Mirtazapine

A to Z Drug Facts

 Action Unknown. May enhance central nonadrenergic and serotonergic activity.

 Indications Treatment of depression.

 Contraindications Hypersensitivity to maprotiline or mirtazapine; concomitant use with MAO inhibitors.

 Route/Dosage

ADULTS: PO Initial dose: 15 mg/day as single dose. May be increased to 45 mg/day.

 Interactions

Alcohol, CNS depressants: Additive CNS effects. MAO inhibitors: May precipitate hypertensive crisis and convulsions with possible fatal results. Do not use mirtazapine in combination with an MAOI, or within 14 days of starting or stopping therapy with an MAOI.

 Lab Test Interferences None well documented.

 Adverse Reactions

CV: Hypotension; vasodilation; hypertension. CNS: Somnolence; asthenia; dizziness; abnormal dreams; abnormal thinking; remor; confusion; hypesthesia; apathy; depression; hypokinesis; twitching; gitation; anxiety; amnesia; hyperkinesia; paresthesia. DERM: Pruritis; rash. GI: Nausea; dry mouth; constipation; vomiting; appetite changes; abdominal pain. GU: Urinary frequency. HEMA: Agranulocytosis; leukopenia; thrombocytopenia; anemia. META: Weight gain. EENT: Sinusitis. RESP: Cough; dyspnea. OTHER: “Flu-like” syndrome; back pain; myasthenia; myalgia; arthralgia; eripheral edema; thirst.

 Precautions

Pregnancy: Category C. Lactation: Undetermined. Children: Safety and efficacy not established. Elderly: Use with caution. Special risk patients: Use with caution in patients with known cardiovascular or cerebrovascular disease that could be exacerbated by hypotension (history of MI, angina or ischemic stroke) and conditions that would predispose patients to hypotension dehydration, hypovolemia, treatment with antihypertensive agents). Renal function impairment: Use with caution. Hepatic function impairment: Use with caution. Transaminase elevations may occur without symptoms of compromised liver function. Severe depression: Closely supervise during initial drug therapy. Do not allow patient to possess more than small quantities of drug. Increased appetite/weight gain: Increases in appetite and weight gain have been reported. Cholesterol/triglycerides: Increases have been reported. Agranulocytosis: Has occurred. Warn patients about risk and symptoms of agranulocytosis.

 Administration/Storage

• Administer as a single daily dose, preferably in the evening prior to sleep.
• May be administered without regard to food.
• Dosage changes should be made in no less than 1–2 week intervals.
• Store at room temperature. Protect from light and moisture.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note history of sensitivity to drug or maprotiline, MI, angina and concomitant or recent use of MAOIs.
• Monitor patient's mood and affect closely. If mood changes or suicidal tendencies develop, notify physician and institute suicide precautions.
• Assess patient for side effects. Notify physician if present.
• If constipation occurs, increase fiber and fluid intake and mobility.

 Patient/Family Education

• Explain that full effectiveness of the drug may take several weeks to develop.
• Advise patient to take as a single dose in the evening prior to sleep.
• Instruct patient that if a dose is missed, it should be taken as soon as possible unless close to time of next dose.
• Warn patient not to double up doses and to notify physician if more than one dose is missed.
• Advise patient not to change the dose or discontinue the medication without consulting with their physician.
• Warn patient that drug may impair judgment, thinking and particularly, motor skills, because of prominent sedative effect and that this may impair their ability to drive, use machines or perform tasks that require alertness, coordination or physical dexterity.
• Caution patient about engaging in hazardous activities until they are reasonably certain that the drug does not affect their ability to engage in such activities.
• Advise patient to avoid alcohol and other CNS depressants because of additive impairment of cognitive and motor skills.
• Advise patient to inform their physician if they are taking, or intend to take any prescription or otc drugs because of the potential for interactions with mirtazapine.
• Advise female patients to notify their physician or pharmacist if they become pregnant or intend to become pregnant or are breastfeeding while taking this drug.
• Warn patient about the risk of developing agranulocytosis and to contact their physician if they experience any indication of infection eg, “flu-like” symptoms, fever, chills, sore throat, mucous membrane ulceration).
• Explain that drug may cause dry mouth and constipation. Advise patient about measures to manage these side effects.
• Advise patient to report these symptoms to physician: excessive sedation; dizziness; abnormal dreams or thinking; tremors; confusion; anxiety; gitation; rash; itching; excessive dry mouth; severe constipation.

Books@Ovid
Copyright © 2003 Facts and Comparisons
David S. Tatro
A to Z Drug Facts