Pimozide

A to Z Drug Facts

 Actions Blockage of dopaminergic receptors on neurons in the CNS.

 Indications Suppression of motor and phonic tics in patients with Tourette syndrome who fail to respond satisfactorily to standard treatment.

 Contraindications Treatment of simple tics or tics other than those associated with Tourette syndrome; drug-induced motor and phonic tics (eg, amphetamine, methylphenidate, pemoline) until it is determined whether the tics are caused by drugs or Tourette syndrome; patients with congenital long QT syndrome, history of cardiac arrhythmias; administration with other drugs that prolong the QT interval; patients receiving the azole antifungal agents itraconazole and ketoconazole; patients receiving the macrolide antibiotics azithromycin, clarithromycin, dirithromycin, erythromycin, and troleandomycin; patients receiving protease inhibitors (eg, indinavir, nelfinavir, ritonavir, saquinavir); coadministration of nefazodone; severe toxic CNS depression or comatose states from any cause; hypersensitivity to pimozide.

 Route/Dosage

ADULTS: PO Initial dose: 1 to 2 mg/day in divided doses, increasing the dose every other day. Maintenance dose: Less than 0.2 mg/kg/day or 10 mg/day, whichever is less.

CHILDREN (at least 12 yr): PO Initial dose: 0.05 mg/kg/day (preferably at bedtime); increasing the dose every third day (max, 0.2 mg/kg, not to exceed 10 mg/day).

 Interactions

Drugs that prolong the QT interval (eg, azole antifungal agents [eg, ketoconazole], macrolide antibiotics [eg, erythromycin], nefazodone, phenothiazines [eg, thioridazine], protease inhibitors [eg, indinavir] tricyclic antidepressants [eg, amitriptyline], voriconazole, zileuton, ziprasidone): Increased risk of life-threatening cardiac arrhythmias, including torsades de pointes. Coadministration of these agents with pimozide is contraindicated. Drugs that may cause motor and phonic tics (eg, amphetamine, methylphenidate, pemoline): Coadministration of these agents with pimozide is contraindicated. Grapefruit juice: May increase pimozide concentrations, increasing the pharmacologic and adverse effects. Avoid grapefruit juice.

 Lab Test Interferences None well documented.

 Adverse Reactions

CARDIOVASCULAR: ECG changes, including prolongation of QT interval, flattening, notching, and inversion of T wave and appearance of U waves; postural hypotension; hypotension; hypertension; tachycardia; palpitations. CNS: Extrapyramidal reactions; motor restlessness; dystonia; akathisia; hyperreflexia; opisthotonos; tardive dyskinesia; neuroleptic malignant syndrome; Parkinson syndrome; grand mal seizures; drowsiness; sedation; insomnia; rigidity; speech disorder; handwriting change; akinesia; depression; excitement; nervousness; adverse behavior; headache; abnormal dreaming; hyperkinesias; somnolence; torticollis; limb tremor. DERMATOLOGIC: Rash; increased sweating; skin irritation. EENT: Oculogyric crises; visual disturbances; taste change; sensitivity of eyes to light; decreased accommodation; spots before eyes; blurred vision; cataracts. GI: Dry mouth; diarrhea; constipation; thirst; increased appetite; dysphagia; increased salivation; nausea; vomiting; anorexia; GI distress. GU: Menstrual disorder; breast secretions; impotence; nocturia; urinary frequency. OTHER: Sudden, unexpected death; hyperpyrexia; muscle cramps and tightness; stooped posture; asthenia; myalgia; chest pain; periorbital edema.

 Precautions

Pregnancy: Category C. LACTATION: Undetermined. CHILDREN: Information regarding use, efficacy, and safety in patients less than 12 yr limited. Impaired liver or kidney function: Use with caution. Neuroleptic malignant syndrome: This potentially fatal condition has been reported in association with antipsychotic agents. Signs and symptoms include hyperpyrexia, muscle rigidity, altered mental status, irregular pulse or BP, tachycardia, diaphoresis, cardiac arrhythmias. Tardive dyskinesia: This syndrome of potentially irreversible, involuntary dyskinetic movements has occurred with other antipsychotic agents. Incidence appears to be highest among the elderly. Special risk patients: Use with caution in patients with conditions that may be aggravated by anticholinergic activity, patients receiving anticonvulsant medication, patients with history of seizures or EEG abnormalities.

 Administration/Storage

• Administer prescribed dose bid to adults.
• Administer prescribed dose qd at bedtime to children.
• Have patient swallow whole. Do not crush, chew, or open capsules.
• Store at controlled room temperature (59° to 86°F).

 Assessment/Interventions

• Obtain patient history, including drug history and any known allergies. Note history of hypersensitivity to antipsychotic drugs, liver disease, kidney disease, congenital long QT syndrome, cardiac arrhythmias, previous episodes of neuroleptic malignant syndrome, seizures, or current use of anticonvulsants, pemoline, methylphenidate, amphetamines, macrolide antibiotics, protease inhibitors, azole antifungals, or drugs that prolong the QT interval.
• Ensure that baseline electrolytes are determined before starting therapy in patients taking diuretics.
• Ensure that ECG is performed before initiating therapy and periodically thereafter, especially during periods of dose adjustment. Ensure that hypokalemia is corrected before initiating therapy and normal potassium levels are maintained during therapy.
• Withhold therapy if QTc interval prolongs beyond 0.47 sec (children), 0.52 sec (adults), or more than 25% above baseline QTc.
• Inform health care provider immediately if hyperpyrexia, muscle rigidity, altered mental status, irregular pulse and BP, tachycardia, or diaphoresis develop.
• Notify health care provider immediately if palpitations or syncope occur.
• Assess baseline neurologic status and during treatment observe for involuntary body and facial movements, excessive drowsiness, behavior changes, and seizure activity. Inform health care provider if noted.
• Assess and document effect of medication on motor and phonic tic activity.
• Assess medication compliance.

 Patient/Family Education

• Explain name, dose, action, and potential side effects of drug.
• Advise patient that dose may be increased slowly until maximum benefit is achieved and not to take more than prescribed or increase the dose more rapidly than advised.
• Instruct patient not to stop taking pimozide when symptoms improve.
• Tell patient to immediately report fainting or loss of consciousness, palpitations, high fever, muscle rigidity, involuntary body or facial movements, altered mental status, irregular pulse, sweating, or seizures to health care provider.
• Advise patient to avoid strenuous activity during periods of high temperature or humidity.
• Instruct patient to avoid alcoholic beverages, grapefruit juice, and grapefruit products.
• 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 impair mental or physical abilities and to use caution while driving or performing other tasks requiring mental alertness.
• Instruct women to notify health care provider if pregnant, planning on becoming pregnant, or are breastfeeding
• Advise patient to notify health care provider of the following: excessive drowsiness, change in behavior, or rapid pulse.
• Instruct patient to not take any prescription or OTC medications or dietary supplements unless advised by health care provider.
• Advise patient that if a decision to withdraw therapy is made to not stop the medication suddenly. Gradual withdrawal over several days to weeks may be necessary to prevent withdrawal symptoms.
• Advise patient that follow-up visits and lab tests, including ECGs, will 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