Some commonly used brand names are:

In the U.S.—

In Canada—

Other commonly used names are: Benzatropine; Profenamine

• Antidyskinetic -- Benztropine; Biperiden; Ethopropazine; Procyclidine ; Trihexyphenidyl

Antidyskinetics are used to treat Parkinson's disease, sometimes referred to as ``shaking palsy.'' By improving muscle control and reducing stiffness, this medicine allows more normal movements of the body as the disease symptoms are reduced. It is also used to control severe reactions to certain medicines such as reserpine (e.g., Serpasil) (medicine to control high blood pressure) or phenothiazines, chlorprothixene (e.g., Taractan), thiothixene (e.g., Navane), loxapine (e.g., Loxitane), and haloperidol (e.g., Haldol) (medicines for nervous, mental, and emotional conditions).

Antidyskinetics may also be used for other conditions as determined by your doctor.

These medicines are available only with your doctor's prescription in the following dosage forms:

Oral
• Benztropine
  • Tablets (U.S. and Canada)
• Biperiden
  • Tablets (U.S. and Canada)
• Ethopropazine
  • Tablets (U.S. and Canada)
• Procyclidine
  • Elixir (Canada)
  • Tablets (U.S. and Canada)
• Trihexyphenidyl
  • Extended-release capsules (U.S. and Canada)
  • Elixir (U.S. and Canada)
  • Tablets (U.S. and Canada)

Parenteral
• Benztropine
  • Injection (U.S. and Canada)
• Biperiden
  • Injection (U.S.)

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 antidyskinetics, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to antidyskinetics. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Studies on effects in pregnancy have not been done in either humans or animals. However, antidyskinetics have not been shown to cause problems in humans.

Breast-feeding—It is not known if antidyskinetics pass into breast milk. Although most medicines pass into breast milk in small amounts, many of them may be used safely while breast-feeding. Mothers who are taking these medicines and who wish to breast-feed should discuss this with their doctor.

Since antidyskinetics tend to decrease the secretions of the body, it is possible that the flow of breast milk may be reduced in some patients.

Children—Children may be especially sensitive to the effects of antidyskinetics. This may increase the chance of side effects during treatment.

Older adults—Agitation, confusion, disorientation, hallucinations, memory loss, and mental changes are more likely to occur in elderly patients, who are usually more sensitive to the effects of antidyskinetics.

Other medicines—Although certain medicines should not be used together at all, in other cases 2 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 taking an antidyskinetic, it is especially important that your health care professional know if you are taking any of the following:

• Anticholinergics (medicine for abdominal or stomach spasms or cramps) or
• Central nervous system (CNS) depressants (medicine that causes drowsiness) or
• Tricyclic antidepressants (medicine for depression)—Using these medicines together with antidyskinetics may result in additive effects, increasing the chance of unwanted effects

• Difficult urination or
• Enlarged prostate or
• Glaucoma or
• Heart or blood vessel disease or
• High blood pressure or
• Intestinal blockage or
• Myasthenia gravis or
• Uncontrolled movements of hands, mouth, or tongue—Antidyskinetics may make the condition worse

• Kidney disease or
• Liver disease—Higher blood levels of the antidyskinetics may result, increasing the chance of side effects

Take this medicine only as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer period of time than your doctor ordered. To do so may increase the chance of side effects.

To lessen stomach upset, take this medicine with meals or immediately after meals, unless otherwise directed by your doctor.

Dosing—

The dose of antidyskinetics will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of benztropine, biperiden, ethopropazine, procyclidine, and trihexyphenidyl. If your dose is different, do not change it unless your doctor tells you to do so.

The number of capsules, tablets, or teaspoonfuls of elixir that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking antidyskinetics.

For benztropine
• For oral dosage forms (tablets):
  • For Parkinson's disease or certain severe side effects caused by some other medicines:
    • Adults—To start, 0.5 to 4 milligrams (mg) a day, depending on your condition. Your doctor will adjust your dose as needed; however, the dose is usually not more than 6 mg a day.
    • Children—Use and dose must be determined by your doctor.
• For injection dosage form:
  • For Parkinson's disease or certain severe side effects caused by some other medicines:
    • Adults—1 to 4 mg a day, depending on your condition. Your doctor will adjust your dose as needed; however, the dose is usually not more than 6 mg a day.
    • Children—Use and dose must be determined by your doctor.

For biperiden
• For oral dosage forms (tablets):
  • For Parkinson's disease or certain severe side effects caused by some other medicines:
    • Adults—2 mg up to four times a day. Your doctor will adjust your dose, depending on your condition; however, the dose is usually not more than 16 mg a day.
    • Children—Use and dose must be determined by your doctor.
• For injection dosage form:
  • For Parkinson's disease or certain severe side effects caused by some other medicines:
    • Adults—2 mg, injected into a muscle or vein. The dose may be repeated if needed; however, the dose is usually not given more than four times a day.
    • Children—Use and dose is based on body weight and must be determined by your doctor.

For ethopropazine
• For oral dosage forms (tablets):
  • For Parkinson's disease or certain severe side effects caused by some other medicines:
    • Adults—50 mg one or two times a day. Your doctor will adjust your dose as needed; however, the dose is usually not more than 600 mg a day.
    • Children—Use and dose must be determined by your doctor.

For procyclidine
• For oral dosage forms (elixir or tablets):
  • For Parkinson's disease or certain severe side effects caused by some other medicines:
    • Adults—To start, 2.5 mg three times a day after meals. Your doctor may need to adjust your dose, depending on your condition.
    • Children—Use and dose must be determined by your doctor.

For trihexyphenidyl
• For extended-release oral dosage forms (extended-release capsules):
  • For Parkinson's disease or certain severe side effects caused by some other medicines:
    • Adults—5 mg after breakfast. Your doctor may add another 5 mg dose to be taken twelve hours later, depending on your condition.
    • Children: Use and dose must be determined by your doctor.
• For other oral dosage forms (elixir or tablets):
  • For Parkinson's disease or certain severe side effects caused by some other medicines:
    • Adults—To start, 1 to 2 mg a day. Your doctor may adjust your dose as needed; however, the dose is usually not more than 15 mg a day.
    • Children—Use and dose must be determined by your doctor.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is within 2 hours of your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store the capsule or tablet form of this medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Keep the liquid form of this medicine from freezing.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Your doctor should check your progress at regular visits, especially for the first few months you take this medicine. This will allow your dosage to be changed as necessary to meet your needs.

Your doctor may want you to have your eyes examined by an ophthalmologist (eye doctor) before and also sometime later during treatment.

Do not stop taking this medicine without first checking with your doctor. Your doctor may want you to reduce gradually the amount you are taking before stopping completely, to prevent side effects or the worsening of your condition.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using this medicine.

Do not take this medicine within 1 hour of taking medicine for diarrhea. Taking these medicines too close together will make this medicine less effective.

If you think you or anyone else has taken an overdose of this medicine, get emergency help at once. Taking an overdose of this medicine may lead to unconsciousness. Some signs of an overdose are clumsiness or unsteadiness; seizures; severe drowsiness; severe dryness of mouth, nose and throat; fast heartbeat; hallucinations (seeing, hearing, or feeling things that are not there); mood or mental changes; shortness of breath or troubled breathing; trouble in sleeping; and unusual warmth, dryness, and flushing of skin.

This medicine may cause your eyes to become more sensitive to light than they are normally. Wearing sunglasses and avoiding too much exposure to bright light may help lessen the discomfort.

This medicine may cause some people to have blurred vision or to become drowsy, dizzy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert or able to see well.

Dizziness, lightheadedness, or fainting may occur, especially when you get up from lying or sitting. Getting up slowly may help. If the problem continues or gets worse, check with your doctor.

This medicine may make you sweat less, causing your body temperature to increase. Use extra care to avoid becoming overheated during exercise or hot weather while you are taking this medicine, since overheating may result in heat stroke. Also, hot baths or saunas may make you feel dizzy or faint while you are taking this medicine.

This medicine may cause dryness of the mouth. For temporary relief, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• Rare
  • Confusion (more common in the elderly or with high doses);  eye pain;  skin rash 
  
  

• Symptoms of overdose
  • Clumsiness or unsteadiness;  drowsiness (severe);  dryness of mouth, nose, or throat (severe) ;  fast heartbeat;  hallucinations (seeing, hearing, or feeling things that are not there);  mood or mental changes;  seizures;  shortness of breath or troubled breathing;  trouble in sleeping;  warmth, dryness, and flushing of skin  
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Blurred vision;  constipation;  decreased sweating;  difficult or painful urination (especially in older men);  drowsiness;  dryness of mouth, nose, or throat;  increased sensitivity of eyes to light;  nausea or vomiting 
  
  

• Less common or rare
  • Dizziness or lightheadedness when getting up from a lying or sitting position;  false sense of well-being (especially in the elderly or with high doses);  headache;  loss of memory (especially in the elderly);  muscle cramps;  nervousness;  numbness or weakness in hands or feet;  soreness of mouth and tongue;  stomach upset or pain;  unusual excitement (more common with large doses of trihexyphenidyl)  
  
  

After you stop using this medicine, your body may need time to adjust. The length of time this takes depends on the amount of medicine you were using and how long you used it. During this period of time check with your doctor if you notice any of the following side effects:

• Anxiety;  difficulty in speaking or swallowing ;  dizziness or lightheadedness when getting up from a lying or sitting position;  fast heartbeat;  loss of balance control;  mask-like face ;  muscle spasms, especially of face, neck, and back ;  restlessness or desire to keep moving;  shuffling walk;  stiffness of arms or legs;  trembling and shaking of hands and fingers ;  trouble in sleeping;  twisting movements of body 

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.