Zispin
mirtazapine
Pharmacologic class: Piperazinoazepine derivative
Therapeutic class: Tetracyclic antidepressant
Pregnancy risk category C
FDA Box Warning
• Drug may increase risk of suicidal thinking and behavior in children and adolescents with major depressive disorder and other psychiatric disorders. Risk must be balanced with clinical need, as depression itself increases suicide risk. With patient of any age, observe closely for clinical worsening, suicidality, and unusual behavior changes when therapy begins. Advise family and caregivers to observe patient closely and communicate with prescriber as needed.
• Drug isn't approved for use in pediatric patients.
Action
Potentiates effects of norepinephrine and serotonin by blocking their synaptic reuptake. Also exerts anticholinergic activity by disrupting muscarinic receptors.
Availability
Tablets: 15 mg, 30 mg, 45 mg
Tablets (orally disintegrating): 15 mg, 30 mg, 45 mg
Indications and dosages
➣ Depression
Adults: Initially, 15 mg/day as a single dose at bedtime; may increase dosage q 1 to 2 weeks up to 45 mg/day. For maintenance, 15 to 45 mg/day.
Dosage adjustment
• Renal or hepatic impairment
• Elderly patients
Contraindications
• Hypersensitivity to drug
• MAO inhibitor use within past 14 days
Precautions
Use cautiously in:
• hepatic or renal impairment
• history of seizures, cardiovascular or cerebrovascular disease, or psychiatric illness
• elderly patients
• pregnant or breastfeeding patients
• children (safety not established).
Administration
• Administer orally disintegrating tablet without water. Have patient place it on tongue until it melts. Make sure tablet isn't broken.
• Be aware that drug is usually used in conjunction with psychotherapy.
See Don't give within 14 days of MAO inhibitors.
Adverse reactions
CNS: drowsiness, dizziness, abnormal dreams, abnormal thinking, asthenia, tremor, confusion, suicidal behavior or ideation (especially in child or adolescent)
CV: orthostatic hypotension, chest pain
EENT: sinusitis
GI: constipation, dry mouth
GU: urinary frequency, urinary tract infection
Hematologic: agranulocytosis
Musculoskeletal: back pain, myalgia
Respiratory: increased cough, dyspnea
Skin: photosensitivity
Other: flulike symptoms, edema, increased appetite, weight gain, increased thirst
Interactions
Drug-drug. Benzodiazepines, other CNS depressants: additive CNS depression
Drugs metabolized by CYP450 enzyme: altered metabolism of these drugs
MAO inhibitors: hypertension, seizures, death
Drug-diagnostic tests. Alanine aminotransferase, cholesterol, triglycerides: increased levels
Drug-herbs. Chamomile, hops, kava, skullcap, valerian: increased CNS depression
S-adenosylmethionine (SAM-e), St. John's wort: increased risk of serotonergic adverse effects (including serotonin syndrome)
Drug-behaviors. Alcohol use: additive CNS effects
Patient monitoring
• Monitor vital signs, especially for orthostatic hypotension.
• Assess neurologic status.
• Watch for weight gain caused by edema or increased appetite.
• Stay alert for urinary tract infection, sinusitis, and flulike symptoms.
See Monitor CBC with white cell differential. Stay alert for agranulocytosis.
See Watch for suicidal behavior or ideation (especially in child or adolescent).
Patient teaching
• Advise patient to take with food or milk to reduce GI upset.
• Tell patient he may crush conventional tablets if he can't swallow them whole.
• Instruct patient to take orally disintegrating tablet without water. Tell him to place it on tongue until it melts and to make sure tablet isn't broken.
• Advise patient that therapeutic effects may take 2 to 3 weeks.
See Tell patient to immediately report sore throat, fever, mouth sores, or other signs or symptoms of infection.
See Instruct patient (or parent) to immediately report suicidal thoughts or actions (especially in child or adolescent).
See Caution patient not to discontinue drug abruptly. Dosage must be tapered.
• If drug causes oversedation, tell patient to consult prescriber about taking entire daily dose at bedtime.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• Tell patient to avoid alcohol and to discuss herbal use with prescriber.
• Instruct patient to avoid exposure to excessive sunlight or sun lamps.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.