Pyridostigmine Bromide

What is pyridostigmine bromide?

Pyridostigmine bromide (brand names: Mestinon®, Distinon®, Gravitor®, Kalymin®, Regonol®) is a medication that affects the way nerves communicate with muscles and is used to treat myasthenia gravis.

Its use in dogs and occasionally cats to treat myasthenia gravis is off label (extra label). Many drugs are commonly prescribed for off-label use in veterinary medicine.

“Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.

How is pyridostigmine bromide given?

• Pyridostigmine bromide is given by mouth in the form of a tablet or liquid. It may also be given by injection in the hospital.
• Measure liquid forms carefully.
• Pyridostigmine bromide may be given with or without food, but be consistent (always dose with food, or always dose without food), as switching back and forth can change the amount of drug that gets into your pet’s bloodstream.
• If your pet vomits when dosed on an empty stomach, give future doses with food.

This medication will take effect quickly, in about 1 to 2 hours, and improvement in clinical signs should follow.

What if I miss giving my pet the medication?

If you miss a dose, give it as soon as you remember, and then wait the recommended time as prescribed by your veterinarian for the next dose. Do not give the pet two doses at once.

Are there any potential side effects?

Pyridostigmine bromide may cause the following side effects (usually related to the dose):

• Drooling
• Diarrhea
• Increased urination
• Abdominal pain
• Muscle cramps 
• Increased tear production

Serious adverse reactions may occur. If any of the following signs develop, stop giving pyridostigmine bromide and contact your veterinarian immediately:

• Severe vomiting
• Severe diarrhea
• Cough
• Difficulty breathing
• Vision problems
• Collapse
• Weakness
• Seizures
• Slow or racing heart rate
• Low blood pressure

Other side effects may occur. If you notice anything unusual, contact your veterinarian immediately. This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

DO NOT USE pyridostigmine bromide in pets that:

• Are allergic to it or other bromides
• Have urinary or gastrointestinal tract obstructions or blockages

USE WITH CAUTION in:

• Cats
• Pets with lung problems, such as asthma or bronchitis
• Pets with seizures
• Pets with kidney disease
• Pets with overactive thyroid gland
• Pets with abnormal heart rate/rhythm
• Pets with stomach/intestinal ulcers
• Pets that are pregnant or lactating

Are there any drug interactions I should be aware of?

Several medications should be used with caution when given with pyridostigmine bromide, including:

• Beta blockers
• Corticosteroids
• Drugs with neuromuscular blocking ability
• Magnesium

Certain medications may interact with pyridostigmine bromide, so be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.

Is any monitoring needed with this medication?

• At home, monitor for any side effects such as those noted above. If any occur, stop using the medication and contact your veterinarian. Side effects may indicate the dose is too high.
• Your veterinarian will let you know when and how they want to reassess your pet to ensure the medication is working and not causing side effects.

How do I store pyridostigmine bromide?

• Store at room temperature unless otherwise directed on the label.
• The liquid form should be protected from freezing and protected from light.
• Tablets should be protected from moisture and light.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet’s weight and symptoms.