Week 12 - Anti-epileptic drugs Flashcards

1
Q

What are Seizures characterised by? what is their casue?

A

Excessive asynchronous excitation of a population of cortical neurons

No obvious cause but can be associated an initiating factor like brain tumour, head trauma, drug use, etc

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2
Q

What does a seizure look like in an EEG?

A
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3
Q

What is epilepsy?

A

diagnosed if someone has experienced at least two unprovoked seizures occurring more than 24 hours apart

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4
Q

How can you categorise seziures?

A

Focal onset or Generalised onset

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5
Q

How is a focal onset categorised and what occurs in this?

A

Aware:
- remains conscious
- altered senses
- generally remembers

Impaired awareness:
- loss of consciousness & recall

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6
Q

How is generalised onset categorised and what occurs in this?

A

Motor:
- tonic-clonic
- tonic
- myoclonic
- muscle stiffness alternating with spasms

Non-motor:
- absence

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7
Q

What are aims of anti-epileptic drug therapy?

A

prevent seizures by disrupting neuronal membrane excitability -> block Na+ and Ca2+ channels

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8
Q

What are 3 places to target to enhance GABA neurotransmission?

A

Target the:
- enzyme GABA transaminase (breaks down GABA in pre-syn neuron)
- GAT-1 transporter
- GABAa receptor

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9
Q

What are GABA transaminase inhibitors and how do they work? eg?

A

GABA transaminase inhibition -> less breakdown of GABA in pre-synaptic neuron -> increase intracellular releasable stores of GABA

Eg:
Valproate
Vigabatrin

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10
Q

What are GAT inhibitors and how do they work? eg?

A

GABA is taken up back into (reuptake) the pre-synaptic neuron by GAT

GAT inhibition -> increased extra-neuronal GABA bc less GABA undergoes reuptake

Eg:
Tiagabine

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11
Q

What are GABAa receptor modulators and how do they work? eg?

A

Endogenous GABA activates GABAa receptor
Benzodiazepines bind allosterically to BDZ receptor site (diff from active site) -> enhances GABA action

Eg:
Benzodiazepines

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12
Q

What is Status Epilepticus?

A

= continuous seizure activity or repeated seizures w no recovery of consciousness between seizures

duration needs to be at least 30 mins to diagnose

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13
Q

Action potential visualised

A
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14
Q

What states do Na+ channels exist in?

A
  • Resting
  • Open
  • Inactivated
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15
Q

What happens to neurons during seizures?

A

fire at a high freq -> depolarisation shifts equilibrium towards to inactivated state

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16
Q

What are Na+ channel blockers and how do they work? eg?

A

Channel blockers prefer inactivated state -> more depol = more neurons in inactivated state -> channel blockers work more

Eg:
Carbamazepine
Lamotrigine
Phenytoin

17
Q

What are Ca2+ channel blockers and how do they work? What are the types? eg?

A

High Voltage Associated:
- Ca2+ channels strongly associated w partial seizures
- blockers inhibit excitatory neurotransmitter release
- Eg -> Gabapentin

T-Type:
- T-type Ca2+ channels located in thalamus
- associated w absence seizures
- Eg -> Ethosuximide

18
Q

What is first line anti-epileptic drug? for focal and generalised

A
19
Q

Are anti-epileptic drugs fine for pregnancy?

A

NO all are bad especially valproate

20
Q

What are some unwanted effects of Anti-epileptic drugs?

A

Sedation
Weight gain
Cosmetic changes - hair growth, gums are bigger, etc
Skin rashes