side effects
   • Quetiapine with pregabalin can increase CNS depression but may also cause paradoxical excitation

Management Recommendations

1. Consider quetiapine dose reduction or discontinuation:

   • If clinically appropriate, reduce the dose of quetiapine under medical supervision
   • Monitor for improvement in emotional lability and agitation

2. Alternative medication options:

   • If antipsychotic therapy is still needed, consider switching to an alternative with lower agitation risk
   • Olanzapine may be better tolerated in some patients with less agitation 6

3. Monitoring parameters:

   • Regularly assess for changes in emotional state and agitation levels
   • Watch for extrapyramidal symptoms which can accompany or be confused with agitation

Important Considerations

• Withdrawal caution: Never abruptly discontinue quetiapine as this can worsen symptoms
• Underlying conditions: Rule out other causes of emotional lability such as bipolar disorder exacerbation or neurological conditions
• Elderly patients: Older adults are particularly susceptible to medication-induced agitation and emotional changes 7
• Medication timing: Administering quetiapine at bedtime rather than during the day may help reduce daytime agitation

Quetiapine-induced agitation and emotional lability can significantly impact quality of life and medication adherence. Prompt recognition and management of these side effects is essential to improve patient outcomes and prevent unnecessary suffering.