Pexion® (Imepitoin) Dosage Calculator For Dogs
Estimate a starting-point oral dose based on your dog’s bodyweight. Always confirm any dose with your veterinary surgeon.
Dosage Results
- Give doses roughly 12 hours apart, at consistent times relative to feeding, twice daily.
- The recommended starting dose is 10 mg/kg twice daily; if seizures are not adequately controlled after at least one week, a vet may raise the dose in 50–100% increments up to a maximum of 30 mg/kg twice daily.
- Never start, stop, or change a Pexion dose without direct veterinary guidance.
- Not recommended for male breeding dogs or for female dogs during pregnancy or lactation — consult your vet.
This tool provides a reference calculation only and does not replace professional veterinary advice.
When your dog is just diagnosed with idiopathic epilepsy or your vet has recommended Pexion Dosage for your Dogs firework season, you're likely to have one question on your mind more than any other; how much do I actually give?
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In brief, Pexion (imepitoin) is dosed according to your dog's weight, and the dosage varies if it is for epilepsy or noise phobia. The dose is not the same for everyone and this medicine can only be prescribed by your vet who will determine and adjust the dose, depending on how your dog responds.
This guide explains the official weight-based dose chart and how vets calculate starting and maximum doses, what to do if a dose is missed and the side effects and warning signs all owners must be aware of. The following dosage amounts are from the manufacturer's Pexion dosage for dogs product information sheet (datasheet) as published on the NOAH Compendium of UK product information sheets (UK product datasheet) by Boehringer Ingelheim.
Important: This article is not for advice purposes. It is not a substitute for veterinary advice. Your vet is the only one who can start, adjust and prescribe a dose of Pexion for your dog.
Quick Facts
| Drug name | Imepitoin (brand name: Pexion) |
| Drug class | Low-affinity partial agonist at the benzodiazepine site of the GABA-A receptor |
| Used for | Idiopathic epilepsy (seizure control); noise aversion/phobia in dogs |
| Form | 100 mg and 400 mg scored tablets |
| Epilepsy dose range | 10–30 mg/kg, twice daily |
| Noise phobia dose | 30 mg/kg, twice daily |
| Prescription status | Prescription-only veterinary medicine |
| Manufacturer | Boehringer Ingelheim |
What Is Pexion (Imepitoin)?
Pexion is the brand name for a prescription anti-anxiety and anticonvulsant drug for dogs called imepitoin. It acts by binding to the brain's GABA-A receptors, which increase the threshold needed for a seizure to occur and have a calming effect on the nervous system, similar to the effect of benzodiazepines.
Vets prescribe it for two reasons:
- Idiopathic epilepsy (recurrent seizures when there is no known cause) to make it less frequent.
- Noise aversion or noise phobia – fear responses to fireworks, thunderstorms, or other loud or sudden noises.
Imepitoin medication for dogs is not metabolized in the liver in a manner that frequently leads to chronic liver damage as is the case with phenobarbital, and does not need to be monitored routinely in the bloodstream like older anticonvulsants. It's a significant factor in its growing status as a first-line treatment since its approval for canine epilepsy.
Pexion Dosage Chart for Dogs (Official Dosing)
Weight is only part of the dose used to treat a condition. The two official dosing tables, from Pexion's datasheet in the UK.
Dosage for Idiopathic Epilepsy
The usual Pexion for dogs starting dose is 10mg/kg twice a day, approximately 12 hours apart. Dose may be increased in 50–100% increments by a vet, if seizures are not well controlled, up to a maximum of 30 mg/kg twice daily, after at least one week.
Starting-dose tablet chart (twice daily):
| Bodyweight (kg) | 100 mg tablets | 400 mg tablets |
| Up to 5.0 kg | ½ tablet | — |
| 5.1 – 10.0 kg | 1 tablet | — |
| 10.1 – 15.0 kg | 1½ tablets | — |
| 15.1 – 20.0 kg | — | ½ tablet |
| 20.1 – 40.0 kg | — | 1 tablet |
| 40.1 – 60.0 kg | — | 1½ tablets |
| Over 60 kg | — | 2 tablets |
Tablets can be split for accurate dosage. If the half tablet is left over, it must be taken at the next dose and not discarded.
Dosage for Noise Phobia (Fireworks, Storms, etc.)
However, Pexion Dose for the fear of noise, the dose is set at 30 mg/kg twice daily (as in epilepsy) due to the fact that a more powerful anxiolytic effect is desired for short-term use. Treatment should begin two days prior to the anticipated noisy event and be continued during the event.
Starting-dose tablet chart (twice daily):
| Bodyweight (kg) | 100 mg tablets | 400 mg tablets |
| Up to 5.0 kg | ½ tablet | — |
| 5.1 – 10.0 kg | 1 tablet | — |
| 10.1 – 15.0 kg | 1½ tablets | — |
| 15.1 – 20.0 kg | — | ½ tablet |
| 20.1 – 40.0 kg | — | 1 tablet |
| 40.1 – 60.0 kg | — | 1½ tablets |
| Over 60 kg | — | 2 tablets |
The Pexion Dose for your dog is not merely a chart to lookup - it's actually calculated.The Pexion Dose isn't just a chart look-up, it is actually calculated.
Noise phobia tablet chart (twice daily):
| Bodyweight (kg) | 100 mg tablets | 400 mg tablets |
| 2.5 – 3.9 kg | 1 tablet | — |
| 4 – 5.9 kg | 1½ tablets | — |
| 6 – 7.9 kg | 2 tablets | — |
| 8 – 10.9 kg | 3 tablets | — |
| 11 – 15.9 kg | — | 1 tablet |
| 16 – 22.9 kg | — | 1½ tablets |
| 23 – 29.9 kg | — | 2 tablets |
| 30 – 36.9 kg | — | 2½ tablets |
| 37 – 43.9 kg | — | 3 tablets |
| 44 – 49.9 kg | — | 3½ tablets |
| 50 – 55.9 kg | — | 4 tablets |
| 56 – 71.9 kg | — | 4½ tablets |
| 72 – 80 kg | — | 5 tablets |
How the Pexion Dose Is Calculated (Not Just a Chart Lookup)
- The severity of the condition. If a dog has a severe and frequent seizure, he might begin at the higher end of the range; if he has mild, infrequent seizures, then he might start lower.
- Response over time. Vets usually wait at least a week at the same dosage before making a decision on increasing it as imepitoin takes time to take its full effect.
- Bioavailability and feeding. Imepitoin is best absorbed when given on an empty stomach and it is generally advised to be given at the same time each day in relation to a meal (usually before a meal for epilepsy).
- Concurrent health issues. Liver, kidney or heart damage disease dogs are treated separately – see the Contraindications section below.
Worked example: If a dog started an epilepsy treatment at 10mg/kg and the dog weighed 22kg, then the dog would receive a 10mg/kg x 22kg = 220mg — this would be rounded to one 400mg tablet twice a day as per the above chart. If seizures persist after 1 week, the veterinarian may increase the dose to 15–20 mg/kg (1.5 tablets) per dose, always within the 10–30 mg/kg dose range.
This is why a generic online calculator can only ever provide you with a starting point: the actual amount is a clinical judgment that your vet makes and can tweak to the response of your dog.
How Long Does Pexion Take to Work?
Imepitoin usually begins to work within 1–2 hours of giving it, but it may not be obvious that there is anything different about your dog at this point. The vets recommend that one give the medicine two days in advance in case of noise phobia, giving it time to get to a more stable effect before the stressful event occurs.
What If You Miss a Dose?
If a dose is missed, take it as soon as you remember and then restart the twice daily dosing routine as usual. Avoid doubling the dose for a missed dose as this increases the risk of side effects and does not provide greater protection against seizures.
Side Effects of Pexion in Dogs
While most side effects are mild and die down as your dog's body acclimates itself, it's important to understand what’s common and what’s rare, so you can know when to call your vet.
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Common Side Effects (Epilepsy Dosing)
- Ataxia (wobbliness, poor co-ordination) and drowsiness - typically mild and transient
- Vomiting
- Aid in appetite, particularly at the beginning of the treatment period.
- Hyperactivity
- Loss of appetite, thirst or urination
- Excess salivation or diarrhea
Common Side Effects (Noise Phobia Dosing)
- Lacks of coordination and a voracious appetite
- Lethargy
- Vomiting
Uncommon to Rare Side Effects
- Aggression, disorientation (can be due to the underlying seizure disorder and not just to the drug)
- Improved hearing abilities
- Anxiety
- Minor and generally inconsequential bloodwork abnormalities in the kidneys
When to Call Your Vet Immediately
- Signs of allergic reaction: swelling of face, rash, fever or difficulty breathing
- Rapidly escalated aggression
- Seizures that seem to be getting worse or more frequent, not fewer
- Any symptom that seems serious, does not improve or that concerns you
Pexion Contraindications: When It Shouldn't Be Used
Your veterinarian will test for these prior to prescription. Dogs should not be treated with Pexion dosage if they:
- Have a known sensitivity to imepitoin or any of the components of the tablet.
- Have significant liver, kidney or heart disease
Use with extra caution and closer vet oversight in dogs that:
- Have a weight under 2kg (safety has not been established below this weight)
- Become pregnant or nursing (not recommended)
- Are for breeding — male dogs given very high overdoses in safety studies had reduced sperm counts and changes in their testicles, so it is important to have a specific conversation with your veterinarian if you have a male dog that you are thinking about breeding with
- Have a history of aggression – imepitoin works on the same receptor pathway as benzodiazepines, which can sometimes exacerbate fear-based aggression in predisposing dogs.
Drug Interactions
Before beginning Pexion dosage treatment, be sure to tell your vet about any other medications, supplements or herbal products your dog is taking. Known interaction points are:
- Phenobarbital, potassium bromide, and levetiracetam: Available data do not indicate any harmful interactions between Pexion and these anticonvulsants, although information on the effectiveness of Pexion as an add-on therapy (not used alone) is limited.
- Flumazenil — there is caution to combine as it also acts on the same receptor system.
- Epilepsy drugs must not be abruptly changed; any changes must be made slowly and only under veterinary supervision.
What Happens With an Overdose?
Manufacturer's safety data indicated that repeated doses of up to 5 times the maximum recommended dose resulted in central nervous system effects (loss of coordination, drowsiness, eyelid droop, eye watering), gastrointestinal upset, and a reversible change in heart rhythm (QT prolongation) in dogs. All these effects were not life-threatening and were reversible within 24 h with supportive therapy.
If you think your dog has overdosed on Pexion, either through an error in dosage or getting into the bottle, call your vet or an emergency animal hospital right away. Do not wait and watch for symptoms.
In humans: If accidentally ingested it can lead to lethargy, nausea and dizziness. In case of accidental ingestion of Pexion tablets by a child or adult, please consult a physician at once and bring the packaging with you.
Pexion vs. Other Canine Epilepsy Medications
| Feature | Pexion (Imepitoin) | Phenobarbital | Potassium Bromide |
| Dosing frequency | Twice daily | Twice daily | Once or twice daily |
| Routine bloodwork needed | Not typically required for the drug itself | Yes — regular liver and blood-level checks | Yes — regular blood-level checks |
| Onset of effect | Fast (near-immediate seizure threshold effect) | Takes 1–2 weeks to reach steady blood levels | Takes weeks to months to reach steady levels |
| Sedation | Mild, often improves with time | Can be more pronounced, especially early on | Can be pronounced |
| Liver impact | Minimal | Higher long-term liver-related risk | Minimal liver impact, but can affect the pancreas |
| Typical use case | First-line for mild-to-moderate epilepsy; noise phobia | Often first-line for more severe or poorly controlled epilepsy | Usually add-on therapy |
Only for general orientation — the right med (or combination) will depend upon your dog's individual case and only your vet can make that call.
Monitoring While Your Dog Is on Pexion
- Maintain a seizure diary: date, time, length of seizure, what happened before/after. This one tip is the most important to give your veterinarian when deciding to adjust the dose.
- Monitor for side effects for the first 1-2 weeks as this is when they are most likely to occur.
- Do not skip vet visits after your dog has been treated, even if it appears that your canine is feeling much better.
- Do not withdraw from the drug suddenly — some dogs will exhibit slight behavioral and/or muscular changes if Pexion is stopped suddenly, so any change in therapy should be made in consultation with your veterinarian.
Storage Tips
- Tablets should be stored at room temperature (about 20-25°C / 68-77°F) out of direct light.
- Between uses, keep the bottle capped as imepitoin is a controlled-access drug; children and other pets may experience dizziness and nausea if they ingest this drug.
- Do not allow children or other family pets to come in contact with it.
Myth vs. Fact
| Myth | Fact |
| "Pexion needs regular blood tests like phenobarbital." | Routine blood-level monitoring isn't a standard requirement for imepitoin itself, though your vet may still run periodic general health bloodwork. |
| "More Pexion means fewer seizures, so more is always better." | Doses are capped at 30 mg/kg twice daily for a reason — going beyond the prescribed dose increases side-effect risk without proven extra benefit. |
| "You can use the noise phobia dose for everyday epilepsy control." | The noise phobia dose is deliberately higher and meant for short-term use around a specific event, not daily long-term epilepsy management. |
| "If my dog seems fine, I can skip a dose." | Skipping doses can let seizure activity return, even if your dog looks outwardly normal in between. |
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FAQs
What is Pexion used for in dogs?
Pexion (imepitoin) treats dogs with idiopathic epilepsy to control their seizures and treats dogs that are too afraid or stressed by noises (fireworks or thunderstorms) to reduce fear and anxiety.
How much Pexion dosage should I give my dog?
The dose will be determined by your dog's weight and what condition you're treating: 10-30 mg/kg twice a day for epilepsy or 30 mg/kg twice a day for noise phobia. The actual dosage is decided and adjusted by your veterinarian.
Do I need a vet's prescription for my dog to take Pexion dose?
No. Pexion is a veterinary prescription-only medicine and should only be prescribed and dosed under the supervision of a licensed veterinarian.
How much time will Pexion require to come in?
It usually begins to act on the nervous system in 1-2 hours after a dose, but takes days to weeks of regular doses to achieve the full anti-seizure effect.
What are the safety issues with long-term use of Pexion?
Many dogs remain on Pexion long term to control epilepsy and studies have not indicated a tolerance (i.e. loss of effect) following long term treatment. You should still have your vet monitor your pet for long-term use.
What happens if I miss a dose of Pexion?
If you forget, give it as soon as you remember, and resume the regular schedule. Don't give a double dose.
Can Pexion be given with food?
It can, but imepitoin is absorbed better when given on an empty stomach. It is typically advised to be administered before feed and at the same time each day.
Are dogs aggressive when taking Pexion medication?
This is a rare but possible side effect, as imepitoin acts on a receptor pathway that can sometimes disinhibit fear-based behaviors. For dogs that have previously been aggressive, it's important to have a careful examination by the vet before beginning.
What is the difference between Pexion and phenobarbital?
They are from different families of drugs. Generally Pexion will have a more rapid onset and will not need to be maintained on the same routine blood monitoring as phenobarbital; however, phenobarbital may be more effective in some dogs with severe and/or poorly controlled epilepsy, and the risk of liver toxicity is lower with Pexion.
Is Pexion safe for dogs in heat or lactating?
Not recommended in pregnant and lactating dogs. Discuss other options with your vet if your dog is in heat, pregnant, or breeding.
If my dog eats too much Pexion, what should I do?
Even if your dog appears to be fine, call your veterinarian or emergency animal hospital right away.
Are there any drug interactions with Pexion?
It is compatible with phenobarbital and potassium bromide as well as levetiracetam, but any changes to his drugs should be monitored by your veterinarian.
What are the differences between Pexion for noise phobia and epilepsy?
Epilepsy dosing is low (10 mg/kg) and increased over time for long-term use, whereas noise phobia is a fixed dosage (30 mg/kg) and is used for a short period of time.
Key Takeaways
- Pexion (imepitoin) for dogs is dosed twice a day by weight for each of the conditions: epilepsy 10–30 mg/kg twice a day; noise phobia 30 mg/kg twice a day.
- The dose on the chart is intended as a starting point – your veterinarian will adjust this dose as needed by the response of your dog.
- Never make up a missed dose and never discontinue the drug without veterinary advice.
- Be alert to wobbliness, drowsiness and changes in appetite; most side effects are minor but facial swelling, breathlessness or increased seizures require immediate veterinary care.
- Dose changes or initiations/terminations of Pexion should only be done by a licensed veterinarian.
Final Thoughts
Pexion is one of the most owner-friendly treatments for canine epilepsy and noise-related anxiety because, once a correct dosage has been established by your vet, it's easy to administer, and it doesn't require as much monitoring as older anticonvulsants. However, "straightforward" does not imply "do it yourself.
The dosing charts listed above are the official figures your vet follows, use them to learn what to expect from the dose and to ask more intelligent questions at your vet's office, but don't use them to selfdiagnose and self-treat with the dose.
Your vet, not a guess, should be called if your dog's seizures are not improving, side effects appear to be significant, or if you ever doubt the dosage.
