Mesoridazine

A to Z Drug Facts

 Actions Blocks dopamine receptor in CNS.

 Indications Management of schizophrenia in patients who fail to respond adequately to treatment with other antipsychotic agents.

 Contraindications Congenital QT interval prolongation; concurrent drugs that prolong the QT interval; history of cardiac arrhythmias; severe CNS depression or comatose states (including drug-induced CNS depression); hypersensitivity to mesoridazine.

 Route/Dosage

Because of potentially serious side effects, usethe minimal effective dose.

ADULTS: PO Start with 50 mg tid (optimal dose range, 100 to 400 mg/day).

ADULTS: IM Start with 25 mg and repeat in 30 to 60 min, if necessary (optimal dosage range, 25 to 200 mg/day).

 Interactions

Alcohol and other CNS depressants: May result in increased CNS depression and may precipitate extrapyramidal reaction. Anticholinergics: May reduce therapeutic effects of mesoridazine and worsen anticholinergic effects of mesoridazine. May lead to tardive dyskinesia. Drugs that prolong the QT interval: May increase the risk of life-threatening cardiac arrhythmias (including torsades de pointes).

 Lab Test Interferences None well documented.

 Adverse Reactions

CARDIOVASCULAR: Hypotension; prolongation of QTc interval, which is associated with life-threatening cardiac arrhythmias; ventricular arrhythmias; changes in terminal portion of ECG. CNS: Drowsiness; tremor; muscular rigidity; Parkinson syndrome; dizziness; weakness; restlessness; ataxia; slurring; akathisia; fainting; agitation; motor restlessness; dystonic reactions; trismus; torticollis; opisthotonos; oculogyric crises; tardive dyskinesia, bizarre dreams; aggravation of psychoses; toxic confessional state. DERMATOLOGIC: Itching; rash; hypertrophic papilla of tongue; angioneurotic edema; erythema; exfoliative dermatitis; contact dermatitis. EENT: Stuffy nose; photophobia; blurred vision; miosis; tardive dyskinesia; discoloration of sclera and cornea; opacities of the anterior lens and cornea. GI: Dry mouth; nausea; vomiting; constipation; anorexia; paralytic ileus; obstipation. GU: Inhibition of ejaculation; impotence; enuresis; incontinence; priapism; menstrual irregularities; altered libido; gynecomastia; lactation; urinary retention. HEMATOLOGIC: Agranulocytosis; leukopenia; eosinophilia; thrombocytopenia; anemia; aplastic anemia; pancytopenia. HEPATIC: Jaundice; biliary stasis. METABOLIC: Weight gain. OTHER: Fever; laryngeal edema; angioneurotic edema; asthma; edema; hyperpyrexia; systemic lupus erythematosus-like syndrome.

 Precautions

Pregnancy: Safety and efficacy not established. Lactation: Undetermined. CHILDREN: Safety and efficacy not established. Neuroleptic malignant syndrome: Has occurred with this class of agents; potentially life-threatening. Signs and symptoms include hyperpyrexia, muscle rigidity, altered mental status, irregular pulse and blood pressure, tachycardia, and diaphoresis. QT interval: The QT and QTc interval are prolonged in a dose-related fashion, which may cause serious ventricular arrhythmias (including torsades de pointes). Tardive dyskinesia: May occur with this class of agents and may become irreversible, depending on the duration of treatment and total cumulative dose. The syndrome consists of involuntary, dyskinetic movements.

 Administration/Storage

• Administer tablets or oral concentrate in divided doses, tid.
• Measure prescribed dose of oral concentrate using measuring dropper supplied with bottle.
• Oral concentrate may be diluted with distilled water, orange juice, or grape juice just prior to administration. Do not prepare dilutions ahead of time and store.
• Injection is for IM administration only. Not for IV, SC, or intradermal administration.
• IM dose may be repeated in 30 to 60 min if necessary.
• Store tablets and injection below 86°F. Store oral solution below 77°F. Protect oral solution and injection from light.

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note history of the following: allergy to mesoridazine or other phenothiazines, cardiac arrhythmias, bradycardia, hypokalemia, congenital QT interval prolongation, concomitant use of other drugs which prolong the QT interval, or previous episodes of Neuroleptic Malignant Syndrome.
• Ensure that baseline ECG is performed and serum potassium level is determined before starting therapy and periodically during treatment.
• Do not administer to patient with QTc interval greater than 450 msec at baseline. Discontinue therapy if QTc interval prolongs to greater than 500 msec during therapy.
• Inform physician immediately if hyperpyrexia, muscle rigidity, altered mental status, irregular pulse and BP, tachycardia, and diaphoresis develop.
• Notify health care provider immediately if palpitations or syncope occur.
• Assess neurologic status before and during treatment. Observe for involuntary body and facial movements, excessive drowsiness, agitation, tremor, or anxiety. Inform health care provider if noted.
• Administer IM to patient who is bedfast. Keep patient lying down for at least 30 min after injection to minimize hypotensive effects.
• Assess medication compliance.

 Patient/Family Education

• Explain name, dose, action, and potential side effects of drug.
• Instruct patient, family, or caregiver to measure prescribed dose of oral concentrate using measuring dropper supplied with bottle.
• Advise patient, family, or caregiver that oral concentrate may be diluted with distilled water, orange juice or grape juice just prior to administration. Caution to not prepare dilutions ahead of time and store.
• Instruct patient to not stop taking mesoridazine when they feel better.
• Instruct patient, family, or caregiver to immediately report fainting or loss of consciousness, palpitations, dizziness, high fever, muscle rigidity, altered mental status, irregular pulse, or unexplained sweating to health care provider.
• Advise patient to avoid strenuous activity during periods of high temperature or humidity.
• Instruct patient to avoid alcoholic beverages.
• Instruct patient to get up slowly from lying or sitting position and to avoid sudden position changes to prevent postural hypotension. Advise patient to report dizziness with position changes to health care provider. Caution patient that hot tubs and hot showers or baths may make dizziness worse.
• Advise patient to take sips of water, suck on ice chips or sugarless hard candy, or chew sugarless gum if dry mouth occurs.
• Advise patient that drug may cause drowsiness and to use caution while driving or performing other tasks requiring mental alertness.
• Instruct women to notify health care provider if pregnant, planning to become pregnant, or breastfeeding.
• Advise patient, family, or caregiver to notify health care provider of: excessive drowsiness, increased agitation or anxiety, or involuntary body or facial movements.
• Instruct patient to not take any prescription or OTC medications or dietary supplements unless advised to do so by their health care provider.
• Advise patient that follow-up visits may be required to monitor therapy and keep appointments.

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