Ethosuximide


  Issues for Surgery


Precipitation of rebound seizures or status epilepticus if omitted.


  Advice in the Perioperative period


Elective and Emergency Surgery

Continue.

Patients should be advised to take their regular medications on the day of surgery1, 2, 3.

Abrupt withdrawal of any anticonvulsant drug should be avoided1.

Confirm with the patient if they need to be maintained on a specific manufacturer’s product (see Further Information).

Post-operative Advice

Regular dosing of the patient’s usual oral medication should be re-established as early as possible post-operatively2, 3.

Ethosuximide is only available as oral preparations. If patients cannot resume their usual oral medication post-operatively, the advice of a Neurologist should be sought to determine the most appropriate antiepileptic preparation, dose, route and frequency to be used.

Monitor renal function.


  Interaction(s) with Common Anaesthetic Agents


None1, 4, 5, 6.

For general information regarding the use of anaesthetic agents in epilepsy patients – see Antiepileptics – A General Overview.


  Interaction(s) with other Common Medicines used in the Perioperative Period


For general information regarding the use of antiemetics in epilepsy patients – see Antiepileptics – A General Overview.

Antimicrobials

Concomitant use of ethosuximide with the following can increase the risk of myelosuppression1: -

  • co-trimoxazole
  • linezolid
  • trimethoprim

Whilst single surgical prophylactic doses should not pose a problem, continued post-operative treatment may require close monitoring. Consult current product literature.


  Further Information


MHRA/CHM Advice: Antiepileptic Drugs: updated advice on switching between different manufacturer’s products for a particular drug (November 2017)1

Ethosuximide is a category 3 antiepileptic, hence it is usually unnecessary to ensure that patients are maintained on a specific manufacturer’s product as therapeutic equivalence can be assumed. However, other factors are important when considering if switching is appropriate such as patient anxiety, risk of confusion or dosing errors. (For more information see ‘Antiepileptics – A General Overview).

Blood Dyscrasias

Blood dyscrasias (leucopenia, agranulocytosis, aplastic anaemia and pancytopenia) have been reported with use of ethosuxmide6. Patients should be monitored for sign of blood disorders (e.g. fever, mouth ulcers, bruising, or bleeding)1. Withdrawal of the drug may be necessary and the patient’s Neurologist should be consulted to ensure an appropriate management plan.

 

  References


  1. Joint Formulary Committee. British National Formulary (online) London: BMJ Group and Pharmaceutical Press http://www.medicinescomplete.com [Accessed 3rd July 2019]
  2. Perks A, Cheema S, Mohanraj R. Anaesthesia and epilepsyBJA: British Journal of Anaesthesia. 2012; 108(4):562-571
  3. Carter EL, Adapa RM. Adult epilepsy and anaesthesia. BJA Education. 2015; 15(3):111-117
  4. Baxter K, Preston CL (eds), Stockley’s Drug Interactions (online) London: Pharmaceutical Press. http://www.medicinescomplete.com [Accessed on 30th June 2019]
  5. Ethosuximide. In: Brayfield A (Ed), Martindale: The Complete Drug Reference. London: The Royal Pharmaceutical Society of Great Britain. http://www.medicinescomplete.com [Accessed 3rd July 2019]
  6. Summary of Product Characteristics – Ethosuximide Essential Generics 250mg/5ml Syrup. Essential Pharma Ltd. Accessed via www.medicines.org.uk 03/07/2019 [date of revision of the text April 2019]