Workshop 2: Management of epilepsy Flashcards
What are 1st/2nd/ 3rd line for epilepsy?
1st line – Carbamazepine, sodium valproate, lamotrigine and topiramate
2nd line – levetiracetam, oxcarbazepine, clobazam
3rd line – phenobarbital, phenytoin
What is the mechanism of action of carbamazapine?
Blocks sodium channels
What is the mechanism of action of sodium valpraote?
- Causes an increase in GABA
- Weak inhibitor of GABA transaminase
- Inhibits Na channels – but less than phenytoin
- Inhibits T type calcium channels
What is the mechanism of action of lamotrigine?
Blocks Na channel
What is the mechanism of action of topiramate?
- Blocking sodium and calcium channels
- Enhancing the action of GABA
- Blocking AMPA receptors and
- Weakly inhibiting carbonic anhydrase
What is the mechansim Levetiracetam?
- Blocking sodium and calcium channels
- Enhancing the action of GABA
- Blocking AMPA receptors
- Weakly inhibiting carbonic anhydrase
What is the mechanism if action of Clobazam?
Enhances GABA activity by increasing the frequency of the opening of GABAa receptors, so has an enhanced inhibitory effect
Name the benzodiazepenes?
Temazepam, clonazepam, midazolam, diazepam, clobazam
What are the key questions you should ask people prescribed AED as part of your clinical check to indentify how well their epilepsy is controlled and any associated risks? Where would you document it?
- How often they have seizures
- Make sure the patient is kept on the same brand
- Check side effects, may need to change treatment plan
- Lifestyle advice
- Drug interactions - check other meds patients are own
- Pregnancy
Document on PMR or patient notes in hospital
How do enzyme inducing drugs affect contraceptive drugs? Name enzyme inducing drugs and non enzyme inducing drugs
Enzyme inducing drugs increase the activity of enzymes in the liver responsible for metabolising and excreting drugs - this results in decreased blood levels of the drug - so can make certain birth controls less effective and increase the risk of unplanned pregnancy by 3x
Enzyme inducing AED include carbamazepine, lamotrigine oxcarbazepine, phenytoin, phenobarbitone, sodium valproate.
Non enzyme inducing AED include: acetazolamie, clobazam, ethosuximide, gabapentin
What drugs are the safest to use in pregnancy?
Lamotrigine and levetiracetam
What should you do if you are on sodium valrproate and fall pregnant?
Do not stop taking sodium valproate. Seizures could cause more harm for you and your unborn baby than any risks associated with the drugs themselves.
Why is uncontrolled switching of AED a problem?
Switching from one drug to another may mean that higher, or lower amounts of active ingredients may reach the brain – this could cause a seizure
What are the different switching categories and which AEDs belong to each category?
Category 1 – phenytoin, carbamazepine, phenobarbital, primidone
For these drugs, doctors are advised to ensure that their patient is maintained on a specific manufacturer’s product
Category 2 – valproate, lamotrigine, perampanel, retigabine, rufinamide, clobazam, clonazepam, oxcarbazepine, eslicarbazepine, zonisamide, topiramate
For these drugs, the need for continued supply of a particular manufacturer’s product should be based on clinical judgement and consultation with patient and/or carer, taking into account factors such as seizure frequency and treatment history
Category 3 - levetiracetam, lacosamide, tiagabine, gabapentin, pregabalin, ethosuximide, vigabatrin
For these drugs, it is usually unnecessary to ensure that patients are maintained on a specific manufacturer’s product unless there are specific reasons such as patient anxiety and risk of confusion or dosing errors
What causes drug resistance in epilepsy?
- An increased number of p-glycoprotein type pumps at the BBB
- Haplo insufficiency of the glucose transporter GLUT1
- Cause unknown but current drugs target similar mechinsims
