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Generic Name: pyridostigmine (py rid o STIG meen)
Brand Name: Mestinon, Mestinon Timespan, Regonol

What is pyridostigmine?

Pyridostigmine affects chemicals in the body that are involved in the communication between nerve impulses and muscle movement.

Pyridostigmine is used to treat the symptoms of myasthenia gravis. It is also used in military personnel who have been exposed to nerve gas.

Pyridostigmine may also be used for purposes not listed in this medication guide.

What is the most important information I should know about pyridostigmine?

You should not use pyridostigmine if you you have a bladder or bowel obstruction.

What should I discuss with my health care provider before taking pyridostigmine?

You should not use pyridostigmine if you are allergic to it, or if you have a bladder or bowel obstruction.

To make sure you can safely take pyridostigmine, tell your doctor if you have any of these other conditions:

  • asthma; or

  • kidney disease.

FDA pregnancy category C. It is not known whether pyridostigmine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medicine.

It is not known whether pyridostigmine passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Pyridostigmine is not approved for use by anyone younger than 18 years old.

How should I take pyridostigmine?

Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Take this medicine with food or milk if it upsets your stomach.

Do not crush, chew, or break an extended-release tablet. Swallow it whole.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

The amount and timing of this medicine is extremely important to the success of your treatment. Carefully follow your doctor's instructions about how much medicine to take and when to take it.

Your doctor may occasionally change your dose to make sure you get the best results. You may be asked to keep a daily record of when you took each dose and how long the effects lasted. This will help your doctor determine if your dose needs to be adjusted.

If you need surgery, tell the surgeon ahead of time that you are using pyridostigmine. You may need to stop using the medicine for a short time.

Store at room temperature away from moisture and heat.

Keep the tablets in their original container, along with the canister of moisture-absorbing preservative that comes with this medicine.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include nausea, vomiting, diarrhea, stomach cramps, sweating, blurred vision, drooling, and weak or shallow breathing.

Worsening muscle weakness, or no change in your myasthenia gravis symptoms, may also be signs of overdose.

What should I avoid while taking pyridostigmine?

This medication may cause blurred vision or impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert and able to see clearly.

Drinking alcohol can increase certain side effects of pyridostigmine.

Pyridostigmine side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using pyridostigmine and call your doctor at once if you have any of these serious side effects:

  • extreme muscle weakness;

  • loss of movement in any part of your body;

  • weak or shallow breathing;

  • slurred speech, vision problems; or

  • worsening or no improvement in your symptoms of myasthenia gravis.

Common side effects may include:

  • stomach pain, nausea, vomiting, diarrhea;

  • muscle cramps, twitching;

  • sweating, increased salivation;

  • cough with mucus;

  • rash; or

  • blurred vision.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Side effects (in more detail)

Pyridostigmine dosing information

Usual Adult Dose for Nerve Agent Pretreatment:

Soman pretreatment:
30 mg orally every 8 hours starting at least 8 hours before anticipated nerve gas exposure.

Pyridostigmine is not effective and should not be taken at the time of, or after exposure to, nerve agents. Immediate treatment with parenteral atropine and pralidoxime is required if nerve agent exposure occurs.

Pretreatment has been used for up to 14 to 21 days.

Pyridostigmine has also been used as nerve agent pretreatment (NAPP) against other substances. In animal studies, pretreatment, together with atropine and pralidoxime postexposure treatment, was effective in increasing survival after tabun and soman poisoning, variably effective against cyclosarin, and ineffective against sarin and VX.

Usual Adult Dose for Reversal of Nondepolarizing Muscle Relaxants:

10 to 20 mg by slow IV injection.
Atropine sulfate 0.6 to 1.2 mg IV is recommended immediately before pyridostigmine injection.

Airway and ventilation should be maintained until recovery of normal respiration.

Usual Adult Dose for Myasthenia Gravis:

Immediate-release tablets and syrup:
Initial dose: 60 mg orally 3 times daily.
Maintenance dose: Increase dose as needed in intervals of at least 48 hours. Results of dose adjustments may take several days to become apparent. Effective doses have range from 60 mg to 1500 mg per day in 3 to 6 divided doses.

Sustained-release tablets: 180 to 540 mg orally once or twice daily, not more often than 6-hour intervals. May be used with immediate-release tablets or syrup to provide accurate dose titration and optimal control of symptoms.

2 to 5 mg IM or slow IV every 2 to 3 hours. To supplement oral dosage pre- and postoperatively, during labor and postpartum, during myasthenic crisis (differentiate between cholinergic and myasthenic crisis before administering), or when oral therapy is not possible, one-thirtieth of the oral dose (i.e., 2 mg IV for every 60 mg oral) may be given.

The use of continuous IV infusions at rates of 2 to 4 mg/hour has been reported in the management of myasthenic crisis.

Usual Pediatric Dose for Reversal of Nondepolarizing Muscle Relaxants:

Children: 0.1 to 0.25 mg/kg/dose IV preceded by atropine or glycopyrrolate

Airway and ventilation should be maintained until recovery of normal respiration.

Usual Pediatric Dose for Myasthenia Gravis:

Myasthenia gravis: Dosage should be adjusted such that larger doses administered prior to time of greatest fatigue.

Neonatal: (A benzyl alcohol-free formulation should be used for neonates):
Oral: 5 mg every 4 to 6 hours
IM, IV: 0.05 to 0.15 mg/kg/dose

Oral: 7 mg/kg/day in 5 to 6 divided doses
IM, IV: 0.05 to 0.15 mg/kg/dose (maximum single dose: 10 mg)

What other drugs will affect pyridostigmine?

Other drugs may interact with pyridostigmine, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Where can I get more information?

  • Your pharmacist can provide more information about pyridostigmine.
  • Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
  • Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2012 Cerner Multum, Inc. Version: 3.01.

Date modified: November 15, 2017
Last reviewed: November 19, 2014