Is Remeron (mirtazapine) safe for older adults?

Safety of Mirtazapine in Older Adults

Mirtazapine can be used safely in older adults, but requires careful dosing and monitoring due to increased risk of sedation, confusion, and potential for hyponatremia.

Efficacy and Use in Older Adults

Mirtazapine is a tetracyclic antidepressant that works as a noradrenergic and specific serotonergic antidepressant (NaSSA) by antagonizing α2-adrenergic receptors and blocking 5-HT2 and 5-HT3 receptors 1. It has established efficacy for:

• Depression in older adults
• Insomnia in older adults
• Depression with comorbid anxiety and sleep disturbances

A recent randomized controlled trial specifically in older adults (MIRAGE study) demonstrated that mirtazapine at 7.5mg significantly reduced chronic insomnia symptoms compared to placebo, with a mean reduction in Insomnia Severity Index of -6.5 points versus -2.9 points in the placebo group 2.

Dosing Recommendations for Older Adults

The FDA label and clinical guidelines recommend:

• Starting dose: 7.5mg at bedtime (lower than standard adult starting dose) 3
• Maximum dose: 30mg at bedtime 4
• Dose selection should be conservative, starting at the low end of the dosing range 3

Safety Considerations

Pharmacokinetic Changes

• Mirtazapine is substantially excreted by the kidney (75%) 3
• Decreased clearance occurs in elderly patients 3
• Steady-state concentrations take longer to reach in older adults (6 days vs. 4 days in younger adults) 3

Adverse Effects to Monitor

1. Sedation: Most common side effect, can be beneficial for insomnia but may cause daytime drowsiness 4
2. Confusion and over-sedation: Higher risk in elderly patients 3
3. Hyponatremia: Elderly patients may be at greater risk 3
4. Weight gain: Promotes appetite and weight gain 4, 1
5. Dry mouth: Common side effect 1

Comparative Safety

When compared to other medications sometimes used for similar indications in older adults:

• Mirtazapine has fewer anticholinergic effects than tricyclic antidepressants 4
• Unlike SSRIs, mirtazapine has minimal sexual side effects 1
• A recent study found mirtazapine had lower risk of mortality and falls compared to quetiapine when used for insomnia in older adults 5

Monitoring Recommendations

For older adults taking mirtazapine:

1. Monitor for excessive sedation, confusion, and cognitive impairment
2. Check sodium levels periodically to detect hyponatremia
3. Monitor weight changes
4. Assess renal function before and during treatment
5. Consider dose reduction after 9 months to reassess need for medication 4

Special Populations

Renal Impairment

• Dosage decrease is necessary in moderate to severe renal impairment 3
• More frequent monitoring of adverse effects is recommended 3

Hepatic Impairment

• Dosage decrease is necessary in moderate to severe hepatic impairment 3
• Clearance is reduced in patients with hepatic dysfunction 3

Conclusion

Mirtazapine can be used safely in older adults, particularly for those with depression and sleep disturbances. The key to safe use is appropriate dosing (starting at 7.5mg at bedtime), careful monitoring for adverse effects, and consideration of individual patient factors such as renal and hepatic function. When used appropriately, mirtazapine offers advantages over some alternatives, particularly for older adults who need both antidepressant effects and sleep improvement.