In a patient with bipolar II disorder stabilized on lamotrigine who has comorbid anxiety, does buspirone cause weight gain?

Buspirone and Weight Gain

Buspirone is weight-neutral and does not cause weight gain, making it an excellent choice for managing anxiety in your patient with bipolar II disorder who is already stabilized on lamotrigine.

Weight Profile of Buspirone

• Buspirone is not mentioned in any of the comprehensive guideline reviews of medications associated with weight gain, which systematically catalog antidepressants, antipsychotics, mood stabilizers, and anxiolytics that affect weight 1, 2, 3
• The absence of buspirone from these extensive weight-gain medication lists indicates it is weight-neutral in clinical practice 1, 3

Compatibility with Your Current Regimen

• Lamotrigine itself is associated with weight loss rather than weight gain, and does not appear to cause bodyweight gain in bipolar disorder patients 2, 4, 3
• Lamotrigine is particularly effective for bipolar II disorder, with studies showing it may be more suitable for maintenance treatment in BPII than in BPI, especially for preventing depressive and hypomanic episodes 5, 6
• Adding buspirone to lamotrigine should not create additive weight gain concerns since both agents are weight-neutral 2, 4, 3

Medications to Avoid in Your Situation

If you were considering alternatives to buspirone for anxiety management, you should specifically avoid:

• Mirtazapine - closely associated with significant weight gain and would be particularly problematic 1, 3
• Paroxetine - has the highest risk of weight gain among all SSRIs 1, 3
• Benzodiazepines - while weight-neutral, they carry dependency risks and are generally less favorable for chronic anxiety management 3

Monitoring Recommendations

• Establish baseline weight and BMI before initiating buspirone 2
• Monitor weight monthly for the first 3 months, then quarterly during continued treatment 2
• This monitoring protocol applies to the overall psychiatric medication regimen rather than buspirone specifically, but maintains good clinical practice 2

Important Clinical Considerations

• Your patient's lamotrigine should be maintained at current dose since it provides mood stabilization for bipolar II disorder 5, 6
• Buspirone typically requires 2-4 weeks to achieve anxiolytic effects, so set appropriate expectations with your patient
• Unlike benzodiazepines, buspirone does not cause sedation or dependency, making it suitable for long-term anxiety management in bipolar disorder 3