Pimozide

Trade Names:
Orap
- Tablets 1 mg
- Tablets 2 mg

Pharmacology

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Blockage of dopaminergic receptors on neurons in the CNS.

Pharmacokinetics

Absorption

More than 50% of oral dose absorbed. T _max is 6 to 8 h.

Metabolism

Significant first-pass metabolism by N-dealkylation in the liver, catalyzed mainly by CYP3A enzymatic system and to a lesser extent by CYP1A2 producing 2 major metabolites of undetermined activity.

Elimination

Primarily in the kidney, small amount in feces. Serum t _½ is approximately 55 h.

Indications and Usage

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 or inhibit CYP3A4; patients with hypokalemia or hypomagnesemia; patients receiving aprepitant or the azole antifungal agents itraconazole, ketoconazole, and voriconazole; patients receiving the macrolide antibiotics azithromycin, clarithromycin, dirithromycin, erythromycin, and troleandomycin; patients receiving protease inhibitors (eg, amprenavir, atazanavir, indinavir, nelfinavir, ritonavir, saquinavir); coadministration of nefazodone, sertraline, zileuton, or ziprasidone; severe toxic CNS depression or comatose states from any cause; hypersensitivity to pimozide.

Dosage and Administration

PO For the initial dose, give 1 to 2 mg/day in divided doses, increasing the dose every other day. For the maintenance dose, give less than 0.2 mg/kg/day or 10 mg/day, whichever is less. Doses greater than 0.2 mg/kg/day or 10 mg/day are not recommended.

PO For the initial dose, give 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).

Storage/Stability

Store at controlled room temperature (59° to 86°F).

Drug Interactions

Pimozide may potentiate effects of these agents.

Coadministration with pimozide is contraindicated.

Coadministration of these agents with pimozide is contraindicated.

Coadministration of these agents with pimozide is contraindicated.

May increase pimozide concentration, increasing the pharmacologic and adverse reactions. Avoid grapefruit juice and grapefruit products.

Laboratory Test Interactions

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; hyperpyrexia; opisthotonos; tardive dyskinesia; NMS (NMS); Parkinsonian syndrome; grand mal seizures; drowsiness; sedation; insomnia; rigidity; speech disorder; handwriting change; akinesia; depression; excitement; nervousness; adverse behavior; headache; abnormal dreaming; hyperkinesia; somnolence; torticollis; limb tremor; dizziness.

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.

Genitourinary

Menstrual disorder; breast secretions; impotence; nocturia; urinary frequency; loss of libido.

Miscellaneous

Sudden, unexpected death; hyperpyrexia; muscle cramps and tightness; stooped posture; asthenia; myalgia; chest pain; periorbital edema.

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Children

Limited information regarding use, efficacy, and safety in patients younger than 12 yr of age.

Renal Function

Use with caution.

Hepatic Function

Use with caution.

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.

NMS

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.

Sudden death

Sudden, unexpected deaths have occurred in patients receiving dosages in the range of 1 mg/kg. Prolongation of the QT interval, predisposing patients to ventricular arrhythmia, is one possible mechanism for the deaths. Ensure ECG is performed before initiating therapy and periodically thereafter, especially during periods of dose adjustment. Ensure hypokalemia and hypomagnesemia are corrected before initiating therapy and normal potassium and magnesium 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.

Tardive dyskinesia

This syndrome of potentially irreversible, involuntary dyskinetic movements has occurred with other antipsychotic agents. Incidence appears to be highest among the elderly, especially women.

Overdosage

Symptoms

Severe extrapyramidal reactions, ECG abnormalities, hypotension, comatose state with respiratory depression.

Patient Information

• Explain name, dose, action, and potential side effects of drug, including risk of developing tardive dyskinesia.
• Advise patient that dose may be increased slowly until max 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.
• Advise patient to notify health care provider of the following: excessive drowsiness, change in behavior, rapid pulse.
• Advise patient that if a decision to withdraw therapy is made, not to 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 to keep appointments.

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