Anti Epileptics Flashcards Preview

Sem 5 Pharm > Anti Epileptics > Flashcards

Flashcards in Anti Epileptics Deck (23):
1

Name 3 short term treatment options for acute epilepsy

Lorazepam
Diazepam
Phenytoin

2

Name two drug classes used in the long term management of epilepsy

Voltage gated sodium channel blockers
Drugs that enhance GABA mediated inhibition

3

Name 3 examples of voltage gated sodium channel blockers

Carbamazepine
Phenytoin
Lamotrigine

4

Name 2 examples of drugs that enhance GABA mediated inhibition

Valproate
Benzodiazepines

5

What is the mechanism of action of VGSCB

Bind to channel on inside of membrane (can only get in during depolarisation), leaves channel in inactivated state, therefore firing frequency decreases
They increase inactivation state
This prevents propagation of the impulse

6

What caution do you need to be wary of in carbamazepine and phenytoin?

Both induce CYP450, therefore increases metabolism of common drugs such as warfarin, COCP, corticosteroids, phenytoin, carbamazepine.
Therefore their plasma concentration decreases. (Incl itself).

7

What do you need to wary of phenytoin regarding its pharmacokinetics?

It does not follow linear PKs when at therapeutic levels (it does when sub therapeutic).

8

What type of seizures can phenytoin and carbamazepine be useful for?

Generalised tonic clonic, all partial.
Not good for absent.

9

What monitoring is needed for most anti epileptic drugs?

Regular bloods- measuring free plasma conc (toxicity etc), bone profile

10

Name 4 side effects of carbamazepine + phenytoin

Ataxia, drowsiness, dizziness
Variation in BP
N + V, rash, hyponatraemia

Gingival hyperplasia (phenytoin only)

11

What is the rare, severe side effect of carbamazepine

Severe bone marrow suppression, resulting in neutropenia

12

What drug is contraindicated for phenytoin and why?

Cimetidine
Increases plasma conc of phenytoin

13

Name 4 benefits of Lamotrigine over other drugs?

Fewer ADRs,
Rash, dizzy, ataxia, somnolence, nausea
Also safer in pregnancy
Also useful in absent seizures too
No induction of CYP450, therefore fewer DDIs

14

What is the mechanism of action of benzodiazepines?

Bind to their own site in GABA receptor.
Leads to increase of Cl- into the neurone, thus increasing the threshold for an action potential.

Positive allosteric effect, meaning when either one is bound, increases each others binding.

15

What PKs do benzodiazepams follow?

Linear

16

ADRs of benzodiazepines

Sedation, tolerance, aggression, confusion, impaired coordination, dependence, withdrawal, resp and CNS depression when stopped abruptly.

17

What can be used to reverse a benzodiazepines overdose/simply reverse effects?

IV Flumazenil 300-600mcg.

18

What are benzodiazepines used for in epilepsy?

Status epilepticus (Lorazepam, diazepam)
Abscence, short term use (clonazepam)

19

What is the mechanism of action of valproate (in brief)

VGSCB, Ca2+ blocker, inhibition of GABA inactivating enzymes, stimuli of GABA synthesising enzymes (therefore more GABA)

20

List 4 ADRs of valproate

Sedation, ataxia, tremor, weight gain, increase in transaminase LFTs
Rarely- liver failure

21

List 3 main DDIs of valproate

Antidepressants typically inhibit action of valproate
Antipsychotics typically antagonise valproate as they lower convulsive threshold
Aspirin increases plasma conc of valproate due to competitive binding.

22

How do you need to monitor valproate?

Plasma conc is not closely associated with efficacy
Therefore need to monitor for blood, metabolic and hepatic disorder

23

What is the difference between benzodiazepines and barbiturates, regarding mechanism of action?

Benzodiazepines- increase frequency of Cl- channels
Barbiturates- increase duration of Cl- channel opening