What is the starting dose of mirtazapine (Remeron)?

Starting Dose of Mirtazapine

The recommended starting dose of mirtazapine is 15 mg once daily, administered orally, preferably in the evening prior to sleep. 1

Standard Dosing Protocol

• Initial dose: 15 mg once daily at bedtime 2, 1, 3
• This starting dose of 15 mg may produce therapeutic effects in some patients, with expected steady-state plasma concentrations of 7.3 ± 3.2 ng/mL 2
• The therapeutic range is established as 15-45 mg/day 2

Dose Titration Strategy

• If patients do not have an adequate response after 6-8 weeks at the initial 15 mg dose, increase to 30 mg daily 2, 1
  • Expected steady-state plasma concentrations at 30 mg: 18 ± 7 ng/mL 2
• Maximum approved dose is 45 mg per day 2, 1
  • Expected steady-state plasma concentrations at 45 mg: 28 ± 12 ng/mL 2
• Dose changes should not be made in intervals of less than 1 to 2 weeks to allow sufficient time for evaluation of response 1

Special Population Considerations

Elderly Patients

• Consider a lower initial dose (approximately 50% of the standard adult dose) in elderly patients due to higher risk of adverse reactions 2

Hepatic or Renal Impairment

• A dose reduction should be considered in patients with renal or hepatic impairment 2

Clinical Advantages of This Dosing

• Mirtazapine has an elimination half-life of 20-40 hours, enabling once-daily bedtime dosing 3, 4
• The drug demonstrates a faster onset of action than some SSRIs (fluoxetine, paroxetine, sertraline), with sleep disturbances and anxiety symptoms potentially improving in the first week of treatment 5, 3
• It is particularly suitable for patients with depression accompanied by insomnia or weight loss, as it promotes sleep, appetite, and weight gain 5, 6

Common Pitfalls to Avoid

• Do not start with subtherapeutic doses below 15 mg, as increased sedation is paradoxically more common at lower doses 7
• Ensure adequate trial duration: Begin assessing therapeutic response within 1-2 weeks, but allow 6-8 weeks before modifying treatment for inadequate response 5
• Screen for bipolar disorder prior to initiating treatment, as with all antidepressants 1

Expected Side Effects at Starting Dose

• Common side effects include somnolence/sedation, increased appetite, weight gain, dry mouth, and constipation or diarrhea 5, 3
• These effects are generally well-tolerated and may be beneficial in patients with depression-related insomnia or weight loss 5, 6