Imepitoin
1-(4-chlorophenyl)-4-(4-morpholinyl)-2,5-dihydro-1H-imidazol-2-one
Also known as: Pexion · AWD 131-138
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Idiopathic epilepsy — reduction of generalised seizure frequency | 10 mg/kg initially, titrated up to max 30 mg/kg | PO | q12h (approx. 12 h apart) | Long-term | 🌍 EU |
| Noise phobia — reduction of anxiety and fear | 30 mg/kg | PO | q12h (approx. 12 h apart) | Start 2 days before the expected noise event and continue through it | 🌍 EU |
- Idiopathic epilepsy — reduction of generalised seizure frequency: If seizures are not adequately reduced after at least 1 week at the current dose, the dose may be increased in 50–100% increments to a maximum of 30 mg/kg q12h. Bioavailability is greater in fasted dogs — keep timing relative to feeding consistent. Not tested in dogs under 2 kg.
- Noise phobia — reduction of anxiety and fear: Efficacy not tested in dogs younger than 12 months. Claim is based on a 3-day course for a fireworks noise event.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Imepitoin is a centrally acting antiepileptic drug primarily used in veterinary medicine for the management of idiopathic epilepsy in dogs, as well as for the treatment of noise phobia. Unlike traditional antiepileptics like phenobarbital, it has a lower risk of hepatotoxicity and does not typically induce liver enzymes to the same extent.
Clinical Pearl: Imepitoin is often preferred for dogs with mild to moderate idiopathic epilepsy due to its favorable side effect profile, but it may not be sufficient as a monotherapy for severe or cluster seizures.
Mechanism of action
Imepitoin inhibits seizures via potentiation of the GABA_A receptor-mediated inhibitory effects on the neurons. It acts as a low-affinity partial agonist at the benzodiazepine site of the GABA_A receptor → hyperpolarization of the neuronal membrane → decreased neuronal excitability.
Imepitoin also has a weak calcium-channel blocking effect, which may contribute to its anticonvulsive properties.
Safety & warnings
Contraindications
- Severely impaired hepatic function
- Severe renal disorders
- Severe cardiovascular disorders
- Status epilepticus
- Cluster seizures (as primary monotherapy)
Adverse effects
- Polyphagia
- Hyperactivity
- Polyuria
- Polydipsia
- Somnolence
- Hypersalivation
- Emesis
- Ataxia
Precautions
Warning: Not recommended as a primary treatment for status epilepticus or cluster seizures.
Sudden withdrawal of antiepileptic therapy may precipitate seizures; taper gradually if discontinuing.
Clinical Pearl: Efficacy may take several days to weeks to fully assess. Monitor patients closely during the transition from other antiepileptic drugs.
Drug interactions
May have additive CNS depressant effects
Additive sedation and CNS depression
Monitoring
- Seizure frequency and severity
- Routine blood work (CBC, serum biochemistry) periodically
Pharmacokinetics
Half-life
Absorption
Rapidly and almost completely absorbed after oral administration.
Distribution
Wide distribution, readily crosses the blood-brain barrier.
Metabolism
Extensively metabolized in the liver.
Elimination
Primarily excreted via feces/biliary route.
Overdose
Overdosage is generally well tolerated up to 5 times the recommended dose.
Clinical signs of overdose may include severe ataxia, somnolence, salivation, and vomiting.
Clinical Pearl: Treatment is largely supportive and symptomatic, as there is no specific antidote. Due to its rapid elimination, signs usually resolve quickly once the drug is discontinued or metabolized.
Available products
Formulations
- 100 mg oral tablet
- 400 mg oral tablet
Veterinary
- Pexion 100 mg tablets
- Pexion 400 mg tablets
Regulatory status
Approved in the US specifically for noise aversion in dogs.
Approved for canine idiopathic epilepsy and noise phobia.
POM-V classification.
No regulatory data for: 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store in the original package to protect from moisture. No special temperature storage requirements.
Client information
Imepitoin is used to control seizures or manage noise phobia in dogs.
- Consistency is key: Give the medication at the same times each day. It can be given with or without food, but choose one method and stick to it.
- Do not stop abruptly: Suddenly stopping this medication can cause severe seizures.
- Side effects: You may notice increased appetite, mild sleepiness, or hyperactivity when starting the medication. These often resolve as your dog adjusts to the drug.
- Contact your veterinarian if seizures worsen or if you notice severe incoordination or vomiting.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.