Can Mirtazapine Tablets Be Split in Half?
Yes, mirtazapine 15 mg and 30 mg tablets can be split in half because they are scored tablets specifically designed for splitting, while the 45 mg tablet cannot be split as it is unscored. 1
Tablet Formulations and Splitting Capability
The FDA-approved mirtazapine tablets come in three formulations with different splitting capabilities 1:
- 15 mg tablets: Pale yellow, oval-shaped, scored tablets imprinted "APO" on one side and "MI" bisect "15" on the other—can be split 1
- 30 mg tablets: Light pink, oval-shaped, scored tablets imprinted "APO" on one side and "MI" bisect "30" on the other—can be split 1
- 45 mg tablets: White to off-white, oval-shaped, unscored tablets imprinted "APO" on one side and "MI-45" on the other—should not be split 1
Clinical Rationale for Splitting
Splitting scored mirtazapine tablets is clinically appropriate for achieving lower starting doses, particularly the 7.5 mg dose. 2, 3
When to Use Half-Tablet (7.5 mg) Dosing:
- Elderly, debilitated, or frail patients should be considered for starting at 7.5 mg at bedtime 3
- Patients with documented extreme sensitivity to psychotropic medications may benefit from this lower starting dose 2
- Patients particularly sensitive to medication side effects can use 7.5 mg as a "test dose" strategy 2
Important Caveat About 7.5 mg Dosing:
Starting at 7.5 mg for 2 weeks may delay the onset of antidepressant action, essentially adding 2 weeks to the expected time to therapeutic benefit. 2 The standard therapeutic starting dose is 15 mg daily, with assessment of therapeutic response beginning within 1-2 weeks and adequate response evaluation requiring 6-8 weeks at therapeutic doses. 2, 3
Dosing Algorithm
For most patients:
- Start at 15 mg once daily at bedtime (full tablet) 4, 5
- Effective dosage range: 15-45 mg daily 4, 5
- Maximum recommended dose: 45 mg daily 3
For sensitive populations (elderly, frail, medication-sensitive):
- Start at 7.5 mg at bedtime (split 15 mg tablet) 3
- Increase to 15 mg after tolerability is established
- Continue titration as needed based on response
Pharmacokinetic Considerations
The elimination half-life of mirtazapine is 20-40 hours, which supports once-daily dosing and means that splitting tablets does not affect the pharmacokinetic profile. 4, 6 Steady state is reached in 4-6 days regardless of whether tablets are split. 6