Should the mirtazapine dose be adjusted and can cabergoline help with sexual function given the patient's medication history and side effects?

Mirtazapine Dosage Adjustment and Sexual Function Management

For this patient, maintaining the mirtazapine dose at 11.25mg is recommended, as lower doses (7.5-15mg) are more sedating and can help with sleep while discontinuing doxepin, but cabergoline is not recommended for sexual dysfunction management.

Mirtazapine Dosage Considerations

Mirtazapine is a unique antidepressant with both noradrenergic and specific serotonergic effects. According to FDA labeling, the recommended starting dose is 15mg once daily, preferably in the evening prior to sleep 1. However, several important factors apply to this specific patient:

• The patient has been taking mirtazapine for years at 7.5mg and recently increased to 11.25mg
• They are discontinuing doxepin 6mg (likely used for sleep)
• Lower doses of mirtazapine (7.5-15mg) tend to be more sedating due to predominant H1 receptor antagonism 2
• Higher doses (30-45mg) have stronger antidepressant effects but less sedation 2

Optimal Dosing Strategy

For this patient:

• Maintain at 11.25mg rather than increasing to 15mg or decreasing to 7.5mg
• Rationale: This intermediate dose will help maintain sleep benefits while discontinuing doxepin, without increasing to a dose that might be less sedating
• The American Academy of Family Physicians notes that mirtazapine at 7.5-15mg is effective for promoting sleep, appetite, and weight gain 3

Sexual Dysfunction Management

The patient is switching from vortioxetine 5mg to bupropion 75mg to address sexual function issues. However:

• Bupropion has caused multiple side effects in this patient (sweating, constipation, thirst, irritability, insomnia, anger) at doses above 75mg
• The patient is inquiring about cabergoline for sexual function

Recommendation for Sexual Dysfunction

1. Do not use cabergoline for sexual dysfunction

   • Cabergoline is primarily indicated for hyperprolactinemia and inhibition of lactation 4
   • It is not FDA-approved or recommended in guidelines for sexual dysfunction
   • Potential risks include nausea, vomiting, headache, dizziness, and possible cardiovascular effects

2. Continue bupropion at 75mg

   • Bupropion is weight-neutral or associated with weight loss and has fewer sexual side effects compared to other antidepressants 3
   • At the current 75mg dose, the patient appears to tolerate it without the side effects experienced at higher doses

3. Mirtazapine and sexual function

   • Mirtazapine has minimal serotonergic side effects such as sexual dysfunction 5
   • The combination of low-dose mirtazapine with low-dose bupropion may provide adequate antidepressant effect with minimal sexual side effects

Sleep Management

Since the patient is discontinuing doxepin 6mg and used zolpidem CR 6.25mg:

• Maintaining mirtazapine at 11.25mg will help with sleep due to its sedative properties at lower doses 2
• The sedative effects of mirtazapine are most pronounced at lower doses (7.5-15mg) 3
• Avoid regular use of zolpidem CR due to potential for tolerance and dependence

Monitoring Recommendations

1. Assess therapeutic response after 4-8 weeks on the current regimen
2. Monitor for:
   • Sleep quality and daytime sedation
   • Sexual function improvement
   • Weight changes (mirtazapine can increase appetite and weight)
   • Mood and anxiety symptoms

Important Considerations

• Dose changes should not be made in intervals less than 1-2 weeks to allow sufficient time for evaluation 1
• If sleep remains problematic despite mirtazapine at 11.25mg, consider non-pharmacological sleep hygiene interventions before increasing the dose
• If sexual dysfunction persists, maintaining bupropion at 75mg (where tolerated) is preferable to adding cabergoline

The combination of mirtazapine at 11.25mg and bupropion at 75mg provides a balanced approach that addresses sleep issues while minimizing sexual side effects, without introducing medications like cabergoline that aren't indicated for this purpose.