What is the recommended starting dose of mirtazapine (Remeron) for adults?

Mirtazapine Starting Dose for Adults

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

Initial Dosing Protocol

• Begin with 15 mg once daily at bedtime as the standard starting dose for all adults 1, 2, 3
• Evening administration is specifically recommended to leverage the drug's sedative properties, which can help address sleep disturbances that commonly accompany depression 4
• The 15 mg starting dose should be maintained for at least 1-2 weeks before considering dose adjustments 1

Dose Titration Strategy

• If inadequate response occurs after 1-2 weeks at 15 mg, increase the dose up to a maximum of 45 mg per day 1
• Dose changes should not be made in intervals shorter than 1-2 weeks to allow sufficient time for evaluation of therapeutic response 1
• The effective daily dosage range is 15-45 mg, with most patients responding within this range 2, 3

Timeline for Clinical Response

• Begin assessing therapeutic response and adverse effects within 1-2 weeks of treatment initiation 5
• Sleep disturbances and anxiety symptoms may improve within the first week of treatment, though full antidepressant effect typically requires 2-4 weeks 2, 6
• If the patient does not have an adequate response within 6-8 weeks, treatment modification is strongly recommended 5

Special Clinical Considerations

• Mirtazapine is particularly effective for patients with depression accompanied by insomnia, anorexia, or weight loss due to its sedating properties and appetite-stimulating effects 5
• The drug has a faster onset of action than some SSRIs (fluoxetine, paroxetine, sertraline) 5
• Exercise caution in patients with obstructive sleep apnea, as mirtazapine may worsen this condition 4

Common Pitfalls to Avoid

• Do not start below 15 mg - some older literature suggested starting at lower doses, but current FDA labeling clearly establishes 15 mg as the appropriate starting dose 1
• Do not increase doses too rapidly - allow the full 1-2 weeks between dose adjustments to properly assess response 1
• Screen for bipolar disorder before initiating treatment, as antidepressants can precipitate manic episodes in susceptible patients 1
• Gradually taper rather than abruptly discontinue to minimize withdrawal symptoms 1

Drug Interactions Requiring Dose Modification

• Decrease mirtazapine dose when co-administering with strong CYP3A4 inhibitors (ketoconazole, clarithromycin) or cimetidine 1
• Increase mirtazapine dose when co-administering with strong CYP3A inducers (carbamazepine, phenytoin, rifampin) 1
• Allow at least 14 days between discontinuing an MAOI and starting mirtazapine, and vice versa 1

Expected Side Effects at Starting Dose

• Somnolence/sedation is common and may actually be more pronounced at lower doses 2, 6
• Increased appetite and weight gain occur more frequently than with placebo 2, 3
• Dry mouth is a common side effect 5
• The drug has minimal cardiovascular, anticholinergic, and sexual dysfunction side effects compared to tricyclic antidepressants and SSRIs 2, 6