Flashcards in Anti Epileptics Deck (23):
Name 3 short term treatment options for acute epilepsy
Name two drug classes used in the long term management of epilepsy
Voltage gated sodium channel blockers
Drugs that enhance GABA mediated inhibition
Name 3 examples of voltage gated sodium channel blockers
Name 2 examples of drugs that enhance GABA mediated inhibition
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
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).
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).
What type of seizures can phenytoin and carbamazepine be useful for?
Generalised tonic clonic, all partial.
Not good for absent.
What monitoring is needed for most anti epileptic drugs?
Regular bloods- measuring free plasma conc (toxicity etc), bone profile
Name 4 side effects of carbamazepine + phenytoin
Ataxia, drowsiness, dizziness
Variation in BP
N + V, rash, hyponatraemia
Gingival hyperplasia (phenytoin only)
What is the rare, severe side effect of carbamazepine
Severe bone marrow suppression, resulting in neutropenia
What drug is contraindicated for phenytoin and why?
Increases plasma conc of phenytoin
Name 4 benefits of Lamotrigine over other drugs?
Rash, dizzy, ataxia, somnolence, nausea
Also safer in pregnancy
Also useful in absent seizures too
No induction of CYP450, therefore fewer DDIs
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.
What PKs do benzodiazepams follow?
ADRs of benzodiazepines
Sedation, tolerance, aggression, confusion, impaired coordination, dependence, withdrawal, resp and CNS depression when stopped abruptly.
What can be used to reverse a benzodiazepines overdose/simply reverse effects?
IV Flumazenil 300-600mcg.
What are benzodiazepines used for in epilepsy?
Status epilepticus (Lorazepam, diazepam)
Abscence, short term use (clonazepam)
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)
List 4 ADRs of valproate
Sedation, ataxia, tremor, weight gain, increase in transaminase LFTs
Rarely- liver failure
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.
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