BENZTROPINE: 2,228 Adverse Event Reports & Safety Profile

DESCRIPTION Benztropine Mesylate, USP is a synthetic compound containing structural features found in atropine and diphenhydramine. It is designated chemically as 8-azabicyclo[3.2.1] octane, 3-(diphenylmethoxy)-, endo, methanesulfonate. Its empirical formula is C 21 H 25 NO•CH 4 O 3 S, and its structural formula is: Benztropine mesylate is a crystalline white powder, very soluble in water, and has a molecular weight of 403.54.

Benztropine Mesylate

Injection, USP is supplied as a sterile injection for intravenous and intramuscular use. Each milliliter of the injection contains: Benztropine Mesylate, USP: .............................................................................................1 mg Sodium Chloride, USP: .....................................................................................................9 mg Water for Injection q.s: ......................................................................................................1 mL Benztropine mesylate structural formula

INDICATIONS AND USAGE Benztropine mesylate tablets, USP are indicated for use as an adjunct in the therapy of all forms of parkinsonism. Useful also in the control of extrapyramidal disorders (except tardive dyskinesia - see PRECAUTIONS ) due to neuroleptic drugs (e.g., phenothiazines).

DOSAGE AND ADMINISTRATION Benztropine mesylate tablets should be used when patients are able to take oral medication. Because of cumulative action, therapy should be initiated with a low dose which is increased gradually at five- or six-day intervals to the smallest amount necessary for optimal relief. Increases should be made in increments of 0.5 mg, to a maximum of 6 mg, or until optimal results are obtained without excessive adverse reactions. Postencephalitic and Idiopathic Parkinsonism The usual daily dose is 1 to 2 mg with a range of 0.5 to 6 mg orally. As with any agent used in parkinsonism, dosage must be individualized according to age and weight, and the type of parkinsonism being treated. Generally, older patients, and thin patients cannot tolerate large doses. Most patients with postencephalitic parkinsonism need fairly large doses and tolerate them well. Patients with a poor mental outlook are usually poor candidates for therapy. In idiopathic parkinsonism, therapy may be initiated with a single daily dose of 0.5 to 1 mg at bedtime. In some patients, this will be adequate; in others 4 to 6 mg a day may be required. In postencephalitic parkinsonism, therapy may be initiated in most patients with 2 mg a day in one or more doses. In highly sensitive patients, therapy may be initiated with 0.5 mg at bedtime, and increased as necessary. Some patients experience greatest relief by taking the entire dose at bedtime; others react more favorably to divided doses, two to four times a day. Frequently, one dose a day is sufficient, and divided doses may be unnecessary or undesirable. The long duration of action of this drug makes it particularly suitable for bedtime medication when its effects may last throughout the night, enabling patients to turn in bed during the night more easily, and to rise in the morning. When benztropine mesylate is started, do not terminate therapy with other antiparkinsonian agents abruptly. If the other agents are to be reduced or discontinued, it must be done gradually. Many patients obtain greatest relief with combination therapy. Benztropine mesylate may be used concomitantly with carbidopa-levodopa, or with levodopa, in which case periodic dosage adjustment may be required in order to maintain optimum response. Drug-Induced Extrapyramidal Disorders In treating extrapyramidal disorders due to neuroleptic drugs (e.g., phenothiazines), the recommended dosage is 1 to 4 mg once or twice a day orally. Dosage must be individualized according to the need of the patient. Some patients require more than recommended; others do not need as much. When extrapyramidal disorders develop soon after initiation of treatment with neuroleptic drugs (e.g., phenothiazines), they are likely to be transient. One to 2 mg of benztropine mesylate tablets two or three times a day usually provides relief within one or two days. After one or two weeks the drug should be withdrawn to determine the continued need for it. If such disorders recur, benztropine mesylate can be reinstituted. Certain drug-induced extrapyramidal disorders that develop slowly may not respond to benztropine mesylate.

Postencephalitic and Idiopathic Parkinsonism The usual daily dose is 1 to 2 mg with a range of 0.5 to 6 mg orally. As with any agent used in parkinsonism, dosage must be individualized according to age and weight, and the type of parkinsonism being treated. Generally, older patients, and thin patients cannot tolerate large doses. Most patients with postencephalitic parkinsonism need fairly large doses and tolerate them well. Patients with a poor mental outlook are usually poor candidates for therapy. In idiopathic parkinsonism, therapy may be initiated with a single daily dose of 0.5 to 1 mg at bedtime. In some patients, this will be adequate; in others 4 to 6 mg a day may be required. In postencephalitic parkinsonism, therapy may be initiated in most patients with 2 mg a day in one or more doses. In highly sensitive patients, therapy may be initiated with 0.5 mg at bedtime, and increased as necessary. Some patients experience greatest relief by taking the entire dose at bedtime; others react more favorably to divided doses, two to four times a day. Frequently, one dose a day is sufficient, and divided doses may be unnecessary or undesirable. The long duration of action of this drug makes it particularly suitable for bedtime medication when its effects may last throughout the night, enabling patients to turn in bed during the night more easily, and to rise in the morning. When benztropine mesylate is started, do not terminate therapy with other antiparkinsonian agents abruptly. If the other agents are to be reduced or discontinued, it must be done gradually. Many patients obtain greatest relief with combination therapy. Benztropine mesylate may be used concomitantly with carbidopa-levodopa, or with levodopa, in which case periodic dosage adjustment may be required in order to maintain optimum response.

Drug-Induced Extrapyramidal Disorders In treating extrapyramidal disorders due to neuroleptic drugs (e.g., phenothiazines), the recommended dosage is 1 to 4 mg once or twice a day orally. Dosage must be individualized according to the need of the patient. Some patients require more than recommended; others do not need as much. When extrapyramidal disorders develop soon after initiation of treatment with neuroleptic drugs (e.g., phenothiazines), they are likely to be transient. One to 2 mg of benztropine mesylate tablets two or three times a day usually provides relief within one or two days. After one or two weeks the drug should be withdrawn to determine the continued need for it. If such disorders recur, benztropine mesylate can be reinstituted. Certain drug-induced extrapyramidal disorders that develop slowly may not respond to benztropine mesylate.

CONTRAINDICATIONS Hypersensitivity to benztropine mesylate tablets or to any component of the tablets. Because of its atropine-like side effects, this drug is contraindicated in pediatric patients under three years of age, and should be used with caution in older pediatric patients.

ADVERSE REACTIONS: The adverse reactions below, most of which are anticholinergic in nature, have been reported and within each category are listed in order of decreasing severity.

Cardiovascular

Tachycardia.

Digestive

Paralytic ileus, constipation, vomiting, nausea, dry mouth. If dry mouth is so severe that there is difficulty in swallowing or speaking, or loss of appetite and weight, reduce dosage, or discontinue the drug temporarily. Slight reduction in dosage may control nausea and still give sufficient relief of symptoms. Vomiting may be controlled by temporary discontinuation, followed by resumption at a lower dosage.

Nervous System

Toxic psychosis, including confusion, disorientation, memory impairment, visual hallucinations; exacerbation of pre-existing psychotic symptoms; nervousness; depression; listlessness; numbness of fingers.

Special Senses

Blurred vision, dilated pupils.

Urogenital

Urinary retention, dysuria. Metabolic/Immune or Skin Occasionally, an allergic reaction, e.g., skin rash, develops. If this cannot be controlled by dosage reduction, the medication should be discontinued.

Other

Heat stroke, hyperthermia, fever. To report SUSPECTED ADVERSE REACTIONS, contact Fresenius Kabi, Vigilance & Medical Affairs at 1-800-551-7176 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .

WARNINGS Safe use in pregnancy has not been established. Benztropine mesylate injection, USP may impair mental and/or physical abilities required for performance of hazardous tasks, such as operating machinery or driving a motor vehicle.

When

Benztropine mesylate injection, USP is given concomitantly with phenothiazines, haloperidol, or other drugs with anticholinergic or antidopaminergic activity, patients should be advised to report gastrointestinal complaints, fever or heat intolerance promptly. Paralytic ileus, hyperthermia and heat stroke, all of which have sometimes been fatal, have occurred in patients taking anticholinergic-type antiparkinsonism drugs, including Benztropine mesylate injection, USP in combination with phenothiazines and/or tricyclic antidepressants.

Since

Benztropine mesylate injection, USP contains structural features of atropine, it may produce anhidrosis. For this reason, it should be administered with caution during hot weather, especially when given concomitantly with other atropine-like drugs to the chronically ill, the alcoholic, those who have central nervous system disease, and 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 at the discretion of the physician so that the ability to maintain body heat equilibrium by perspiration is not impaired. Severe anhidrosis and fatal hyperthermia have occurred.

PRECAUTIONS General: Since Benztropine mesylate injection, USP has cumulative action, continued supervision is advisable. Patients with a tendency to tachycardia and patients with prostatic hypertrophy should be observed closely during treatment. Dysuria may occur, but rarely becomes a problem. Urinary retention has been reported with Benztropine mesylate injection, USP. The drug may cause complaints of weakness and inability to move particular muscle groups, especially in large doses. For example, if the neck has been rigid and suddenly relaxes, it may feel weak, causing some concern. In this event, dosage adjustment is required. Mental confusion and excitement may occur with large doses, or in susceptible patients. Visual hallucinations have been reported occasionally. Furthermore, in the treatment of extrapyramidal disorders due to neuroleptic drugs (e.g., phenothiazines), in patients with mental disorders, occasionally there may be intensification of mental symptoms. In such cases, antiparkinsonian drugs can precipitate a toxic psychosis. Patients with mental disorders should be kept under careful observation, especially at the beginning of treatment or if dosage is increased. Tardive dyskinesia may appear in some patients on long-term therapy with phenothiazines and related agents, or may occur after therapy with these drugs have been discontinued. Antiparkinsonism agents do not alleviate the symptoms of tardive dyskinesia, and in some instances may aggravate them. Benztropine mesylate injection, USP is not recommended for use in patients with tardive dyskinesia. The physician should be aware of the possible occurrence of glaucoma. Although the drug does not appear to have any adverse effect on simple glaucoma, it probably should not be used in angle-closure glaucoma.

Drug

Interactions: Antipsychotic drugs such as phenothiazines or haloperidol; tricyclic antidepressants (see WARNINGS ).

Pediatric

Use: Because of the atropine-like side effects, Benztropine mesylate injection, USP should be used with caution in pediatric patients over three years of age (see CONTRAINDICATIONS ).

Geriatric

Use: Clinical studies of Benztropine mesylate injection, USP did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should start at the low end of the dosing range (see DOSAGE AND ADMINISTRATION ) and the dose should be increased only as needed with monitoring for the emergence of adverse events (see PRECAUTIONS and ADVERSE REACTIONS ).

Drug Interactions Antipsychotic drugs such as phenothiazines or haloperidol; tricyclic antidepressants [ see WARNINGS ].