Epilepsy + Anti Epileptic Drugs Flashcards by Emily Stephens

What is the key excitatory neurotransmitter?
What receptor in involved?

Glutamate
NMDA receptor

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What is the key inhibitor neurotransmitter?
What receptor in involved?

GABA
Via GABA_A/B receptors

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What is a seizure?

Clinical manifestation of abnormal excessive excitation + synchronisation of a group of neurones within the brain

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What determines how a seizure presents?

Where uncontrolled signalling occurs (can be anywhere in brain)

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What is an epileptic seizure?

A transient occurrence of signs and/or symptoms due to abnormal excessive or synchoronous neuronal activity in the brain

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What is epilepsy?

A disorder of the brain characterised by a predisposition to generate epileptic seizures unprovoked by a systemic or neurological insult

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Risk factors of epilepsy

premature birth
complicated febrile seizure
head trauma, infection or tumour
cerebrovascular disease
dementia + neurodegenerative disorders

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Define prodrome

Early signs or symptoms a seizure may be coming hours to days before

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What does the term ictal mean?

During a seizure

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What does the term interictal mean?

Between seizures

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What does the term post ictal mean?

After seizure subsides

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What class of drug is carbamazepine?

Sodium channel blocker

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What are uses of carbamazepine?

Epilepsy
Trigeminal neuralgia

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What is the mechanism of action of carbamazepine?

Sodium channel blocker
- blocks VGNC in excitatory neurone
- reduces Ca2+ influx + glutamate release

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what are adverse drug reactions of carbamazepine?

dizziness
skin ash
eosinophilia
leukopenia
hyponatraemia

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What are important drug drug interactions of carbamazepine?

reduces COCP effect
increases warfarin metabolism
CYP3A4 inhibitors e.g.clarithryomycin + diltiazem increase [carbamazeipine]

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Why should carbamazepine not been given during pregnancy?

Teratogenic
- Neural tube defects
- Bone marrow depression
- AV conduction issues

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What is the mechanism of action of phenytoin?

Sodium channel blocker
- blocks VGNC in excitatory neurone
- reduces Ca2+ influx + glutamate

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What are adverse drug reactions of phenytoin?

dizziness
skin rash
visual disturbances
arrhythmia
gingival hyperplasia

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What is gingival hyperplasia?

Overgrowth of gums

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Classifications of sezuires

Focal onset
Generalised onset
Unknown onset

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What is a tonic clonic seizure?

Typical epileptic fit
- tonic stage: loss of consciousness, stiff body
- clonic stage: limbs jerk, possible loss of bladder/bowel control

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What is an absence seizure?

Loss of awareness of surroundings
- staring blankly into space
- looks like daydreaming
- slight jerking of body
- unable to remember them

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What is a clonic seizure?

Body shakes + jerks but does not go stiff at start

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What is a tonic seizure?

Body muscles become stiff

What is a atonic seizure?

All muscles suddenly relax

What class of drug is sodium valproate?

Anticonvulsant

Uses of sodium valproate

Most types of epilepsy

What is the mechanism of action for sodium valproate?

Increases GABA synthesis + transcription of channel coding genes

What are adverse drug reactions of sodium valproate?

- hepatotoxicity - appetite stimulant - alopecia - thrombocytopenia

What are contraindications of sodium valproate?

**teratogentic** - Avoided where pregnancy is possible - Unless pregnancy prevention programme is in place

What are important drug drug interactions for sodium valproate?

Increases [lamotrigine] + [phenytoin] > decreases their action by displacing them off blood proteins

Outline the prescription of sodium valproate

No one under 55 will be newly prescribed unless two specialists agree there is no other effective or tolerated treatment, or there are reasons that the reproductive risk doesnt apply

Describe the pregnancy prevention programme

At least one highly effective contraceptive method OR Two complimentary forms including barrier

What class of drug is lamotrigine?

Na+ and Ca2+ channel blocker

What are the uses of lamotrigine?

Focal seizures Generalised tonic clonic seizures

What is the mechanism of action of lamotrigine?

**Na+ and Ca2+ channel blocker** - less enters excitatory neurone > less glutamate released to post synaptic neurone

What are adverse drug reactions of lamotrigine?

Aggression Agitation Hypersensitivity

What are important drug drug interactions of lamotrigine?

Sodium valproate + phenytoin increases [lamotrigene] Oral contraceptive pill decreases [lamotrigene]

What are the uses of levetiracetam?

Focal seizures

What is the mechanism of action of levetiracetam?

**Synaptic vesicle protein inhibition** - Reduces synchronised burst firing without affecting neuronal excitability - reduced glutamate release from excitatory neurone

What are adverse drug reactions of levetiracetam?

Anxiety Drowsiness Dizziness

What are important drug drug interactions of levetiracetam?

CNS depressants

What is status epilepticus?

Condition where epileptic fits follow one another without recovery on consciousness between them

When is a seizure a medical emergency

- lasts >5 minutes - status epilepticus (multiple seizure without recovery in between)

What is the stepwise approach of status epilepticus treatment

- benzodiazepines - 2nd dose benzodiazepine - 2nd line - levetiracetam or phenytoin or sodium valproate - alternative 2nd line agent - barbiturates + general anaesthesia 5-10 minute interval between each

What drug class should be administer first in the treatment of status epilepticus?

Benzodiazepines

Examples of benzodiazepiness

Diazepam Lorazepam Midazolam

Compare the duration action of midazolam + diazepam

**midazolam**: short actin **diazepam**: longer acting

What benzodiazepine is better in hepatic dysfunction + why?

**lorazepam** Phase 2 metabolism

What are the uses of benzodiazepines?

Anxiety Status epilepticus Insomnia associated with anxiety

What is the mechanism of action of benzodiazepines

- potentiate GABA activity at GABA_A receptor - hyperpolarisation of cell via increased Cl- influx

What are adverse drug reactions of benzodiazepines?

Ataxia Depression Drowsiness Hypotension Muscle weakness Sleep disorders

What can high doses of benzodiazepines cause?

Respiratory depression

Why should benzodiazepines be used short term?

Addictive Risk of overdose

What are important drug drug interactions of benzodiazepines?

Other CNS depressants

What is sudden unexplained death in epilepsy SUDEP?

Deaths in people with epilepsy who are otherwise healthy that are not caused by known causes

Relationship between carbamazepine + CYP450 enzymes

It induces CYP3A4 so increases its own metabolism

Describe a focal seizure

- remains conscious - arises in one hemisphere of the brain - split into aware + impaired awareness - can have motor onset *e.g. jolting* - or non motor onset *e.g. smacking lips*

Describe an simple focal seizure

- conscious - normal awareness - no post ictal symptoms - arises in one hemisphere

What is a secondary generalised seizure?

Starts focal but then comes generalised

Describe a complex focal seizure

- conscious but impaired awareness - can get post ictal symptoms *e..g confusion, groggy* - often in temporal lobe - arises in one hemisphere

Describe a generalised seizure

Arises in both hemispheres Often unconscious

Types of generalised onset seizures

Tonic clonic Tonic Clonic Atonic Myoclonic (can be conscious) Absence (can be conscious)

What is a myoclonic seizure?

Seizure of muscle or groups of muscles Can be conscious

Examples of post ictal symptoms

Embarrassment Confusion Fatigue Headache Muscle aching/pain Frustration

What is an aura?

A warning that a seizure in coming

Diagnosis of epilepsy

- electroencephalogram - MRI - detailed patient history + eyewitness accounts

What needs to be considered in women on COCP when prescribed carbamazepine?

Carbamazepine increases action of CYP450 enzymes on COCP so higher dose of COCP is needed

Uses of phenytoin

Second line status epilepticus

Epilepsy + Anti Epileptic Drugs Flashcards

(70 cards)