Symmetrel (Amantadine)

Symmetrel, a human medication containing the active ingredient Amantadine, is traditionally categorised as an antiviral medication. However, it may be prescribed off-label in veterinary medicine for the management of chronic pain in dogs and cats. Symmetrel may be used in treating a range of conditions, including arthritis, neurologic pain, and pain associated with cancer in pets. Typically, Symmetrel is used in conjunction with other pain relief medications, such as NSAIDs (non-steroidal anti-inflammatory drugs) or gabapentin, to enhance pain management. It's important to note that the application of Symmetrel for pain relief in pets is considered off-label.

Amantadine functions by inhibiting the NMDA (N-methyl-D-aspartate) receptor in the nervous system, which binds to neurotransmitters responsible for pain sensation. This receptor is crucial in 'wind-up pain', where sustained pain occurs due to repeated stimulation of the nervous system. By blocking these receptors, Amantadine can reduce chronic pain, particularly when used alongside other pain control medications.

Always follow the directions provided by your veterinarian or those on the drug label. Typically, Amantadine is given twice daily, but the frequency may vary. Symmetrel can be given to pets either with or without food. However, administering the medication mixed in or disguised with food can often enhance its acceptance by the animal.

Missed Dose:

If a dose is missed, administer it as soon as remembered. However, if it's nearly time for the next dose, skip the missed one and continue with the normal schedule. Avoid giving extra or double doses.

Overdose:

Symptoms of an overdose may include tremors, breathing difficulties, lack of coordination, increased salivation, and vomiting. In such cases, immediately contact your veterinarian or the New Zealand National Poisons Centre at www.poisons.co.nz/animal-helpline/ or phone 0800 869 738.

Consult with a veterinarian for the best advice in these situations:

Known Allergy: Do not use in pets with a known hypersensitivity or allergy to amantadine.

Severe Kidney Disease: Use with caution or avoid in pets with severe renal impairment, as amantadine is primarily excreted by the kidneys and renal dysfunction can lead to accumulation of the drug.

Liver Disease: Caution is advised in pets with liver disease, although specific contraindications are less clear, the drug's metabolism may be affected.

Seizure Disorders: Use cautiously in pets with a history of seizure disorders, as amantadine may potentially lower the seizure threshold.

Pregnancy and Nursing: The safety of amantadine use in pregnant or nursing pets has not been established. Use only if the potential benefit justifies the potential risk.

Vaccination: There may be concerns regarding the use of amantadine close to the administration of live vaccines, based on its antiviral properties, although specific studies in pets are lacking.

Symmetrel is generally considered safe for dogs and cats. However, some side effects may occur, including vomiting, diarrhea, and flatulence. These side effects are usually mild and temporary. Less common side effects such as agitation, seizures, and peripheral edema may occur, so it is important to contact your veterinarian if any of these symptoms arise.

Store Symmetrel at controlled room temperatures, ensuring the container is tightly closed to protect it from moisture and light.

How long does it take for Symmetrel to work in pets?

• Consult your veterinarian as each pet is different, however they can typically show a response to the medication within a week, but it can take up to 3 weeks for full efficacy.

Can Symmetrel be used in conjunction with other medications?

• Yes, Symmetrel is often used alongside other medications, such as NSAIDs or gabapentin, to manage pain more effectively. However, always consult your veterinarian before combining medications to ensure safety and compatibility.

Is a prescription required to obtain Symmetrel for my pet?

• Yes, a prescription from a licensed veterinarian is required to obtain Symmetrel, as it must be used under veterinary supervision.