Anti-epileptic Pregnancy: No adequate data on the developmental risk associated with use in pregnant women; in animal studies, administration during pregnancy or throughout pregnancy and lactation caused adverse developmental effects (increased embryofetal mortality, decreased fetal and offspring body weights, neurobehavioural and reproductive impairment) at clinically relevant exposures. The source encourages enrolment in an antiepileptic drug pregnancy exposure registry.

Cenobamate

Brand names: Ontozry

Cenobamate is an antiseizure medication used as adjunctive therapy for focal (partial-onset) seizures in adults with epilepsy that is inadequately controlled by other treatments.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Initial 12.5 mg once daily (weeks 1–2), titrated to the recommended maintenance dosage of 200 mg once daily (week 11 and thereafter)

Route: Oral (tablets; may be taken whole or crushed and mixed with 25 mL water as an oral suspension by mouth or via nasogastric tube)

Frequency: Once daily, with or without food

Max: 400 mg once daily. If needed based on clinical response and tolerability, the dose may be increased above 200 mg by increments of 50 mg once daily every two weeks to 400 mg. Mild or moderate (Child-Pugh A–B) hepatic impairment: maximum recommended dosage 200 mg once daily

Source is US labelling (Xcopri, SK Life Science, label date 2025-09-25) — the eMC/UK SPC section was not present in the fetched bundle, so the UK product (Ontozry) posology must be checked before publication. Indication per the source dosing table: partial-onset seizures in adults (monotherapy and adjunctive therapy). Titration schedule, which should not be exceeded because of the potential for serious adverse reactions: weeks 1–2 12.5 mg once daily; weeks 3–4 25 mg once daily; weeks 5–6 50 mg once daily; weeks 7–8 100 mg once daily; weeks 9–10 150 mg once daily; week 11 and thereafter 200 mg once daily. Before initiating, obtain serum transaminases (ALT and AST) and total bilirubin if not available within the previous 3 months, to establish baseline liver function. Not recommended in severe (Child-Pugh C) hepatic impairment. Elderly: the source states clinical studies did not include sufficient numbers of patients aged 65 and over; dose selection should be cautious, usually starting at the low end of the dosing range. On discontinuation, reduce the dosage gradually over a period of at least 2 weeks unless safety concerns require abrupt withdrawal. Paediatric use: safety and effectiveness in paediatric patients have not been established; no paediatric dose is stated — clinician to verify against a children's formulary. Tablet strengths stated: 12.5 mg, 25 mg, 50 mg, 100 mg, 150 mg, 200 mg. Source wording: "The recommended initial dosage of XCOPRI is 12.5 mg once daily, titrated to the recommended maintenance dosage of 200 mg once daily. The recommended titration schedule should not be exceeded. The maximum dosage is 400 mg once daily."

Dose auto-extracted from US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to cenobamate or any of the inactive ingredients in the product
Familial Short QT syndrome

Side effects

Somnolence
Dizziness
Fatigue
Diplopia
Headache

Interactions

Phenytoin — potential 2-fold increase in phenytoin levels; gradually decrease phenytoin dosage by up to 50% as cenobamate is titrated
Phenobarbital and clobazam — plasma concentrations increased; reduce dosage as needed when used concomitantly
Lamotrigine and carbamazepine — plasma concentrations decreased; increase dosage as needed when used concomitantly
CYP2B6 and CYP3A substrates — increase dosage as needed when used concomitantly
CYP2C19 substrates — reduce dosage as needed when used concomitantly
Hormonal oral contraceptives — effectiveness may be reduced; women should use additional or alternative non-hormonal birth control

Clinical monograph

How it works

It is thought to reduce neuronal excitability through inhibition of persistent sodium currents and positive allosteric modulation of GABA-A receptors at a non-benzodiazepine site.

Prescribing in practice

Titrate slowly from a low starting dose because rapid titration is associated with drug reaction with eosinophilia and systemic symptoms (DRESS).
It induces and inhibits various cytochrome P450 enzymes, so review interacting drugs including other antiseizure medicines and hormonal contraception.
QT shortening can occur; use caution in those with familial short QT syndrome.

Monitoring

Monitor for hypersensitivity and DRESS during titration, alongside seizure control, sedation and interaction-related effects on co-prescribed medicines.

Counselling the patient

Follow the slow dose increase schedule exactly and do not accelerate it.
Seek urgent advice if you develop rash, fever, facial swelling or swollen glands.
Use additional or non-hormonal contraception, as this medicine can reduce the effectiveness of the contraceptive pill.

Evidence & guidelines

Cenobamate is recommended by NICE as an adjunctive option for focal seizures, supported by randomised placebo-controlled adjunctive trials.

Reference: Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways