Amantadine

By Rania Gollakner, BS, DVM

Medications

What is amantadine?

Amantadine (brand names: Symmetrel®, Gocovri®, Osmolex ER®, Endantadine®) is an antiviral medication that also has some pain control effects. Its use in small animals is primarily for the treatment of pain, and it is often paired with other pain medications such as NSAIDs, opioids, or gabapentin.

Its use in cats and dogs to treat pain 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 amantadine given?

Amantadine is given by mouth in the form of a capsule, tablet, or liquid solution. It can be given with or without food, but if your pet vomits after receiving the medication on an empty stomach, try giving it with a small meal or treat.

This medication can take a few weeks before full effects are obvious, but side effects can occur immediately. Gradual improvements are usually noticed after a few days.

What if I miss giving my pet the medication?

If you miss a dose, give it when you remember, but if it is close to the time for the next dose, skip the dose you missed and give it at the next scheduled time, and return to the regular dosing schedule. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

Information on side effects in cats and dogs are not well known. Possible side effects include agitation, soft stools, diarrhea, and gassiness. At toxic doses, side effects include tremors, anxiety, incoordination, and increased salivation and vomiting.

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?

Risk factors in cats and dogs are not well known or described. Based on information for use of this medication in humans, avoid using this medication in pets that are allergic to it or have untreated glaucoma. Use with caution in pets with liver or kidney disease, congestive heart failure, eczematoid dermatitis, or seizures. This medication should be used with extreme caution in pregnant or nursing pets.

Are there any drug interactions I should be aware of?

The following medications should be used with caution when given with amantadine: anticholinergic drugs, CNS stimulants (includes selegiline), trimethoprim/sulfa, quinidine, quinine, thiazide diuretics, triamterene, or urinary acidifiers.

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?

There is no specific monitoring that needs to be done while your pet is taking this medication aside from watching for adverse effects. Your veterinarian may monitor your pet to be sure that the medication is working.

How do I store amantadine?

All forms of this medication should be stored in a tight container at room temperature, with short exposures to temperatures as low as 15°C (59°F) and as high as 30°C (86°F) permitted. Do not freeze the oral solution.

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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