Should we increase Pristiq (desvenlafaxine) or add Buspar (buspirone) for a patient with Parkinson's disease, anxiety, and currently on Ativan (lorazepam) and Carbidopa/Levodopa?

Management of Anxiety in a Patient with Parkinson's Disease

Adding buspirone (Buspar) is the preferred approach for managing anxiety in this patient with Parkinson's disease who is currently on Pristiq 50 mg, Ativan, and carbidopa-levodopa.

Rationale for Adding Buspirone

Buspirone is particularly suitable for this patient for several reasons:

• Buspirone is indicated for the management of anxiety disorders and has shown efficacy in patients with coexisting depressive symptoms 1
• Buspirone can be safely used in Parkinson's disease without worsening parkinsonian symptoms 2
• Adding buspirone rather than increasing Pristiq (desvenlafaxine) is preferable because:
  1. Augmentation strategies with buspirone have shown effectiveness for anxiety symptoms 3
  2. Buspirone has a favorable side effect profile compared to increasing the SNRI dose
  3. Buspirone may have additional benefits in Parkinson's disease, including potential reduction in levodopa-induced dyskinesias 2

Dosing Recommendations

• Start buspirone at a low dose of 5 mg twice daily 4
• Titrate slowly based on response and tolerability
• Maximum dosage can reach up to 20 mg three times daily if needed 4
• For this patient with Parkinson's disease, consider a more conservative approach with slower titration and lower target doses

Monitoring Considerations

1. Motor symptoms: Monitor for any worsening of Parkinson's symptoms, although studies suggest buspirone does not typically worsen parkinsonism 2, 5

2. Sedation: Watch for additive sedation since the patient is already on Ativan (lorazepam) 4

3. Orthostatic hypotension: Monitor blood pressure, particularly when standing, as this is a potential side effect 4

4. Onset of action: Inform the patient that buspirone may take 2-4 weeks to become fully effective for anxiety symptoms 4

5. Drug interactions: Be aware that buspirone is metabolized by CYP3A4, so any medications that affect this enzyme system may alter buspirone levels 1

Cautions and Considerations

• Anxiety is often undertreated in Parkinson's disease, with one study showing over 50% of non-depressed PD patients with clinically significant anxiety receiving no medication treatment 6

• In a trial of buspirone for anxiety in Parkinson's disease, the median tolerated dose was 7.5 mg twice daily, lower than typical doses in non-PD patients 5

• Some patients (53%) in the buspirone trial experienced adverse events related to motor function, suggesting careful monitoring is needed 5

• Consider that the patient is already on Ativan (lorazepam), which may be causing some dependence; buspirone could eventually help facilitate tapering of the benzodiazepine if appropriate

Alternative Approaches

If buspirone is not tolerated or ineffective:

1. Then consider increasing Pristiq from 50 mg to 75 mg or 100 mg

2. Consider non-pharmacological approaches like cognitive behavioral therapy

3. Evaluate for motor fluctuations that may be contributing to anxiety, as these are associated with anxiety symptoms in Parkinson's disease 6