Mestinon (pyridostigmine) is used for conditions such as myasthenia gravis and congenital myasthenic syndrome, to increase muscle strength. Mestinon works by preventing the breakdown of acetylcholine, which is a natural substance that the body needs for muscles to work well.  Mestinon may also be used to reverse the effect of non-depolarizing neuromuscular blocking medication and can be used in military personnel who have been exposed to nerve gas.

Mestinon is a cholinesterase inhibitor that works by reducing the breakdown of acetylcholine in the neuromuscular junction, this increases the signals between nerves and muscles and relieves symptoms of muscle weakness.

Clinical trials have used pyridostigmine to treat postural orthostatic tachycardia syndrome (POTS) but is not FDA approved for this condition.

Mestinon is available as Mestinon 60mg tablets, Mestinon Timespan 180mg (sustained release tablet) and Mestinon Oral Solution 60mg/5ml.  

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

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 (Mestinon Timespan). 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 Mestinon. You may need to stop using the medicine for a short time.

Mestinon is available as Mestinon 60mg tablets, Mestinon Timespan 180mg (sustained release tablet) and Mestinon Oral Solution 60mg/5ml.  

Usual Adult Dose of Mestinon for Myasthenia Gravis:

Immediate-release tablets and syrup: 

• 60 to 1500 mg daily (usually 600 mg/day divided into 5 or 6 doses) spaced to provide maximum relief.

Mestinon Timespan (Sustained-release tablet): 

• 180 mg to 540 mg once or twice daily (separated by at least 6 hours); it may be necessary to use the immediate-release tablets or oral solution in conjunction with the sustained-release tablets for optimum control.

Comments:

Not all products are approved for the same indications. Refer to the manufacturer product information for indications.

Usual Adult Dose of Mestinon for Reversal of Nondepolarizing Muscle Relaxants:

As a reversal agent or antagonist to the neuromuscular blocking effects of nondepolarizing muscle relaxants.

• The IV dose should be individualized. 
• The dosage information presented here is derived from studies based upon units of drug per unit of body weight and is intended to serve as a guide only:
  • When this drug is given IV to reverse the action of muscle relaxant drugs, it is recommended that atropine sulfate (0.6 to 1.2 mg) or an equipotent dose of glycopyrrolate be given immediately prior to or simultaneously with the administration of this drug to minimize excessive secretions and bradycardia.
  • Reversal doses range from 0.1 to 0.25 mg/kg.
  • The onset time to peak effect is dose-dependent; return of twitch height to 90% of control occurs within approximately 6 minutes following administration of a 0.25 mg/kg dose; at lower doses, full recovery usually occurs within 15 minutes in most patients, although others may require a half-hour or more.

Comments:

Not all products are approved for the same indications. Refer to the manufacturer product information for indications.

Satisfactory reversal can be evident by adequate voluntary respiration, respiratory measurements and use of a peripheral nerve stimulator device.

It is recommended that the patient be well ventilated and a patent airway maintained until complete recovery of normal respiration.

Dose Adjustments:

Renal dose adjustments: Lower doses may be required; however, no specific guidelines have been suggested. Caution recommended.

Liver Dose Adjustments: Data not available

You should not use Mestinon if: 

• you are allergic to it, or any of the inactive ingredients.
• if you have a bladder or bowel obstruction

Safety and effectiveness in pediatric patients have not been established.

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

• asthma; or
• kidney disease.

Pregnancy 

It is not known whether Mestinon will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using Mestinon. The use of this medicine in women who may become pregnant requires weighing the drug’s potential benefits against its possible hazards to mother and child.

Breastfeeding 

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.

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.

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.

This medicine may make you drowsy and may cause blurred vision. Do not drive a car or operate machinery until you know how this drug affects you.

Drinking alcohol can increase certain side effects of pyridostigmine including drowsiness.

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 Mestinon 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 of Mestinon 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.

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.

It is important to tell your doctor and pharmacist if you are taking:

• allergy or cold medications
• dexamethasone (Decadron)
• hydrocortisone (Hydrocortone)
• magnesium-containing products 
• medications for heart arrhythmias
• sleeping pills
• vitamins.

This is not a full list of interactions.  Click the link below to check for interactions.