Antimyasthenic (oral route, parenteral route)

Brand Name

US Brand Name

Aricept

Exelon

Mestinon

Mestinon Timespan

Prostigmin Bromide

Razadyne

Razadyne ER

Razadyne IR

Zunveyl

Canadian Brand Name

Reminyl

Description

Antimyasthenics are given by mouth or by injection to treat myasthenia gravis. Neostigmine may also be given by injection as a test for myasthenia gravis. Sometimes neostigmine is given by injection to prevent or treat certain urinary tract or intestinal disorders. In addition, neostigmine or pyridostigmine may be given by injection as an antidote to certain types of muscle relaxants used in surgery.

These medicines are available only with your doctor's prescription.

This product is available in the following dosage forms:

Tablet, Extended Release
Solution
Tablet
Capsule, Extended Release
Capsule
Tablet, Disintegrating

Before Using

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to medicines in this group 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

Although there is no specific information comparing use of antimyasthenics in children with use in other age groups, these medicines are not expected to cause different side effects or problems in children than they do in adults.

Geriatric

Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults. Although there is not much information comparing use of antimyasthenics in the elderly with use in other age groups, these medicines are not expected to cause different side effects or problems in older people than they do in younger adults.

Pregnancy

Antimyasthenics have not been reported to cause birth defects; however, muscle weakness has occurred temporarily in some newborn babies whose mothers took antimyasthenics during pregnancy.

Breastfeeding

Antimyasthenics have not been reported to cause problems in nursing babies.

Drug Interactions

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 taking any of these medicines, 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 medicines in this class with any of the following medicines is not recommended. Your doctor may decide not to treat you with a medication in this class or change some of the other medicines you take.

Atropine
Bepridil
Bromopride
Cisapride
Dronedarone
Fluconazole
Ketoconazole
Levoketoconazole
Mesoridazine
Pimozide
Piperaquine
Posaconazole
Saquinavir
Sparfloxacin
Terfenadine
Thioridazine
Viloxazine
Ziprasidone

Using medicines in this class 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.

Abiraterone Acetate
Abiraterone Acetate, Micronized
Acebutolol
Acetophenazine
Aclidinium
Acrivastine
Adagrasib
Alcaftadine
Alfentanil
Alfuzosin
Amantadine
Ambenonium
Amdinocillin
Amifampridine
Amineptine
Aminophylline
Amiodarone
Amisulpride
Amitriptyline
Amitriptylinoxide
Amoxapine
Amphetamine
Ampicillin
Anagrelide
Anisotropine
Antazoline
Apomorphine
Aripiprazole
Aripiprazole Lauroxil
Arsenic Trioxide
Asenapine
Astemizole
Atazanavir
Atenolol
Atomoxetine
Atropine
Azatadine
Azelastine
Azithromycin
Azlocillin

Other Interactions

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. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using medicines in this class with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use your medicine, or give you special instructions about the use of food, alcohol, or tobacco.

Bitter Orange
Grapefruit Juice
Tobacco

Proper Use

Your doctor may want you to take this medicine with food or milk to help lessen the chance of side effects. If you have any questions about how you should be taking this medicine, check with your doctor.

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

If you are taking this medicine for myasthenia gravis:

When you first begin taking this medicine, your doctor may want you to keep a daily record of:
- the time you take each dose.
- how long you feel better after taking each dose.
- how long you feel worse.
- any side effects that occur.

This is to help your doctor decide whether the dose of this medicine should be increased or decreased and how often the medicine should be taken in order for it to be most effective in your condition.

Dosing

The dose medicines in this class 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 these medicines. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine 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 using the medicine.

For ambenonium

For oral dosage form (tablets):
- For myasthenia gravis:
  - Adults and teenagers—At first, the dose is 5 milligrams (mg) three or four times per day. Then, if needed, the dose will be adjusted by your doctor.
  - Children—The dose is based on body weight or size and must be determined by your doctor. The total daily dose is usually 300 micrograms (mcg) per kilogram (kg) (136 mcg per pound) of body weight or 10 mg per square meter of body surface area. This dose may be divided into three or four smaller doses. If needed, the total daily dose will be increased to 1.5 mg per kg (0.68 mg per pound) of body weight or 50 mg per square meter of body surface area. This dose may be divided into three or four smaller doses.

For neostigmine

For oral dosage form (tablets):
- For myasthenia gravis:
  - Adults and teenagers—At first, the dose is 15 milligrams (mg) every three or four hours. Then, the dose is 150 mg taken over a twenty-four-hour period.
  - Children—The dose is based on body weight or size and must be determined by your doctor. The total daily dose is usually 2 mg per kilogram (kg) (0.91 mg per pound) of body weight or 60 mg per square meter of body surface area. This dose may be divided into six to eight smaller doses.
For injection dosage form:
- For myasthenia gravis:
  - Adults and teenagers—The usual dose is 500 micrograms (mcg) injected into a muscle or under the skin.
  - Children—The dose is based on body weight and must be determined by your doctor. It is usually 10 to 40 mcg per kg (4.5 to 18.2 mcg per pound) of body weight, injected into a muscle or under the skin, every two or three hours.
- For urinary tract or intestinal disorders:
  - Adults and teenagers—The usual dose is 250 to 500 mcg, injected into a muscle or under the skin, as needed.
  - Children—Use and dose must be determined by your doctor.

For pyridostigmine

For oral dosage forms (syrup and tablets):
- For myasthenia gravis:
  - Adults and teenagers—At first, the dose is 30 to 60 milligrams (mg) every three or four hours. Then, the dose is 60 mg to 1.5 grams (usually 600 mg) per day.
  - Children—The dose is based on body weight or size and must be determined by your doctor. The total daily dose is usually 7 mg per kilogram (kg) (3.2 mg per pound) of body weight or 200 mg per square meter of body surface area. This dose may be divided into five or six smaller doses.
For long-acting oral dosage form (extended-release tablets):
- For myasthenia gravis:
  - Adults and teenagers—The usual dose is 180 to 540 mg one or two times per day.
  - Children—Dose must be determined by your doctor.
For injection dosage form:
- For myasthenia gravis:
  - Adults and teenagers—The usual dose is 2 mg, injected into a muscle or vein, every two or three hours.
  - Children—The dose is based on body weight and must be determined by your doctor. It is usually 50 to 150 micrograms (mcg) per kg (22.7 to 68.1 mcg per pound) of body weight, injected into a muscle every four to six hours.

Missed Dose

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

Storage

Keep out of the reach of children.

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Do not keep outdated medicine or medicine no longer needed.

Keep the syrup form of pyridostigmine from freezing.

Side Effects

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 immediately if any of the following side effects occur:

Symptoms of overdose

Blurred vision
clumsiness or unsteadiness
confusion
convulsions (seizures)
diarrhea (severe)
increase in bronchial secretions or watering of mouth (excessive)
increasing muscle weakness (especially in the arms, neck, shoulders, and tongue)
muscle cramps or twitching
nausea or vomiting (severe)
shortness of breath, troubled breathing, wheezing, or tightness in chest
slow heartbeat
slurred speech
stomach cramps or pain (severe)
unusual irritability, nervousness, restlessness, or fear
unusual tiredness or weakness

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

Rare

Redness, swelling, or pain at place of injection (for pyridostigmine injection only)
skin rash (does not apply to ambenonium)

Some 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. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Diarrhea
increased sweating
increased watering of mouth
nausea or vomiting
stomach cramps or pain

Less common

Frequent urge to urinate
increase in bronchial secretions
unusually small pupils
unusual watering of eyes

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

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

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