Can Buspar (buspirone) and Remeron (mirtazapine) be given together?

Combining Buspar (Buspirone) and Remeron (Mirtazapine)

Yes, Buspar (buspirone) and Remeron (mirtazapine) can be safely administered together as they work through different mechanisms and have complementary effects for treating anxiety and depression. 1, 2

Mechanism of Action and Rationale

• Buspirone acts primarily as a partial agonist at serotonin 5-HT1A receptors, with some affinity for dopamine D2 autoreceptors, providing anxiolytic effects without significant sedation or dependence issues 3
• Mirtazapine works as a noradrenergic and specific serotonergic antidepressant (NaSSA) that promotes sleep, appetite, and weight gain 1
• The combination targets different neurotransmitter systems, potentially providing more comprehensive symptom relief for patients with both anxiety and depression 2

Dosing Recommendations

• For buspirone: Start with 5 mg twice daily and gradually titrate up to a maximum of 20 mg three times daily as needed 2
• For mirtazapine: Begin with 7.5 mg at bedtime and gradually increase to an effective dose, typically 15-30 mg at bedtime 1
• When combining these medications, start with lower doses of each and titrate gradually while monitoring for side effects 2

Benefits of This Combination

• Mirtazapine can help address sleep disturbances and appetite issues often present in anxiety and depression 1
• Buspirone provides anxiolytic effects without the risk of dependence, tolerance, or withdrawal associated with benzodiazepines 2, 3
• Unlike benzodiazepines, buspirone does not cause cognitive impairment or paradoxical agitation, making it suitable for long-term anxiety management 2
• The combination may be particularly helpful for patients with comorbid anxiety and depression who haven't responded adequately to monotherapy 2

Potential Side Effects and Monitoring

• Common side effects of buspirone include headaches, dizziness, nervousness, and lightheadedness 3
• Mirtazapine commonly causes sedation, increased appetite, and weight gain 1
• Monitor for potential serotonergic effects, although the risk of serotonin syndrome with this specific combination is low compared to combinations with SSRIs 2, 4
• Be aware that buspirone takes 2-4 weeks to reach full therapeutic effect, unlike benzodiazepines which work more rapidly 2, 3

Important Considerations

• Buspirone has a short half-life (approximately 2-3 hours) and is extensively metabolized, with low bioavailability (about 4%) 5
• Mirtazapine is potent at promoting sleep and weight gain, which may be beneficial for patients with insomnia or poor appetite 1
• Neither medication carries significant risk for dependence or withdrawal symptoms, making them suitable for longer-term treatment 2, 3

Potential Drug Interactions

• While there are theoretical concerns about serotonergic effects when combining multiple serotonergic agents, this specific combination has not been associated with significant adverse interactions 2
• Caution is advised when adding other serotonergic medications to this regimen 4, 6
• Food increases the bioavailability of buspirone approximately 2-fold, so consistent administration with respect to meals is recommended 5

Common Pitfalls to Avoid

• Expecting immediate anxiolytic effects from buspirone - unlike benzodiazepines, buspirone requires several weeks for full therapeutic effect 2, 3
• Discontinuing either medication abruptly - although withdrawal syndromes are less common than with other psychotropics, gradual tapering is still recommended 2
• Using buspirone for acute severe anxiety where it may not be effective enough - it's better suited for generalized anxiety disorder than panic or acute severe anxiety 2, 3

This combination represents a rational approach for patients with both anxiety and depression, particularly when sleep disturbance is a prominent symptom, as mirtazapine's sedative effects complement buspirone's non-sedating anxiolytic properties 1, 2.