What is the starting dose of Remeron (mirtazapine) for adults with major depressive disorder?

Starting Dose of Mirtazapine for Major Depressive Disorder

The recommended starting dose of mirtazapine for adults with major depressive disorder is 15 mg once daily, administered orally, preferably in the evening prior to sleep. 1

Dosing Guidelines

• The initial dose should be 15 mg taken as a single dose at bedtime 1, 2
• If patients do not have an adequate response to the initial 15 mg dose, the dose can be increased up to a maximum of 45 mg per day 1
• Dose changes should not be made in intervals of less than 1-2 weeks to allow sufficient time for evaluation of response to a given dose 1, 3
• The effective daily dosage range is 15-45 mg 4

Clinical Considerations for Dosing

• Mirtazapine has a long elimination half-life of 20-40 hours, which enables once-daily bedtime dosing 4
• The sedative effects of mirtazapine are more pronounced at lower doses (15 mg) and may decrease at higher doses 3
• Mirtazapine is particularly effective for patients with depression accompanied by sleep disturbances, as it promotes sleep 5
• The medication is also beneficial for patients with depression accompanied by poor appetite, as it promotes appetite and weight gain 5

Special Populations

• In older adults, lower starting doses are often recommended (approximately 50% of the adult starting dose) due to greater risk of adverse drug reactions 2
• Dosage adjustments may be needed in patients with renal or hepatic impairment 1, 3

Drug Interactions

• A decrease in mirtazapine dosage may be needed with concomitant use of strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin) 1
• An increase in mirtazapine dosage may be needed with concomitant use of strong CYP3A inducers (e.g., carbamazepine, phenytoin, rifampin) 1
• At least 14 days must elapse between discontinuation of a monoamine oxidase inhibitor (MAOI) antidepressant and initiation of mirtazapine 1

Common Side Effects

• The most common adverse effects include somnolence, increased appetite, weight gain, and dizziness 6
• Sedation is often beneficial for patients with insomnia but may be problematic for others 5
• Weight gain should be monitored, especially in patients concerned about weight 5

Onset of Action

• Clinical effect typically begins in 2-4 weeks, similar to other antidepressants 4
• Sleep disturbances and anxiety symptoms may improve in the first week of treatment 4, 7

Discontinuation

• When discontinuing mirtazapine, gradually reduce the dosage rather than stopping abruptly to minimize withdrawal symptoms 1

By starting with 15 mg once daily at bedtime and carefully titrating the dose based on response and tolerability, clinicians can optimize the therapeutic benefits of mirtazapine while minimizing adverse effects.