Anti Epileptic Drugs

1. When to Start Anti-Epileptic Drug (AED)?

Start after:

  • ≥2 unprovoked seizures
  • 1 seizure + abnormal MRI/EEG
  • Focal structural lesion
  • High recurrence risk

Do NOT start after:

  • Single provoked seizure (e.g., alcohol withdrawal)


2. Principles of AED Therapy

Golden Rules

✔ Start monotherapy
✔ Start low, go slow
✔ Choose based on seizure type
✔ Avoid enzyme inducers when possible
✔ Consider comorbidities
✔ Review driving eligibility
✔ Counsel regarding SUDEP


3. First-Line Drug Selection (UK/NICE )

Seizure Type

First Line

Alternatives

Focal

Lamotrigine

Levetiracetam, Carbamazepine

Generalised tonic-clonic

Valproate (if male)

Lamotrigine

Absence

Ethosuximide

Valproate

Myoclonic

Valproate

Levetiracetam

Women of childbearing age

Avoid valproate



4. Core Anti-Epileptic Drugs Table

Drug

Mechanism

Major Side Effects

Valproate

↑ GABA, Na block

Weight gain, tremor, hepatotoxicity

Avoid in pregnancy

Lamotrigine

Na channel block

Stevens–Johnson syndrome

Levetiracetam

SV2A modulation

Irritability

Carbamazepine

Na channel block

Hyponatraemia,Worsens absence seizure,Enzyme inducer

Oxcarbazepine

Na channel block

Hyponatraemia

Ethosuximide

T-type Ca block

GI upset

Topiramate

Na block, GABA ↑

Cognitive slowing,Renal stones,Weight loss

Phenytoin

Na channel block

Gingival hyperplasia,Non-linear kinetics

Lacosamide

Slow Na inactivation

PR prolongation

Clobazam

GABA-A

Sedation,Tolerance

Perampanel

AMPA antagonist

Aggression


  • Carbamazepine worsens absence/myoclonic seizures
  • Valproate contraindicated in women of childbearing age
  • Phenytoin has zero-order kinetics
  • Enzyme inducers reduce OCP efficacy

 5.Monitoring Table for Anti-Seizure Drugs

Drug

Tests

Valproate

LFT, INR, FBC, platelets

Baseline → 2–4 weeks → every 3–6 months in first year

Carbamazepine

FBC, LFT, U&E (Na)

2–4 weeks → 3 months → annually

Lamotrigine

LFT (baseline), FBC,Clinical rash monitoring (no routine labs usually)

Levetiracetam

Renal function

Phenytoin

LFT, FBC, U&E, albumin

Topiramate

U&E, bicarbonate-Periodic

Oxcarbazepine

U&E (Na), LFT,2–4 weeks → periodic

Gabapentin

Renal function-Periodic in CKD

Pregabalin

Renal function-Periodic in CKD


6.Renal vs Hepatic Adjustment

Drug

Renal Adjustment

Hepatic Adjustment

Valproate

No major

Avoid severe liver disease

Lamotrigine

Minor

Reduce in hepatic impairment

Levetiracetam

YES

No major

Carbamazepine

No

YES

Phenytoin

No

YES

Topiramate

YES

Caution

Lacosamide

YES

Caution

Gabapentin

YES

No


7. Special Situations

Pregnancy

Avoid:

  • Valproate (neural tube defects)
  • Topiramate (cleft lip)

Preferred:

  • Lamotrigine
  • Levetiracetam

Folic acid 5 mg preconception.



8.When Is Epilepsy Drug-Resistant?

Failure of:

  • 2 appropriate AEDs at adequate dose

Then refer for:

  • Epilepsy surgery
  • Vagus nerve stimulation
  • Ketogenic diet


9. Epilepsy Surgery

Indicated in:

  • Drug-resistant focal epilepsy
  • Mesial temporal sclerosis

Procedures:

  • Temporal lobectomy
  • Laser ablation


10. Non-Pharmacological Management

  • Sleep hygiene
  • Avoid alcohol
  • Stress reduction
  • Driving restrictions (UK: 1 year seizure-free)


11. SUDEP (Sudden Unexpected Death in Epilepsy)

Risk factors:

  • Poor control
  • Nocturnal seizures
  • Non-compliance

Always counsel patients.


12. Drug Withdrawal

Consider if:

  • Seizure-free 2–5 years
  • Normal EEG
  • No structural lesion

Taper slowly over months.