What should be done if a patient with bipolar disorder develops slurred speech after starting Latuda (lurasidone) and Buspirone in addition to Topiramate (topiramate)?

Managing Slurred Speech in a Patient with Bipolar Disorder on Multiple Medications

Topiramate should be tapered and discontinued first as it is the most likely cause of slurred speech in this medication combination. 1

Understanding the Clinical Situation

The patient is currently taking three medications for bipolar disorder:

• Topiramate (Topamax)
• Lurasidone (Latuda)
• Buspirone

Slurred speech has developed after the addition of Latuda and buspirone to the existing topiramate regimen.

Medication Assessment and Action Plan

1. Topiramate (First to Address)

• Primary concern: Topiramate is the most likely culprit for slurred speech
• Evidence: FDA labeling identifies cognitive/neuropsychiatric adverse effects including speech disorders as common side effects 1
• Specific issues: Topiramate can cause:
  • Speech or language problems, particularly word-finding difficulties
  • Cognitive-related dysfunction
  • Confusion and psychomotor slowing
  • Paresthesia (tingling of extremities)
• Action: Begin tapering topiramate immediately rather than abrupt discontinuation
  • Gradual dose reduction is necessary to prevent seizure risk 1
  • Typical taper: Reduce by 25-50mg per week until discontinued

2. Lurasidone (Second Consideration)

• Generally well-tolerated with fewer neurological side effects compared to other antipsychotics 2
• Somnolence is a common side effect which could contribute to slurred speech
• Less likely to be the primary cause but may be contributing
• Can be maintained while topiramate is being tapered

3. Buspirone (Least Likely Cause)

• Not typically associated with slurred speech
• Generally has a favorable side effect profile
• Maintain current dosing while addressing topiramate

Monitoring During Medication Changes

1. Immediate assessment:

   • Check for other neurological symptoms (ataxia, nystagmus, confusion)
   • Evaluate hydration status (topiramate can cause dehydration)
   • Monitor for metabolic acidosis (a known complication of topiramate)

2. During topiramate taper:

   • Monitor speech function every 1-2 weeks
   • Watch for emergence of bipolar symptoms as medication is reduced
   • Assess for withdrawal symptoms

3. After topiramate discontinuation:

   • If speech normalizes: Consider alternative mood stabilizers if needed
   • If speech problems persist: Evaluate lurasidone next

Alternative Medication Options

If additional mood stabilization is needed after topiramate discontinuation:

• Valproic acid: Effective mood stabilizer, weight neutral 3
• Lamotrigine: Weight neutral alternative 3
• Lithium: Traditional mood stabilizer option

Important Considerations and Pitfalls

1. Never stop topiramate abruptly - this can precipitate seizures even in patients without epilepsy 1

2. Drug interactions: Topiramate can interact with other medications, potentially altering their blood levels and effects 1

3. Hydration status: Topiramate can cause decreased sweating and increased body temperature, especially in hot weather 1

4. Cognitive effects: "Word-finding difficulties" are a known side effect of topiramate that can manifest as slurred speech 4, 5

5. Monitoring for bipolar symptoms: As topiramate is tapered, watch closely for emergence of manic or depressive symptoms

By addressing the most likely culprit (topiramate) first through careful tapering, while maintaining the newer medications that may be providing important mood stabilization, this approach maximizes the chance of resolving the speech issues while maintaining control of the bipolar disorder.