mirtazapine (Rx)

Brand and Other Names:Remeron, Remeron SolTab
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Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

tablet

  • 7.5mg
  • 15mg
  • 30mg
  • 45mg

disintegrating tablet

  • 15mg
  • 30mg
  • 45mg

Depression

Indicated for treatment of major depressive disorder

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

Dosage Modifications

Renal impairment (CrCl <39 mL/min): Clearance is reduced; monitor closely

Hepatic impairment: Clearance is reduced; monitor closely

Safety and efficacy not established

Depression

Indicated for treatment of major depressive disorder

Initiate with lower dose for patients aged ≥65 yr

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

Dosing Considerations

Geriatric patients may have reduced clearance of mirtazapine and, as a result, may have increased plasma levels of the drug

Use with caution

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Interactions

Interaction Checker

and mirtazapine

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    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

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            Adverse 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

            Arrythmia Torsades de Pointes

            Hyperprolactenemia and related symptoms galactorrhea and gynecomastia

            Sonambulism (complex behaviors)

            Severe skin reactions

            • Stevens-Johnson syndrome
            • Bullous dermatitis
            • Erythema multiforme
            • Toxic epidermal necrolysis
            • Increased creatine kinase blood levels
            • Rhabdomyolysis
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            Warnings

            Black Box Warnings

            In short-term studies, antidepressants increased the risk of suicidal thinking and behavior in children, adolescents, and young adults (aged <24 years) taking antidepressants for major depressive disorders and other psychiatric illnesses

            This increase was not seen in patients aged ≥24 years

            A slight decrease in suicidal thinking was seen in adults aged ≥65 years compared with placebo

            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

            Patients with major depressive disorder (MDD), both adult and pediatric, may experience worsening of their depression and/or the emergence of suicidal ideation and behavior (suicidality) or unusual changes in behavior, whether or not they are taking antidepressant medications, and this risk may persist until significant remission occurs

            Screen for bipolar disorder; MDD episode may be the initial presentation of bipolar disorder; generally believed (though not established in controlled trials) that treating such an episode with an antidepressant alone may increase precipitation of mixed/manic episode in patients at risk for bipolar disorder

            Rare reports of activation of mania/hypomania

            Agranulocytosis reported; if sign/symptoms develop (eg, sore throat, fever, stomatitis, infection with low WBC count), discontinue mirtazapine and closely monitor

            Potentially life-threatening serotonin syndrome reported with SNRIs and SSRIs alone, but also if coadministered with other serotonergic drugs

            Pupillary dilation that occurs with antidepressant drugs may trigger an angle-closure attack in patients with anatomically narrow angles who have not had iridectomy

            Upon discontinuation (particularly when abrupt), the following symptoms may occur: dizziness, abnormal dreams, sensory disturbances (including paresthesia and electric shock sensations), agitation, anxiety, fatigue, confusion, headache, tremor, nausea, vomiting, and sweating

            Akathisia, characterized by subjectively unpleasant or distressing restlessness and need to move, often accompanied by an inability to sit or stand still; most likely to occur within first few weeks; increasing dose may be detrimental

            Hyponatremia (rare) reported

            Somnolence reported in ~50% of patients

            Dizziness, increased appetite/weight gain, and transaminase elevations reported

            Postmarketing reports of QT prolongation, torsades de pointes, ventricular tachycardia, and sudden death; majority reported in association with overdose or in patients with other risk factors for QT prolongation, including concomitant use of QTc-prolonging medicines

            Drug interaction overview

            • Caution if coadministered with other drugs that prolong QT interval
            • Monitor INR if higher doses of mirtazapine are coadministered with warfarin
            • Avoid use with alcohol and other CNS depressants; may cause additive somnolence and dizziness
            Risk of serotonin syndrome
            • Contraindicated with MAOIs; do not start mirtazapine if being treated with IV methylene blue or linezolid
            • Caution with other serotonergic drugs
            CYP inducers
            • Strong CYP inducers (eg, phenytoin, carbamazepine, rifampin) may increase mirtazapine clearance by ~2-fold
            • If coadministered with strong CYP inducers, mirtazapine dose may need to be increased; conversely, if strong CYP inducer is stopped, decrease mirtazapine dose
            Strong CYP3A4 inhibitors
            • Strong CYP3A4 inhibitor increase mirtazapine peak plasma levels and AUC
            • Caution if coadministered; mirtazapine dose may need to be lowered
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            Pregnancy & Lactation

            Pregnancy

            There are no adequate and well-controlled studies in pregnant women

            Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed

            Animal studies

            • Reproduction studies in pregnant rats and rabbits at doses up to 100 mg/kg and 40 mg/kg, respectively (20 and 17 times the maximum recommended human dose [MRHD] on an mg/m2 basis, respectively), have revealed no evidence of teratogenic effects
            • However, in rats, there was an increase in postimplantation losses in dams treated with mirtazapine

            Lactation

            May be excreted in breast milk; caution advised

            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.

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            Pharmacology

            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%)

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            Administration

            Oral Administration

            May take with or without food

            Storage

            Store at 20-25ºC (68-77ºF); excursions permitted to 15-30ºC (59-86ºF)

            Protect from light and moisture

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            Formulary

            FormularyPatient Discounts

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            The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

            Tier Description
            1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
            2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
            3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
            4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
            NC NOT COVERED – Drugs that are not covered by the plan.
            Code Definition
            PA Prior Authorization
            Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
            QL Quantity Limits
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            Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
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            Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.