Amantadine: veterinary dose and monograph

At a glance

Drug class

Analgesic

Also known as

Symmetrel, Amantrel, Comantrel

Species with doses

Dogs, Cats and Ferrets

General dose range

3–5 mg/kg PO q12–24h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Chronic osteoarthritis pain refractory to NSAID alone (add-on)
• Neuropathic / central-sensitisation ("wind-up") pain (multimodal)
• Cancer pain (adjunct)
• Post-surgical maladaptive pain

Amantadine dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Chronic/neuropathic pain (adjunct): Plumb’s p.62: 3–5 mg/kg PO once daily added to an NSAID for osteoarthritis (Lascelles 2008; Gaynor); to reduce wind-up 3–5 mg/kg once daily for a week. Papich 5e: 3–5 mg/kg q12h PO. Reduce in renal disease.

Cats

• Chronic/neuropathic pain (adjunct): Papich 5e: 3 mg/kg q24h PO, up to 5 mg/kg in some cases. Plumb’s p.62: 3 mg/kg once daily (Lascelles 2003; Hardie 2006); 3–5 mg/kg once daily (Gaynor). Toxicity not evaluated in cats; reduce in CKD.

Ferrets

• Chronic / neuropathic pain (adjunct): Carpenter's 6th ed (Ferret analgesic table): 3–5 mg/kg PO — NMDA-antagonist adjunct that may potentiate other analgesics (opioids/NSAIDs) for chronic pain.

Contraindications

Significant renal impairment (renally excreted — accumulation). Concurrent serotonergic drugs at high combined load (caution). Seizure disorders (use cautiously). Known hypersensitivity. Not an effective sole analgesic.

Species-specific warnings

Cats: Useful feline chronic-pain adjunct; reduce dose in CKD cats (renally excreted) and monitor for GI upset/agitation.

Adverse effects

• GI upset (transient, often resolves in a few days)
• Agitation / behavioural change
• Diarrhoea, flatulence
• Rare: ataxia at higher doses

Drug interactions

• Serotonergic drugs (SSRIs, TCAs, tramadol, MAOIs/selegiline): additive serotonergic effects — caution
• Anticholinergics / CNS stimulants: additive CNS effects
• Renally excreted — care with other renally cleared drugs in CKD

Pregnancy and lactation

Limited veterinary data; teratogenic in some lab studies — avoid in pregnancy unless clearly needed.

Monitoring

• Analgesic response over 1–2 weeks (effect is gradual and additive)
• Renal function (dose adjustment in CKD)
• Behaviour/GI tolerance early in therapy
• Overall multimodal-protocol response

Toxicity and overdose

Wide margin at therapeutic doses; overdose causes agitation, GI upset, ataxia, and at high doses CNS stimulation/anticholinergic-type signs (tremor, tachycardia, possibly seizures). Accumulates in renal impairment.

Management: No specific antidote. Supportive — fluids to support renal clearance, manage agitation/tremor (benzodiazepines), monitor cardiac rhythm. Decontaminate large recent ingestions. Effects resolve as the drug is cleared.

Clinical pearls

• A pain "potentiator," not a stand-alone analgesic — add it to an NSAID (± gabapentinoid/opioid) for refractory osteoarthritis or neuropathic pain
• Targets central sensitisation/wind-up — most useful when pain has become chronic and poorly NSAID-responsive
• Give it time: benefits build over days to a couple of weeks
• Reduce the dose in renal-impaired patients (renally excreted) and watch for transient GI upset early on

Mechanism of action

Non-competitive antagonist of the N-methyl-D-aspartate (NMDA) glutamate receptor in the dorsal horn of the spinal cord. By blocking NMDA-mediated central sensitisation ("wind-up"), it reduces amplification of nociceptive signalling — diminishing chronic/neuropathic pain and restoring responsiveness to other analgesics (NSAIDs, opioids). It also has weak dopaminergic/antiviral actions unrelated to its analgesic use.

Formulations and products

• 100 mg capsule/tablet
• Syrup 10 mg/mL (50 mg/5 mL)
• Amantrel — 100 mg capsule; 50 mg/5 mL syrup, Capsule / syrup (human-label)
• Comantrel — 100 mg tablet, Tablet (human-label)

Storage

Capsules/syrup: 15–30 °C, dry, protect from light.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other analgesics

• Aspirin
• Bupivacaine
• Buprenorphine
• Butorphanol
• Codeine
• Dipyrone (Metamizole)
• Fentanyl
• Gabapentin

Frequently asked questions