Cenobamate (Xcopri)

How Medicare covers it

Part D (forms used at home). Part A during a covered inpatient stay. No Part B clinician-administered form in the CMS Part B spending file.

What it treats

Partial-onset seizures (seizures that start in one part of the brain) in adults.

What it is for, in depth

Cenobamate (Xcopri) is a seizure medicine for adults with partial-onset seizures — seizures that begin in one part of the brain, with or without spreading. Per the label's Indications section, it is prescribed for adults only; safety and use in children have not been established. It fits the treatment path as a once-daily add-on or single therapy for partial-onset seizures that need another option, and its dose is raised very slowly — no faster than the label's schedule — because rapid increases were linked to the serious DRESS reaction. It comes as film-coated tablets in 12.5 mg (titration packs), 25 mg, 50 mg, 100 mg, 150 mg, and 200 mg strengths, plus titration and maintenance blister packs that lay out the slow dose climb.

How it works

The label says the exact way cenobamate works is not known. It has been shown to reduce repeated firing of brain nerve cells by blocking voltage-gated sodium currents, and it boosts the action of GABA, a calming brain chemical, at its GABA-A channel.

How it is taken

Taken by mouth once a day, with or without food. Treatment starts low at 12.5 mg once daily and rises slowly on the label's titration schedule to a usual maintenance dose of 200 mg once daily; the maximum is 400 mg once daily. The titration schedule should not be sped up. Tablets can be swallowed whole or crushed and mixed with water.

Common side effects

In the label, the most common problems are sleepiness (somnolence), fatigue, dizziness, balance and coordination problems, and thinking problems such as confusion. MedlinePlus also lists headache, tiredness, nausea, vomiting, diarrhea, constipation, dry mouth, taste changes, heartburn, stomach pain, loss of appetite, weight loss, and back pain.

Serious warnings

Cenobamate can cause DRESS, a serious drug reaction with rash, fever, and organ involvement — a faster-than-recommended titration raises this risk, and the drug is stopped if no other cause is found. It can shorten the heart's QT interval, cause liver injury (liver blood tests are checked before starting and during treatment), and, like other seizure drugs, may raise the risk of suicidal thoughts or behavior. Stopping it suddenly can bring on more seizures, so it is withdrawn gradually.

Who should be careful

People with familial short QT syndrome must not take cenobamate — it is contraindicated for them, as it is for anyone allergic to it. People with liver problems take lower maximum doses, and use is not recommended in severe liver disease or in end-stage kidney disease on dialysis. Kidney problems call for caution and possibly a lower dose. Based on animal data, it may harm an unborn baby.

Major interactions

Cenobamate changes the levels of several other drugs: phenytoin levels rise (its dose may need to be cut by up to half), phenobarbital and clobazam doses may need lowering, and lamotrigine and carbamazepine doses may need raising. It can also raise or lower levels of drugs processed by the CYP2B6, CYP3A, and CYP2C19 liver enzymes, and it can make hormonal birth control pills less effective, so women should use extra or non-hormonal birth control. Alcohol and other sedating drugs add to its sleepiness effects.

Cost and saving notes

Cenobamate is sold only as the brand name Xcopri — there is no generic version in the formulary data, which is one reason plans place it on a higher tier. If you have limited income, Extra Help (the Part D Low-Income Subsidy) can lower Part D drug costs, and you can ask your plan about a tier exception if the copay is too high.

Why it is in its tier

Cenobamate (Xcopri) sits on Tier 5 in 92.99% of the plans that list it (5110 of 5495 listing plans). Tier 5 is the specialty tier — instead of a flat copay, patients usually pay a percentage of the drug's cost (coinsurance), which is why specialty drugs feel expensive even with coverage. The data-visible drivers: It is a brand-only product with no generic version in the formulary data, and the CMS dashboard puts its average Part D spending at about $13,176 per beneficiary for 2024 — a high-cost drug, which matches where plans place it. It is listed by 100.0% of Part D plans. The tier shown is the most common one; individual plans vary.

Sources

• XCOPRI TITRATION PACK (CENOBAMATE) KIT XCOPRI (CENOBAMATE) TABLET, FILM COATED XCOPRI MAINTENANCE PACK (CENOBAMATE) KIT XCOPRI (CENOBAMATE) TABLET [SK LIFE SCIENCE, INC.] — DailyMed
• MedlinePlus — National Library of Medicine
• MedlinePlus

What official patient guides say

Take cenobamate once a day at about the same time each day, with or without food; if you cannot swallow the tablet whole, it can be crushed and mixed with water. Your doctor will start you on a low dose and raise it slowly, no more than once every 2 weeks. It can make you dizzy, sleepy, and unsteady, so do not drive or do activities that need alertness until you know how it affects you. If you miss a dose, take it as soon as you remember unless it is almost time for the next dose — then skip it and never double up. Do not stop taking it suddenly without talking to your doctor, because seizures can get worse. Store it in its container, tightly closed, at room temperature away from extra heat and moisture (not in the bathroom).

Source: MedlinePlus

Part D formulary coverage

Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.

What you pay

Without insurance, the cash benchmark is 39.85734 per unit (XCOPRI 100 MG TABLET) — about nan for 30 units. NADAC benchmark — the average price pharmacies pay (CMS, as of 2026-11-04). Pharmacy shelf prices vary.

A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.

Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-07

Coverage by plan and tier

Of the 5,495 Medicare drug plans we track for 2027, 5,495 list Cenobamate (Xcopri) — 100% of plans. Most of those plans put it on Tier 5: 5,110 plans, 93.0% of the plans that list it. Other plans place it on Tier 4 (261 plans), Tier 1 (123 plans) or Tier 2 (1 plans). For example: Aetna Medicare Dual Extra (HMO D-SNP) puts it on Tier 5; Aetna Medicare Dual Extra Care (PPO D-SNP) puts it on Tier 5; Aetna Medicare Value Plus (PPO) puts it on Tier 5. You can compare these plans side by side on our Medicare Advantage hub. A tier is not a price. What you pay also depends on whether you have met your plan';s deductible, whether the drug costs a flat copay or a share of the price, and whether you get Extra Help or Medicaid.

Read next

• Part D in 2027: The $700 Deductible, the $2,400 Cap, and the $35 Insulin Rule
• Extra Help in 2027: Lower Drug Copays and Who Qualifies
• Checking Medicare Savings Programs and Extra Help

Part D spending averages (2024)

Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30

Companies covering this drug

Part D and Medicare Advantage plan sponsors that list this drug on a formulary, 50 at a time.