Pyridostigmine Bromide

By Rania Gollakner, BS, DVM, MPH

What is pyridostigmine bromide?

Pyridostigmine bromide (brand names: Mestinon®, Distinon®, Gravitor®, Kalymin®, Regonol®) is an anticholinesterase agent used to treat myasthenia gravis.

Its use in dogs and occasionally cats to treat myasthenia gravis is ‘off label’ or ‘extra label’. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully as their directions 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 setting. It may be given with or without food, but be consistent, as switching back and forth can change the amount of drug that gets into your pet’s bloodstream (either always give with food or always give on an empty stomach). If your pet vomits when dosed on an empty stomach, give future doses with food. Measure liquid forms carefully.

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?

Give the missed dose as soon as you remember, and then wait the recommended amount of time between doses. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Side effects are usually related to the dose and may include drooling, diarrhea, increased urination, abdominal pain, muscle cramps, and increased tear production. Serious side effects include severe vomiting, severe diarrhea, cough, difficulty breathing, vision problems, collapse, weakness, seizures, slow or racing heart rate, and low blood pressure.

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, or in pets that have urinary or gastrointestinal tract obstructions or blockages. It should be used cautiously in pets with lung problems such as asthma or bronchitis, seizures, kidney disease, overactive thyroid gland, abnormal heart rate/rhythm, or stomach/intestinal ulcers. Pyridostigmine bromide should be used cautiously in pregnant or lactating pets. It should be used cautiously in cats.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with pyridostigmine bromide: atropine, beta blockers, corticosteroids, dexpanthenol, drugs with neuromuscular blocking ability, magnesium, surgical muscle relaxants, or quinidine.

Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

Monitor for serious side effects as these may indicate a dose that is too high. Your veterinarian may monitor your pet to be sure that the medication is working. Monitor your pet at home for 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. The 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.

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