What is the recommended dosing and counseling for a patient starting mirtazapine (Remeron)?

Mirtazapine (Remeron) Dosing and Patient Counseling

The recommended starting dose of mirtazapine is 15 mg once daily, administered orally in the evening prior to sleep, with titration up to 30-45 mg daily as needed for optimal antidepressant effect. 1, 2

Dosing Recommendations

• Initial dose: 15 mg once daily at bedtime 1
• Titration: Dose changes should not be made in intervals of less than 1-2 weeks to allow sufficient time for evaluation of response 1
• Effective dose range: 15-45 mg daily 1, 2
• Sedation effects:
  • Lower doses (7.5-15 mg) tend to be more sedating due to predominant H1 receptor antagonism 2
  • Higher doses (30-45 mg) have optimal antidepressant effects 2

Mechanism of Action and Effects

• Mirtazapine increases noradrenergic and serotonergic neurotransmission via blockade of central α2-adrenergic receptors 3
• It blocks postsynaptic 5-HT2 and 5-HT3 receptors, which helps minimize certain side effects 3
• Onset of clinical antidepressant effect typically occurs in 2-4 weeks 3
• Sleep disturbances and anxiety symptoms may improve within the first week of treatment 3

Patient Counseling Points

1. Administration timing: Take in the evening before bedtime to minimize daytime sedation 1, 2

2. Common side effects:

   • Sedation/drowsiness (54%) - most pronounced at lower doses 2, 3
   • Increased appetite (17%) 2
   • Weight gain (10%) 2
   • Dry mouth (25%) 2

3. Monitoring needs:

   • Assess therapeutic response after 4-8 weeks 2
   • Monitor sleep quality, daytime sedation, weight changes, and mood symptoms 2
   • Regular monitoring of blood pressure, weight, and metabolic parameters 2

4. Drug interactions:

   • Avoid MAOIs - at least 14 days must elapse between discontinuing MAOIs and starting mirtazapine, and vice versa 1
   • Strong CYP3A inducers (e.g., carbamazepine, phenytoin, rifampin) may require mirtazapine dose increase 1
   • Strong CYP3A inhibitors (e.g., ketoconazole, clarithromycin) may require mirtazapine dose decrease 1

5. Discontinuation:

   • Do not stop abruptly - gradually reduce the dosage to minimize withdrawal effects 1
   • Treatment should continue for 4-9 months after satisfactory response for first episode of depression 2

Special Populations

• Elderly patients: May require lower starting doses (7.5-15 mg) due to reduced clearance 2
• Hepatic/renal impairment: Dose adjustments may be required 2
• Bipolar disorder: Screen patients for personal or family history of bipolar disorder before starting treatment 1

Safety Profile

• Mirtazapine has minimal cardiovascular and anticholinergic effects 3
• Lacks typical SSRI-related side effects like gastrointestinal symptoms and sexual dysfunction 3
• Appears safe in overdose with primarily sedation reported 3
• Rare cases of agranulocytosis and neutropenia have been reported 2

Common Pitfalls to Avoid

1. Starting at too high a dose - may increase side effect burden unnecessarily
2. Abrupt discontinuation - can lead to withdrawal symptoms
3. Missing the paradoxical effect of dosing - lower doses (15 mg) are often more sedating than higher doses (30-45 mg)
4. Failure to screen for bipolar disorder - antidepressants can trigger manic episodes
5. Combining with MAOIs - can lead to serotonin syndrome