Mirtazapine Dosing in Adolescents
For adolescents with depression, start mirtazapine at 7.5 mg once daily at bedtime, with gradual titration in 7.5 mg increments up to a maximum of 45 mg daily based on clinical response and tolerability. 1
Starting Dose and Titration Strategy
Begin with 7.5 mg once daily at bedtime in adolescent patients, which is lower than the typical adult starting dose of 15 mg 1
Increase dosage in 7.5 mg increments every 5-7 days as tolerated, monitoring for both therapeutic response and adverse effects 1
Maximum daily dose is 45 mg administered as a single bedtime dose or in divided doses throughout the day 1
Treatment duration in the pediatric study ranged from 11 to 368 days, with individualized titration based on target symptom response 1
Clinical Monitoring Requirements
Assess response within 1-2 weeks of reaching each dose level, as clinical improvement with mirtazapine typically occurs within 2-4 weeks at an effective dose 2
Monitor for common adverse effects including somnolence (which paradoxically may be more prominent at lower doses), increased appetite, weight gain, and sedation 3, 2
Evaluate sleep quality and anxiety symptoms early, as these may improve within the first week of treatment even before full antidepressant effects emerge 2, 4
Use standardized rating scales such as the Clinical Global Impression (CGI) scale to objectively track improvement in target symptoms 1
Important Clinical Considerations
The lower starting dose of 7.5 mg in adolescents (compared to 15 mg in adults) reflects increased sensitivity to adverse effects in younger patients. 1 This conservative approach allows for better tolerability while establishing therapeutic benefit.
Sedation is dose-dependent and often decreases at higher therapeutic doses (≥15 mg), so don't mistake initial sedation at 7.5 mg as a reason to stay at subtherapeutic doses 4
Once-daily bedtime dosing is preferred due to the 20-40 hour elimination half-life and the sedative properties that can be therapeutically useful for sleep disturbances 2, 5
In the autism spectrum disorder study, 16 of 17 adolescent patients showed significant improvement in sleep disorders and behavioral symptoms with mirtazapine titration 1
Dosing in Special Populations
Hepatic or renal impairment requires dose reduction and more cautious titration, as clearance decreases by approximately 30% with moderate impairment and 50% with severe renal impairment 5
Female adolescents may require lower doses than males due to higher plasma concentrations at equivalent doses 5
Common Pitfalls to Avoid
Don't stop at 7.5 mg assuming it's therapeutic - this is a starting dose for tolerability assessment, not typically an effective antidepressant dose 1
Don't increase doses too rapidly - allow 5-7 days between increments to assess both efficacy and tolerability 1
Don't combine with other sedating medications without careful monitoring, as additive CNS depression can occur 6
Monitor for paradoxical behavioral activation, which can occur in younger patients, particularly those with developmental disabilities 1