Anti-Epileptic Medications Flashcards
After a first seizure, what is the risk of having a further seizure?
30-50%
If you have had two seizures, what is the risk of having another seizure?
80%
Why is lamotrigine not used as a first-line anti epileptic?
- Dose needs to be slowly titrated in order to minimise the risk of rashes
- Not as effective as carbamazepine, and is more expensive
However, lamotrigine can be used as monotherapy and is an effective agent for the management of a variety of seizure types
How does carbemazepine affect the OCP?
Carbemazepine is an enzyme-inducing drug which increases the metabolism of oral-contraceptives and thus reduces their effectiveness. Higher dose of contraction and/or other means of contraception is required.
What are two common side effects that may occur when carbemazepine is first commenced?
Sedation and nausea
What is the first-line agent for the management of partial seizures?
Carbemazepine
What is the first-line agent for the management of generalised tonic seizures?
Valproate
What is a potential teratogenic side effect of valproate?
If taken early in pregnancy, valproate increases the risk of neural tube and other birth defects
What type of drug is phenobarbitone?
Barbiturate
Why is phenobarbitone a 3rd or 4th line anti-epileptic agent?
Phenobarbitone is as effective as phenytoin and carbamazepine in partial and generalised tonic-clonic seizures, but its use is limited by initial sedative effects and possible tolerance to its anticonvulsant effects. It also induces the metabolism of a number of other drugs. Because of these efficacy, safety and suitability issues, it is relegated to being 3rd or 4th line.
Does valproate interfere with the OCP?
No, valproate doesn’t interfere with the OCP, but it does carry a higher teratogenic risk than other anti-epileptic drugs
What is the preferred first-line agent for use in status epilepticus?
Phenytoin
Which anti-epileptics increase the risk of OCP failure?
Carbamazepine , phenobarbitone, primidone, topiramate and phenytoin are all enzyme-inducing drugs, increasing the metabolism of oral contraceptives and thus reducing their effectiveness. Pregnancy risk can thus be greatly increased and advice should be given re other contraceptive methods until dose is restabilised. A 3–4 fold increase in the OCP dose may be required to maintain contraceptive efficacy! e.g. up to 100 micrograms/day of ethinyloestradiol (2 high-dose pills per day).
Which anti-epileptic has the least teratogenic effects?
Carbemazepine
Why does the dose of carbemazepine usually have to be titrated up in the majority of patients?
Carbamazepine predictably induces its own metabolism and the dose needs to be gradually increased over 3 to 4 weeks, sometimes 3- to 4-fold simply to maintain the same blood concentrations.
