Drug Safety Update
November 2007: Herbal ingredient St John's Wort may interact with antiepileptics and should not be taken concurrently.
April 2008: Carbamazepine has a higher risk of Stevens -Johnson syndrome in some Asian populations: genetic testing is recommended - see also Dec 2012 update below
August 2008: Antiepileptics risk of suicidal thoughts and behaviour
April 2009: Antiepileptics adverse effects on bone (carbamazepine, phenytoin, primidone and sodium valproate)
December 2012: Carbamazepine, oxcarbazepine and eslicarbazepine potential risk of serious skin reactions
November 2016: Patient Safety Alert: Risk of death or severe harm from error with injectable phenytoin
October 2017: Gabapentin: risk of severe respiratory depression even without concomitant opioid medicines.
November 2017: Antiepileptics updated advice on switching between different manufacturers products
September 2018: Valproate Pregnancy Prevention Programme: actions required now from GPs, specialists, and dispensers
December 2018:Valproate medicines: are you acting in compliance with the pregnancy prevention measures?
April 2018 and May 2018 and Dec 18: Valproate medicines must no longer be used in women and girls of childbearing potential unless a Pregnancy Prevention Programme is in place. All prescribers that are initiating valproate should complete the Risk Acknowledgement Form and keep a copy in the patient's healthcare records as a permanent record of your discussion.
Caution with topiramate in women of child-bearing potential or pregnancy - risk of fetal malformations and can impair the effectiveness of hormonal contraceptives (see BNF).
March 2019: Medicines with teratogenic potential: what is effective contraception and how often is pregnancy testing needed?
April 2019: Valproate medicines and serious harms in pregnancy: new Annual Risk Acknowledgement Form and clinical guidance from professional bodies to support compliance with the Pregnancy Prevention Programme
April 2019: Pregabalin (Lyrica), gabapentin (Neurontin) and risk of abuse and dependence: new scheduling requirements from 1 April
February 2020: Valproate (Epilim▼, Depakote▼) pregnancy prevention programme: updated educational materials
CG 137 Epilepsies: diagnosis and management, updated April 2018
Drug Level Monitoring is useful for both checking compliance and for checking therapeutic levels particularly for phenytoin.
Drug Interactions are common between antiepileptics and other drugs particularly those which are hepatically metabolised. Interactions should be checked when prescribing a new drug for patients on antiepileptics.
It is important to avoid switching brands for some anti-epileptics - see BNF.
Neuropathic pain may be treated using antiepileptics particularly gabapentin and pregabalin. See local guidelines.
- has a narrow therapeutic index and the relationship between the dose and plasma concentration is non-linear. Dose adjustments should be made in small increments of 25mg if the level is near the end of the therapeutic range (eg for dose increases above 300mg daily)
- 90 mg of phenytoin (chewable tablets or suspension) is equivalent to 100mg of phenytoin sodium (capsules or tablets) so care is needed if transferring from one formulation to another.
- IV phenytoin the dosage should be divided and given 8 hourly rather than once daily to avoid toxic levels developing.
- should not be used in females with child bearing potential unless a pregnancy prevention programme is in place and a Risk Acknowledgement Form is completed
- within its licensed indications is for restricted use for refractory patients who remain uncontrolled with or are intolerant to other adjunctive anti-epileptic medicines. Levetiracetam should be tried as an option prior to prescribing brivaracetam
- is available for the adjunctive treatment of focal seizures. An overview of the evidence supporting the use of perampanel is available on the NICE website .
- when used in palliative care levetiracetam may be given as a subcutaneous injection. (unlicensed route of administration)