Treatment for Seizures

Question 1

How and when should antiepileptic drugs be initiated for the management of epilepsy and seizure disorders?

Answer 1

First ever tonic clonic seizure > investigate cause > Perform EEG > if recurrence rate is high or a second seizure has occurred begin treatment:
If its a partial seizure start carbamazepine
if not or uncertain begin sodium valproate
Based on efficacy, the first-line drug for focal (partial) epilepsy is carbamazepine, and for generalised epilepsy is sodium valproate.
For pregnancy as first-line therapy, use levetiracetam

Question 2

Interactions of medications

Answer 2

The most common cause of drug interactions for antiepileptic agents are due to cytochrome P450 (CYP) enzyme and uridine glucuronyl transferases (UGT) mediated enzyme induction and inhibition.
Antidepressants - enzyme inhibition leads to increased serum concentration of of AED
Contraceptives - reduced concentration of AED
Antimicrobials - increased concentration of AED

Question 3

MOA, interactions, precaution of carbamazepine

Answer 3

blocking voltage-dependent and use-dependent sodium channels.
carbamazepine may increase its metabolism; may need to increase dose of oral contraception
Take with food to help prevent stomach upset.
This medicine may cause drowsiness, dizziness or blurred vision especially at the start of treatment or when the dose is increased; if affected, do not drive or operate machinery.
Carbamazepine may also increase the effects of alcohol.
avoid grapefruit juice
Tell your doctor immediately if rash, sore throat, fever, mouth ulcers, bruising or bleeding occur.
Do not stop taking this medicine suddenly

Question 4

MOA, interactions, precaution of sodium valproate.

Answer 4

Other actions include enhancement of GABA, inhibition of glutamate and blockade of T-type calcium channels.

Take with food to reduce stomach upset. Swallow the enteric coated tablets whole; do not crush or chew them.
Valproate may make you feel drowsy; if affected, do not drive or operate machinery. This medicine may also increase the effects of alcohol.
Your appetite may increase when taking this medicine and you may need to pay more attention to your diet to avoid weight gain.
Tell your doctor immediately if symptoms such as fever, rash, abdominal pain, vomiting, jaundice, bruising or bleeding develop.

Question 5

Define Status epilepticus

Answer 5

Status epilepticus is defined as five or more minutes of either continuous seizure activity or repetitive seizures without regaining consciousness

Question 6

Treating status epilepticus

Answer 6

Step 1: After 5 minutes of continuous seizure activity
when the patient has repeated seizures without full recovery of consciousness between attacks. Give benzodiazepine
Step 2: Give an antiepileptic drug, phenytoin or sodium valproate is first-line treatment. However, phenytoin has more adverse effects (eg arrhythmias, infusion problems, hypotension
Step 3: If the seizure continues (refractory status epilepticus), transfer the patient to the intensive care unit and seek expert advice.

Question 7

Side effects of AED

Answer 7

Osteoporosis
Antiepileptic medicines (especially those that induce CYP450) increase the metabolism of vitamin D (leading to decrease calcium absorption) which has cascading effects of secondary hyperparathyroidism, increased bone resorption and accelerated bone loss
Skin reactions
severe cutaneous adverse reactions (SCAR). SCARs include Stevens-Johnson syndrome (SJS), Toxic epidermal necrolysis (TENs) and Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. They are epidermal and mucosal necrosis. TEN is more severe than SJS.
The most common antiepileptics known to cause these reactions are carbamazepine, lamotrigine and phenytoin

Question 8

How does phenytoin toxicity happen

Answer 8

Phenytoin toxicity
Phenytoin has a narrow therapeutic window hence a fine balance must be found between efficacy and dose-related side effects.
Since phenytoin is highly protein-bound and free (unbound) phenytoin is the component producing the pharmacological effect, any factor which changes the protein binding of phenytoin would be expected to alter the free drug levels. Thereby interactions can lead to toxicity.
even a small change in dose can lead to a large change in phenytoin levels.