"The US Food and Drug Administration (FDA) has approved an extended-release capsule formulation of carbidopa-levodopa (Rytary, IPX066, Impax Pharmaceuticals) for the treatment of Parkinson's disease (PD), postencephalitic parkinsonism, an"...
Patients to be treated with ARTANE (trihexyphenidyl) should have a gonioscope evaluation prior to initiation of therapy and close monitoring of intraocular pressures. The use of anticholinergic drugs may precipitate angle closure with an increase in intraocular pressure. If blurring of vision occurs during therapy, the possibility of narrow angle glaucoma should be considered. Blindness has been reported due to aggravation of narrow angle glaucoma (see CONTRAINDICATIONS and ADVERSE REACTIONS)
ARTANE (trihexyphenidyl) should be administered with caution in hot weather, especially when given concomitantly with other atropine-like drugs to the chronically ill, alcoholics, those who have central nervous system disease, or those who do manual labor in a hot environment. Anhidrosis may occur more readily when some disturbance of sweating already exists. If there is evidence of anhidrosis, the possibility of hyperthermia should be considered. Dosage should be decreased so that the ability to maintain body heat equilibrium via perspiration is not impaired. Severe anhidrosis and fatal hyperthermia have occurred with the use of anticholinergics under the conditions described above.
Neuroleptic Malignant Syndrome
A potentially fatal symptom complex sometimes referred to as Neuroleptic Malignant Syndrome (NMS) has been reported in association with dose reduction or discontinuation of trihexyphenidyl. Clinical manifestations of NMS are hyperpyrexia, muscle rigidity, altered mental status and evidence of autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis and cardiac dysrhythmias).
The diagnostic evaluation of patients with this syndrome is complicated. In arriving at a diagnosis, it is important to identify cases where the clinical presentation includes both serious medical illness (eg, pneumonia, systemic infection, etc.) and untreated or inadequately treated extrapyramidal signs and symptoms (EPS). Other important considerations in the differential diagnosis include central anticholinergic toxicity, heat stroke, drug fever, and primary central nervous system (CNS) pathology.
Patients with cardiac, liver, or kidney disorders, or with hypertension, should be closely monitored.
Since ARTANE (trihexyphenidyl) has atropine-like properties, patients on long-term treatment should be carefully monitored for untoward reactions.
Since ARTANE (trihexyphenidyl) has parasympatholytic activity, it should be used with caution in patients with glaucoma, obstructive disease of the gastrointestinal or genitourinary tracts, and in elderly males with possible prostatic hypertrophy. Incipient glaucoma may be precipitated by parasympatholytic drugs such as ARTANE (trihexyphenidyl) .
Tardive dyskinesia may appear in some patients on long-term therapy with antipsychotic drugs or may occur after therapy with these drugs has been discontinued. Antiparkinsonism agents do not alleviate the symptoms of tardive dyskinesia, and in some instances may aggravate them. However, parkinsonism and tardive dyskinesia often coexist in patients receiving chronic neuroleptic treatment, and anticholinergic therapy with ARTANE (trihexyphenidyl) may relieve some of these parkinsonism symptoms. ARTANE (trihexyphenidyl) is not recommended for use in patients with tardive dyskinesia unless they have concomitant Parkinson's disease.
Patients with arteriosclerosis or with a history of idiosyncrasy to other drugs may exhibit reactions of mental confusion, agitation, disturbed behavior, or nausea and vomiting. Such patients should be allowed to develop a tolerance through the initial administration of a small dose and gradual increase in dose until an effective level is reached. If a severe reaction should occur, administration of the drug should be discontinued for a few days and then resumed at a lower dosage. Psychiatric disturbances can result from indiscriminate use (leading to overdosage) to sustain continued euphoria. (See Drug Abuse And Dependence)
Abrupt withdrawal of treatment for parkinsonism may result in acute exacerbation of parkinsonism symptoms; therefore, abrupt withdrawal should be avoided (see DOSAGE AND ADMINISTRATION)
It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when ARTANE (trihexyphenidyl) is administered to a nursing woman. As with other anticholinergics, trihexyphenidyl may cause suppression of lactation. Therefore, trihexyphenidyl should only be used if the expected benefit to the mother outweighs the potential risk to the infant.
Safety and effectiveness in pediatric patients have not been established. (See also ADVERSE REACTIONS.)This monograph has been modified to include the generic and brand name in many instances.
Last reviewed on RxList: 3/16/2009
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