mirtazapine (Remeron, Remeron SolTab)
Classes: Antidepressants, Other; Antidepressants, Alpha-2 Antagonists
Dosing and uses of Remeron, Remeron SolTab (mirtazapine)
Adult dosage forms and strengths
tablet
- 7.5mg
- 15mg
- 30mg
- 45mg
disintegrating tablet
- 15mg
- 30mg
- 45mg
Depression
15 mg PO qHS; may increase no more frequently than q1-2Weeks; not to exceed 45 mg qHs
Post-traumatic Stress Disorder (Off-label)
15 mg PO qHS; may increase no more frequently than q1-2Weeks; not to exceed 60 mg qHs
Hot Flashes (Off-label)
7.5-60 mg PO qDay
Insomnia (Off-label)
15-45 mg PO qHs
Dosing Modifications
Renal impairment (CrCl <39 mL/min): Clearance is reduced; monitor closely
Hepatic impairment: Clearance is reduced; monitor closely
Pediatric dosage forms and strengths
Safety and efficacy not established
Geriatric dosage forms and strengths
Depression
7.5 mg/day PO qHS; increase by 7.5-15 mg/day no more frequently than q1-2Weeks; not to exceed 45 mg/day
Alzheimer Dementia-related Depression
7.5 mg/day PO qHS; increase by 7.5-15 mg/day no more frequently than q1-2Weeks; not to exceed 60 mg/day
Dosing Considerations
The elderly have reduced clearance of mirtazapine and, as a result, may have increased plasma levels of the drug
Use with caution
Remeron, Remeron SolTab (mirtazapine) adverse (side) effects
>10%
Somnolence (54%)
Weight gain (>7% increase in <49% of pediatric patients)
Xerostomia (25%)
Increased appetite (17%)
Constipation (13%)
1-10%
Asthenia (8%)
Weakness (8%)
Weight gain (>7% increase in 8% of adults)
Dizziness (7%)
Serum TGs increased (6%)
Dream disorder (4%)
Disturbance in thinking (3%)
ALT increased (2%)
Peripheral edema (2%)
Myalgia (2%)
Confusion (2%)
Urinary frequency (2%)
Tremor (2%)
Back pain (2%)
Dyspnea (1%)
<1%
Mania (0.2%)
Grand mal seizure (less than 0.1%)
Frequency not defined
Depression exacerbation
Status epilepticus
Suicidal thoughts, suicide (rare)
Agranulocytosis
Neutropenia
Postmarketing Reports
Severe skin reactions
- Stevens-Johnson syndrome
- Bullous dermatitis
- Erythema multiforme
- Toxic epidermal necrolysis
- Increased creatine kinase blood levels
- Rhabdomyolysis
Warnings
Black box warnings
In short-term studies, antidepressants increased the risk of suicidal thinking and behavior in children, adolescents, and young adults (<24 years) taking antidepressants for major depressive disorders and other psychiatric illnesses
This increase was not seen in patients >24 years
A slight decrease in suicidal thinking was seen in adults >65 years
In children and young adults, risks must be weighed against the benefits of taking antidepressants
Patients should be monitored closely for changes in behavior, clinical worsening, and suicidal tendencies
This should be done during the initial 1-2 months of therapy and dosage adjustments; the patient’s family should communicate any abrupt changes in behavior to the healthcare provider
Worsening behavior and suicidal tendencies that are not part of the presenting symptoms may require discontinuation of therapy
This drug is not approved for use in pediatric patients
Contraindications
Hypersensitivity
Within 14 days of administration of MAOIs (serotonin syndrome)
Patients receiving linezolid or methylene blue IV
Cautions
Start slowly in hepatic or renal dysfunction and in the elderly
Clinical worsening and suicidal ideation may occur despite medication
Rare reports of serotonin syndrome, particularly when coadministered with other serotonergic drugs
Abrupt discontinuation may cause dizziness, abnormal dreams, sensory disturbances (including paresthesia and electric shock sensations), agitation, anxiety, fatigue, confusion, headache, tremor, nausea, vomiting, and sweating
Bone fractures reported with therapy; consider possibility of fragility fracture if patient complains of bone pain, swelling, or bruising
Akathisia and psychomotor restlessness associated with antidepressant use
Rare reports of hyponatremia; caution in elderly or if coadministered with other drug known to cause hyponatremia
Risk for potentially life-threatening serotonin syndrome and neuroleptic malignant syndrome-like reactions has been reported with SSRIs, SNRIs, MAOIs, and other serotonergic drugs used as monotherapy, but particularly with concomitant use of the following agents: serotonergic drugs (including triptans), drugs that impair metabolism of serotonin (including MAOIs), antipsychotics, dopamine antagonists, and nonpsychiatric MAOIs (eg, linezolid, IV methylene blue)
May cause anticholinergic effects; use with caution in patients with xerostomia, BPH, paralytic ileus, or decreased intestinal motility
Risk of mydriasis; may trigger angle closure attack in patients with angle closure glaucoma with anatomically narrow angles without a patent iridectomy
May increase serum triglycerides and cholesterol levels
May cause orthostatic hypotension (low risk); use with caution in patients at risk
Sexual dysfunction may occur (incidence lower compared to SSRIs)
May worsen psychosis in some patients or precipitate mania or hypomania in patients with bipolar disorder
Use with caution in patients with history of seizures, head trauma, alcoholism, brain damage, and patients on medictions that may lower seizure treshold
QTc prolongation, ventricular fibrillation, and torsade de pointes rarely reported; use caution in patients with history of QTc prolongation, receiving QTc prolongent agents concomitantly, or with cardiovascular disease
Discontinue therapy if neutropenia/agrunolocytosis occur
May cause CNS depression, which may impair abilities to perform hazardous tasks that require mental alertness
May increase serum cholesterol and triglyceride levels
May increase appetite and cause weight gain
Pregnancy and lactation
Pregnancy category: C
Lactation: Avoid
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Remeron, Remeron SolTab (mirtazapine)
Mechanism of action
Tetracyclic structure different from SSRIs, TCAs and MAOIs; through its central presynaptic alpha2-adrenergic antagonist effects, stimulates norepinephrine and serotonin release; potent antagonist of 5-HT2 and 5-HT3 serotonin and histamine receptors; is a moderate alpha1 adrenergic and muscarinic antagonist
Absorption
Bioavailability: 50%
Peak serum time: 2 hr
Distribution
Protein bound: 85%
Vd: 4.5 L/kg
Metabolism
Hepatic CYP450 enzymes CYP1A2, CYP2D6, CYP3A4
Metabolites: Inactive
Elimination
Half-life: 20-40 hr
Excretion: Urine (75%); feces (15%)