From the Guidelines
Doxepin is the preferred treatment for insomnia due to its FDA approval and efficacy in sleep maintenance issues at low doses, with a recommended dosage of 3-6 mg taken 30 minutes before bedtime. When considering the treatment of insomnia, it's essential to weigh the benefits and risks of various pharmacological options. According to the most recent and highest quality study 1, low-dose doxepin has been shown to improve sleep outcomes, including sleep latency, total sleep time, and sleep quality, with minimal adverse effects. In contrast, mirtazapine, while effective for sleep, is primarily an antidepressant with sedating effects as a secondary benefit, and its use for insomnia is not FDA-approved.
Some key points to consider when choosing between doxepin and mirtazapine for insomnia treatment include:
- Efficacy: Doxepin has been specifically studied and approved for insomnia treatment, whereas mirtazapine's primary indication is for depression.
- Dosage: Low-dose doxepin (3-6 mg) is recommended for insomnia, while mirtazapine's sedating effects are often stronger at lower doses (7.5-15 mg).
- Side effects: Both medications can cause side effects, but doxepin at low doses typically has fewer side effects, such as dry mouth, constipation, and dizziness.
- Concurrent conditions: The choice between doxepin and mirtazapine may depend on whether the patient has concurrent depression, which might favor mirtazapine, or primarily insomnia, which might favor doxepin.
It's also important to note that non-pharmacologic interventions, such as cognitive behavioral therapy for insomnia (CBT-I), are considered more effective than pharmacologic therapies for the treatment of chronic insomnia disorder, with fewer adverse effects 1. However, for patients who are unable or unwilling to receive CBT-I, a short course of low-dose doxepin or nonbenzodiazepine benzodiazepine receptor agonists (BZRAs) may be considered.
From the Research
Treatment Options for Insomnia
- Doxepin, a tricyclic antidepressant, has been shown to be effective in the treatment of insomnia, particularly in improving sleep maintenance and sleep duration 2, 3, 4.
- Mirtazapine, a tetracyclic antidepressant, has also been studied as a treatment for insomnia, with some evidence suggesting its effectiveness in reducing insomnia severity, particularly in patients with sleep maintenance problems 5, 6.
Efficacy of Doxepin
- Low-dose doxepin (3-6 mg) has been found to have a small to medium effect size against placebo for sleep maintenance and sleep duration, but not for sleep initiation 4.
- Doxepin has been shown to be safe and effective in improving sleep for 1-2 nights, with no significant next-day residual effect 4.
Efficacy of Mirtazapine
- Low-dose mirtazapine (7.5-15 mg) has been found to provide a statistically significant and clinically relevant reduction of insomnia severity at 6 weeks, but not at later time points 6.
- Mirtazapine has been shown to result in higher improvement and recovery rates compared to placebo at week 6, particularly in patients with sleep maintenance problems 6.
Comparison of Doxepin and Mirtazapine
- While both doxepin and mirtazapine have been found to be effective in the treatment of insomnia, the current evidence suggests that doxepin may be more effective in improving sleep maintenance and sleep duration 2, 3, 4.
- Mirtazapine, on the other hand, may be more effective in reducing insomnia severity, particularly in patients with sleep maintenance problems 5, 6.