Imepitoin: veterinary dose and monograph

At a glance

Drug class

Veterinary drug

Also known as

Pexion

Species with doses

Dogs and Cats

General dose range

10–30 mg/kg PO q12h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Canine idiopathic epilepsy — first-line/monotherapy for mild-to-moderate seizure frequency
• Reduction of generalised seizure frequency (with or as alternative to phenobarbital)
• Noise (fear) aversion / phobia (licensed in some markets)

Imepitoin 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

• Idiopathic epilepsy: Papich 5e: 10–30 mg/kg PO q12h. Pexion label: start at 10 mg/kg q12h; if control is inadequate after at least 1 week, increase in 50–100% steps up to 30 mg/kg q12h. Taper to stop. Plumb’s 10e p.638 (extra-label in the US): initially 10 mg/kg PO twice daily (≈12 h apart); if seizure frequency is not adequately reduced after at least 1 week, increase in 50–100% increments to a maximum of 30 mg/kg twice daily. Papich 5e gives no cat dose; Plumb’s 10e does (see Feline row).
• Noise aversion (event-based): Papich 5e: 30 mg/kg PO q12h (whole and half tablets), starting 2 days before the expected noise event and continuing through it. Plumb’s 10e p.638 (label dosage; FDA-approved): the same regimen.
• Storm anxiety (continuous): Plumb’s 10e p.638 (extra-label): storm anxiety — 30 mg/kg PO every 12 hours, given continuously rather than as needed.

Cats

• Idiopathic epilepsy: Plumb’s 10e p.639 (extra-label): 30 mg/kg PO every 12 hours has been reported in cats and appears well tolerated, but data are limited. Papich 5e gives no cat dose.

Contraindications

Severe hepatic, renal or cardiovascular impairment (limited data). Known hypersensitivity. Not ideal as sole therapy for severe/frequent or cluster seizures (phenobarbital/bromide may be more effective there). Abrupt discontinuation (taper). Pregnancy (limited data).

Species-specific warnings

Dogs: May be insufficient as sole therapy for severe or cluster epilepsy — assess response over ~1–2 weeks and add/switch to phenobarbital/bromide if control is inadequate.

Adverse effects

• Transient sedation, ataxia, polyphagia/weight gain (often early and self-limiting)
• Polydipsia, hyperactivity/restlessness
• Vomiting, hypersalivation
• Generally fewer/milder effects than phenobarbital

Drug interactions

• Other CNS depressants: additive sedation
• Minimal hepatic enzyme induction (few pharmacokinetic interactions — an advantage over phenobarbital)
• Can be combined with phenobarbital/bromide as add-on therapy

Pregnancy and lactation

Safety in breeding/pregnant/lactating dogs not established — avoid unless clearly needed (uncontrolled epilepsy is itself dangerous).

Monitoring

• Seizure frequency/severity (efficacy) — the primary monitor; NO blood-level or routine liver monitoring needed
• Early transient sedation/ataxia/polyphagia (usually settles in 1–2 weeks)
• Body weight (polyphagia)
• Taper when discontinuing

Toxicity and overdose

Wide safety margin and well tolerated; overdose mainly causes sedation, ataxia and increased appetite. No characteristic organ toxicity, and (a major advantage) it does not require the liver/level monitoring of phenobarbital. Severe/cluster epilepsy may simply respond inadequately — a treatment limitation rather than toxicity.

Management: No specific antidote. Supportive care — confine to prevent ataxia-related injury; effects resolve as the drug is cleared. (Flumazenil, a benzodiazepine-site antagonist, would theoretically oppose it but is not routinely required.) Do not stop abruptly after chronic use — taper.

Clinical pearls

• A modern first-line canine epilepsy drug with real practical advantages: fast full onset (no long titration), NO therapeutic-level or routine liver monitoring, minimal interactions, and a gentle side-effect profile
• Best for mild-to-moderate epilepsy — severe/frequent or cluster seizures may need phenobarbital/bromide (or imepitoin as an add-on)
• Early sedation/ataxia/increased appetite are common but usually transient — reassure owners
• Twice-daily dosing; taper rather than stop abruptly
• Also licensed for noise-aversion/fear of loud events in some markets

Mechanism of action

A low-affinity PARTIAL agonist at the benzodiazepine binding site of the GABA-A receptor, modestly enhancing GABA-mediated inhibitory neurotransmission to raise the seizure threshold; it also has weak calcium-channel-blocking activity. The "partial" agonism gives anticonvulsant/anxiolytic effects with less sedation and (unlike full benzodiazepine agonists) no clinically relevant tolerance or dependence, and it is minimally hepatically inducing.

Formulations and products

• 100 mg tablet (Pexion)
• 400 mg tablet (Pexion)
• Pexion (Boehringer Ingelheim) — 100 / 400 mg tablet, Tablet

Storage

Tablets: 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 hormones, emergency drugs, supplements and other drugs

• Hydrocortisone (Cortisol)
• Hydroxyprogesterone Caproate
• Hydroxyzine
• Hypertonic Saline (7.2–7.5% NaCl)
• Insulin
• Intravenous Lipid Emulsion (ILE)
• Iron Dextran
• Leflunomide

Frequently asked questions