Benztropine Injection

In the U.S.

• Cogentin

Available Dosage Forms:

• Solution

Therapeutic Class: Antiparkinsonian

Pharmacologic Class: Anticholinergic

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For benztropine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to benztropine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Because of benztropine's toxicity, it should be used with caution in children 3 years of age or older. It is not recommended for use in children below 3 years of age.

Geriatric

No information is available on the relationship of age to the effects of benztropine injection in geriatric patients.

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving benztropine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using benztropine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

• Potassium

Using benztropine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Tiotropium

Using benztropine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

• Betel Nut
• Chlorpromazine
• Haloperidol

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of benztropine. Make sure you tell your doctor if you have any other medical problems, especially:

• Enlarged prostate or
• Glaucoma or
• Paralytic ileus (bowel blockage), history of or
• Psychosis (mental disorder) or
• Tachycardia (fast heartbeat) or
• Urinating problems (e.g., painful or difficult urination, urinary retention)—Use with caution. May make these conditions worse.

• Glaucoma, angle-closure or
• Tardive dyskinesia (movement disorder)—Should not be used in patients with these conditions.

For all patients taking benztropine injection:

• If you have an allergy to benztropine or any other part of this medicine.
• If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
• If you have a very bad muscle problem called tardive dyskinesia.
• If you have glaucoma.

Children:

• If your child is younger than 3 years of age. Do not give to a child younger than 3 years of age.

This is not a list of all drugs or health problems that interact with benztropine injection.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this medicine with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

Benztropine mesylate possesses both anticholinergic and antihistaminic effects, although only the former have been established as therapeutically significant in the management of parkinsonism. 

In the isolated guinea pig ileum, the anticholinergic activity of this drug is about equal to that of atropine; however, when administered orally to unanesthetized cats, it is only about half as active as atropine.

In laboratory animals, its antihistaminic activity and duration of action approach those of pyrilamine maleate.

Since there is no significant difference in onset of effect after intravenous or intramuscular injection, usually there is no need to use the intravenous route. The drug is quickly effective after either route, with improvement sometimes noticeable a few minutes after injection.  In emergency situations, when the condition of the patient is alarming, 1 to 2 mL of the injection normally will provide quick relief.  If the parkinsonian effect begins to return, the dose can be repeated.

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 parenterally.

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 when given 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 SINEMET® (Carbidopa-Levodopa), or with levodopa, in which case 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 parenterally.  Dosage must be individualized according to the need of the patient.  Some patients require more than recommended; others do not need as much.

In acute dystonic reactions, 1 to 2 mL of the injection usually relieves the condition quickly.

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 two or three times a day usually provides relief within one or two days.  If such disorders recur, benztropine mesylate can be reinstituted.

Certain drug-induced extrapyramidal disorders that develop slowly may not respond to benztropine mesylate.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration.

Consult your pharmacist.

Keep a list of all your medications with you, and share the list with your doctor and pharmacist.