Paeds · neurology-neurodisability-and-neuromuscular
Antiseizure medicines: selection, adverse effects and monitoring
Also known as antiseizure medication · antiepileptic drug · ASM selection · antiepileptic drug monitoring · anticonvulsant adverse effects · antiepileptic pharmacology · valproate pregnancy prevention programme
A fellowship approach to antiseizure medicines in children: selecting the syndrome-matched first-choice drug, anticipating and monitoring the adverse effects that determine whether a child stays on treatment, and applying the valproate pregnancy prevention programme, the lamotrigine slow-titration rule, and the carbamazepine-worsens-absence contraindication.
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Red flags
- Never give carbamazepine, oxcarbazepine, phenytoin or gabapentin to a child with absence or myoclonic epilepsy — they worsen both and can precipitate absence status epilepticus
- A rash within the first eight weeks of lamotrigine, carbamazepine or phenytoin is Stevens-Johnson syndrome or toxic epidermal necrolysis until proven otherwise — stop the drug immediately and do not rechallenge
- Valproate is contraindicated in girls and women of childbearing potential unless every condition of the MHRA pregnancy prevention programme is met — the teratogenic and neurodevelopmental risk is dose-dependent and substantial
- Valproate hepatotoxicity is highest in children under two years on polytherapy with a developmental delay — check liver function early and counsel families about the warning signs of vomiting, lethargy and jaundice
- A child on carbamazepine or oxcarbazepine who develops lethargy, headache or a seizure may have hyponatraemia from drug-induced SIADH — check the serum sodium before increasing the dose
- Vigabatrin causes irreversible visual field constriction that may only declare on perimetry years later — baseline and periodic visual field testing is mandatory and informed consent is required
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- Neurology - recognise and investigate common seizure disorders and epilepsies
- Clinical pharmacology - antiseizure medicine selection, adverse effects and monitoring
- Growth and Development
- Neurology - antiseizure medicine selection by syndrome and the valproate pregnancy prevention programme
- Acquired and genetic neurological disease - adverse effects of antiseizure medicines and therapeutic drug monitoring
- Renewed curriculum for first-year trainees from 2027 - Learning goal 6: Clinical management - essential general paediatrics
- Neurology 10-12
- Pharmacology and toxicology 10-12
- Clinical Applications
- Long Cases
- Short Cases
- 9. Neurology - epilepsy and paroxysmal disorders
- 10. Pharmacology - safe prescribing and therapeutic drug monitoring
- 4. Professional skills and knowledge: Patient management
- Foundation of Practice (FOP)
- Theory and Science (TAS)
- Applied Knowledge in Practice (AKP)
- Clinical
- History
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- General Pediatrics Content Outline - D16 Neurology (6%)
- General Pediatrics Content Outline - Universal Task 4: Management and Treatment
- General Pediatrics Content Outline - Universal Task 3: Pharmacology
- Patient Care 4: Clinical Reasoning
- Patient Care 5: Patient Management
- Medical Knowledge 1: Pharmacology and therapeutics
- Systems-Based Practice 2: Coordinated chronic disease care
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- Pediatrics: Foundations EPA #8 - Communicating assessment findings and management plans to patients and families
- Pediatrics: Neurology applied domain
A ten-year-old boy with newly diagnosed focal epilepsy is started on levetiracetam and develops irritability and aggression within two weeks; the task is to recognise the behavioural adverse effect, weigh it against seizure control, and decide whether to reduce, switch, or add a second agent. A fourteen-year-old girl with juvenile myoclonic epilepsy needs valproate for optimal seizure control, but the valproate pregnancy prevention programme applies, and the choice of an alternative such as levetiracetam or lamotrigine must be framed around her reproductive future. A seven-year-old on lamotrigine develops a rash six weeks into treatment, and the decision to stop or push through is the one that separates Stevens-Johnson syndrome from a benign morbilliform eruption. [5] [7] [11]
Select the drug by the syndrome — never carbamazepine or phenytoin for absence or myoclonus, never valproate first in a girl of childbearing potential. Start slow — titrate every one to two weeks, because the common severe adverse effects are dose-rate-dependent: lamotrigine rash, valproate hepatotoxicity, topiramate cognitive blunting. Survey the adverse effects actively — ask about behaviour on levetiracetam, weigh the child on valproate and topiramate, check the sodium on carbamazepine. Switch after the first failed monotherapy, not before — two appropriately chosen and tolerated drugs failing defines drug-resistant epilepsy and triggers a presurgical referral. Stop the drug immediately if a severe cutaneous, hepatic, or haematological reaction appears, and never rechallenge. [1] [4] [5]
Overview & Definition
Antiseizure medicines are the drugs that suppress epileptic seizures by modulating the electrical activity of neurons, and their use in children is governed by the principle that the drug is chosen for the epilepsy syndrome, not for the seizure alone. The older term antiepileptic drug is being replaced by antiseizure medicine because these drugs suppress seizures without curing the underlying epilepsy, and the newer term is the one used in the ILAE and NICE guidelines. [1] [9]
The fellowship framing rests on one distinction that governs selection. A narrow-spectrum drug controls focal seizures but worsens generalised seizures such as absence and myoclonus, while a broad-spectrum drug controls both. Carbamazepine, oxcarbazepine, phenytoin, gabapentin and pregabalin are narrow-spectrum, and they are the drugs that worsen absence and myoclonic epilepsy. Valproate, levetiracetam, lamotrigine, topiramate, zonisamide and the benzodiazepines are broad-spectrum. The selection move is to classify the syndrome from the EEG before the prescription, because the wrong spectrum drug does not merely fail but actively worsens the epilepsy. [1] [5]
The clinical importance of this topic is that adverse effects, not lack of efficacy, are the commonest reason children stop an antiseizure medicine. Roughly one in three children discontinues a drug because of an adverse effect, and the quality of life of a child with well-controlled seizures is driven more by the cognitive, behavioural and systemic effects of the medicine than by the seizure count. The fellowship skill is to anticipate these effects, to monitor for them, and to adjust the treatment so that the child is both seizure-free and functioning at their best. [5] [6]
References12ShowHide
- [1]Glauser T, Ben-Menachem E, Bourgeois B, et al. Updated ILAE evidence review of antiepileptic drug efficacy and effectiveness as initial monotherapy for epileptic seizures and syndromes. Epilepsia, 2013.PMID 23350722
- [2]Marson AG, Appleton R, Baker GA, Chadwick DW, Doughty J, Eaton B, Gamble C, Jacoby A, Shackley P, Smith DF, Tudur-Smith C, Vanoli A, Williamson PR. A randomised controlled trial examining the longer-term outcomes of standard versus new antiepileptic drugs. The SANAD trial. Health Technol Assess, 2007.PMID 17903391
- [3]Marson A, Burnside G, Appleton R, et al. The SANAD II study of the effectiveness and cost-effectiveness of levetiracetam, zonisamide, or lamotrigine for newly diagnosed focal epilepsy: an open-label, non-inferiority, multicentre, phase 4, randomised controlled trial. Lancet, 2021.PMID 33838757
- [4]Kwan P, Arzimanoglou A, Berg AT, et al. Definition of drug resistant epilepsy: consensus proposal by the ad hoc Task Force of the ILAE Commission on Therapeutic Strategies. Epilepsia, 2010.PMID 19889013
- [5]Perucca P, Gilliam FG. Adverse effects of antiepileptic drugs. Lancet Neurol, 2012.PMID 22832500
- [6]Loring DW, Meador KJ. Cognitive side effects of antiepileptic drugs in children. Neurology, 2004.PMID 15037684
- [7]Pack AM, Oskoui M, Williams Roberson S, Donley DK, French J, Gerard EE, Gloss D, Miller WR, Munger Clary HM, Osmundson SS, McFadden B, Parratt K, Pennell PB, Saade G, Smith DB, Sullivan K, Thomas SV, Tomson T, Dolan O'Brien M, Botchway-Doe K, Silsbee HM, Keezer MR. Teratogenesis, Perinatal, and Neurodevelopmental Outcomes After In Utero Exposure to Antiseizure Medication: Practice Guideline From the AAN, AES, and SMFM. Neurology, 2024.PMID 38748979
- [8]Vidaurre J, Gedela S, Yarosz S. Antiepileptic Drugs and Liver Disease. Pediatr Neurol, 2017.PMID 29097018
- [9]Jones KEA, Howells R, Mallick AA, Paul SP, Dey I. NICE guideline review: Epilepsies in children, young people and adults NG217. Arch Dis Child Educ Pract Ed, 2023.PMID 37339862
- [10]French JA, Lawson JA, Yapici Z, Ikeda H, Polster T, Nabbout R, Curatolo P, de Vries PJ, Dlugos DJ, Berkowitz N, Voi M, Peyrard S, Pelov D, Franz DN. Adjunctive everolimus therapy for treatment-resistant focal-onset seizures associated with tuberous sclerosis (EXIST-3): a phase 3, randomised, double-blind, placebo-controlled study. Lancet, 2016.PMID 27613521
- [11]Guberman AH, Besag FM, Brodie MJ, Dooley JM, Duchowny MS, Pellock JM, Richens A, Stern RS, Trevathan E. Lamotrigine-associated rash: risk/benefit considerations in adults and children. Epilepsia, 1999.PMID 10403224
- [12]Shellhaas RA, Joshi SM. Vitamin D and bone health among children with epilepsy. Pediatr Neurol, 2010.PMID 20472188