Cenobamate was approved for medical use in the United States in November 2019,[3][7][8][9] and placed in Schedule V of the Controlled Substances Act in March 2020.[10] Cenobamate was approved for medical use in the European Union in March 2021,[5] approved for use in the UK in December 2021,[11] and approved for use in Canada in June 2023.[12]
In the European Union, it is indicated for the adjunctive treatment of focal-onset seizures with or without secondary generalization in adults with epilepsy who have not been adequately controlled despite a history of treatment with at least two anti-epileptic medications.[5]
In the UK, it is used as an add-on treatment, after at least 1 other add-on treatment has not controlled seizures and only when treatment is started in a specialised epilepsy service (tertiary care).[11]
Contraindications
Cenobamate shortens the QT interval of the heart rhythm. It is therefore contraindicated in people with familial short QT syndrome, a very rare disease of the electrical system of the heart.[13][14]
There are few data regarding cenobamate overdose. It is expected that the described adverse effects such as drowsiness, dizziness and fatigue would occur, as well as possibly problems with the heart rhythm. No specific antidote exists.[13][14]
Cenobamate induces the enzymes CYP3A4 and CYP2B6 and can therefore decrease blood concentrations of drugs that are metabolized by these enzymes (for example midazolam and bupropion, respectively). Conversely, it inhibits the enzyme CYP2C19, potentially increasing concentrations of drugs metabolized by this enzyme (for example omeprazole).[13][14]
Cenobamate is absorbed from the gut to at least 88% and reaches highest concentrations in the blood plasma after one to four hours. When in the bloodstream, 60% of the substance are bound to plasma proteins, mostly to albumin. Cenobamate is inactivated mainly by glucuronidation via the enzyme UGT2B7 and to a lesser extent UGT2B4. The enzymes CYP2E1, CYP2A6, CYP2B6, CYP2C19 and CYP3A4 play smaller roles in the drug's metabolism.[14]
Steady state conditions are reached after 14 days. Cenobamate and its metabolites are mostly eliminated via the urine and only to 5.2% via the faeces. The terminal half-life is 50 to 60 hours.[14]
History
The safety and efficacy of cenobamate to treat partial-onset seizures was established in two randomized, double-blind, placebo-controlled studies that enrolled 655 adults. In these studies, patients had partial-onset seizures with or without secondary generalization for an average of approximately 24 years and median seizure frequency of 8.5 seizures per 28 days during an 8-week baseline period. During the trials, doses of 100, 200, and 400 milligrams (mg) daily reduced the number of seizures per 28 days compared with the placebo group.[7]
^ abcd"Ontozry EPAR". European Medicines Agency (EMA). 25 January 2021. Archived from the original on 4 June 2021. Retrieved 4 June 2021. Text was copied from this source which is copyright European Medicines Agency. Reproduction is authorized provided the source is acknowledged.
^ ab"Ontozry: Pending EC decision". European Medicines Agency (EMA). 29 January 2021. Archived from the original on 1 February 2021. Retrieved 1 February 2021. Text was copied from this source which is copyright European Medicines Agency. Reproduction is authorized provided the source is acknowledged.
^"Ontozry". Union Register of medicinal products. Archived from the original on 2 August 2021. Retrieved 3 August 2021.