Overview
DESCRIPTION Pimozide, USP is an orally active antipsychotic agent of the diphenyl-butylpiperidine series. The structural formula of pimozide, 1-[1-[4,4-bis(4-fluorophenyl)butyl]-4-piperidinyl]-1,3- dihydro-2H-benzimidazole-2-one is: The solubility of pimozide in water is less than 0.01 mg/mL; it is slightly soluble in most organic solvents.
Mechanism of Action
CLINICAL PHARMACOLOGY Pharmacodynamic Actions Pimozide tablets are an orally active antipsychotic drug product which shares with other antipsychotics the ability to blockade dopaminergic receptors on neurons in the central nervous system. Although its exact mode of action has not been established, the ability of pimozide to suppress motor and phonic tics in Tourette’s Disorder is thought to be a function of its dopaminergic blocking activity. However, receptor blockade is often accompanied by a series of secondary alterations in central dopamine metabolism and function which may contribute to both pimozide’s therapeutic and untoward effects.
Indications
- INDICATIONS & USAGE Pimozide tablets are indicated for the suppression of motor and phonic tics in patients with Tourette’s Disorder who have failed to respond satisfactorily to standard treatment. Pimozide tablets are not intended as a treatment of first choice nor is it intended for the treatment of tics that are merely annoying or cosmetically troublesome. Pimozide tablets should be reserved for use in Tourette’s Disorder patients whose development and/or daily life function is severely compromised by the presence of motor and phonic tics.
Common Doses
- 0.05 mg
- 0.2 mg
- 10 mg
- 2 mg
Dosage
DOSAGE & ADMINISTRATION General The suppression of tics by pimozide tablets requires a slow and gradual introduction of the drug. The patient’s dose should be carefully adjusted to a point where the suppression of tics and the relief afforded is balanced against the untoward side effects of the drug. An ECG should be done at baseline and periodically thereafter, especially during the period of dose adjustment (see WARNINGS and PRECAUTIONS - Laboratory Tests ).
Contraindications
- CONTRAINDICATIONS Pimozide is contraindicated in the treatment of simple tics or tics other than those associated with Tourette’s Disorder. Pimozide should not be used in patients taking drugs that may, themselves, cause motor and phonic tics (e.g., pemoline, methylphenidate and amphetamines) until such patients have been withdrawn from these drugs to determine whether or not the drugs, rather than Tourette’s Disorder, are responsible for the tics.
Side Effects
- ADVERSE REACTIONS General Extrapyramidal Reactions: Neuromuscular (extrapyramidal) reactions during the administration of pimozide have been reported frequently, often during the first few days of treatment. In most patients, these reactions involved Parkinson-like symptoms which, when first observed, were usually mild to moderately severe and usually reversible. Other types of neuromuscular reactions (motor restlessness, dystonia, akathisia, hyperreflexia, opisthotonos, oculogyric crises) have been reported far less frequently.
Interactions
- DRUG INTERACTIONS Because pimozide prolongs the QT interval of the electrocardiogram, an additive effect on QT interval would be anticipated if administered with other drugs, such as phenothiazines, tricyclic antidepressants or antiarrhythmic agents, which prolong the QT interval. Accordingly, pimozide should not be given with dofetilide, sotalol, quinidine, other Class Ia and III anti-arrhythmics, mesoridazine, thioridazine, chlorpromazine, droperidol, sparfloxacin, gatifloxacin, moxifloxacin, halofantrine, mefloquine, pentamidine, arsenic trioxide, levomethadyl acetate, dolasetron mesylate,...