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Flashcards in Epilepsy Deck (40):
1

Where does Phenytoin act?

they inhibit voltage-gated sodium channels

2

Where does carbamazepine act?

they inhibit voltage-gated sodium channels

3

Where does lamotrogine act?

they inhibit voltage-gated sodium channels

4

Where do benzos and barbituates act?

they stimulate GABA receptors

5

therapy for generalised tonic clonic?

Carbamazepine, lamotrigine, sodium valproate

6

therapy for tonic or atonic?

sodium valproate, lamotrigine

7

absences?

ethosuximide, lamotrigine, sodium valproate

8

myoclonic?

levetiracetam
sodium valproate
topiramate

9

focal?

carbamazepine, lamotrigine, levetiracetam, sodium valproate, oxcarbazepine

10

drug treatment for status eplipticus ?

benzos:
IV lorazepam
diazepam (rectal if community)
midazolam (buccal if community)

more severe: IV
phenytoin
clonazepam
phenobarbital

11

Drug that's associated with anterograde amnesia?

miazolam

12

Clonazepam is used for?

severe status epilepticus
second line for tonic clonic, absence, myoclonic

13

route and dosaging for diazepam?

IV or rectal
10mg, then 10mg after 10 minutes at a rate of 1ml (5mg ) per minute

14

route for midazolam? dosage??

buccal
10mg, then 10mg after 10 minutes at a rate of 1ml (5mg ) per minute

15

is IV midazolam ok for children?

children: IV is not licensed for use in status epilepticus or febrile
convulsions

16

What is phenobarbital?

it's a long acting barbituate used to treat all types EXCEPT typical absence seizures

17

adverse effects of phenobarbital?

Cognition, tolerance to therapeutic doses
• Serious seizure exacerbation upon withdrawal
• Skin rashes, ataxia and folate deficiency
• Behavioural disturbances (especially in children)
• Increased risk of connective tissue disorders like
Dupuytren’s contracture

18

How would you dosage phenobarbital in status epilepticus?
Be careful why?

10 mg/kg (max1 g/dose ), at a rate not more than 100 mg/minute

Toxicity varies between patients; tolerance will develop with chronic use,
barbiturates decrease gut motility, which may lead to slow onset and
worsening of symptoms.
• Drowsiness, dysarthria, ataxia, nystagmus and disinhibition. There may also
be coma, cardiovascular collapse

19

What should you avoid with phenobarbital?

alcohol--- CNS effects

20

Prescriber of phenobarbital should be wary of reduced efficacy of which drugs?

CHC
aminophylline
apixaban
ciclosporin
eplerenone
everolimus
folic acid
ranolazine

21

would you use phenytoin in generalised or myoclonic seizures?

no, it's not effective

22

How does phenytoin help as an emergency medication in SE?

It appears to stabilise rather than raise the seizure threshold and prevents spread of seizure activity rather than abolish the primary focus of seizure discharge.

23

mechanism of phenytoin?

unclear but proposed..
Non-synaptic effects to reduce sodium conductance, enhance active sodium extrusion, block repetitive firing and reduce post-tetanic potentiation
• Post-synaptic action to enhance GABA-mediated inhibition and
reduce excitatory synaptic transmission
• Pre-synaptic actions to reduce calcium entry and block release
of neurotransmitter

24

as a prescriber what should you remember when prescribing phenytoin?

it's a potent enzyme inducer
contraindications: Hypersensitivity and acute porphyria with IV second- and third-degree heart block; sino-atrial block; sinus bradycardia; Stokes-Adams syndrome

side effects:
• Suicidal ideation, skin rashes. Dose related
nystagmus, ataxia, lethargy are very common.
• Gum hypertrophy and acne are well
recognised side effects which should be taken
into account when prescribing
• Folate deficiency, osteomalacia, cerebellar
atrophy and bone marrow depression can
occur

25

avoid prescribing what with phenytoin?

amiodarone: peripheral neuropathy
apixaban (reduces its efficacy)
carbamazepine (reduces)
ciclosporin (reduces)
CHC (reduces)
dabigatran (reduces)
enteral feeds (reduces efficacy of phenytoin)
flucanazole (increases its concnetration)

26

contraindications of carbemazepine?

Hypersensitivity to carbamazepine, or structurally
related drugs, e.g. tricyclic anti-depressants.
• Patients with atrioventricular block, a history of
bone marrow depression or a history of hepatic
porphyria's.

27

side effects of carbemazepine?

Blurred vision, somnolence and dizziness, oedema,
fluid retention, weight increase, hyponatraemia
Decreased platelet or white blood cell counts occur
occasionally to frequently in association with use of
carbamazepine.
Agranulocytosis and aplastic anaemia have been
associated with carbamazepine (although rare)

28

what can carbemazepine abolish the activity of?

Anticoagulants, antidepressants, antifungals, antipsychotics, contraceptives and
immunosuppressants.
Co-administration with diuretics might induce hyponatremia
Lithium in combination might enhance neurotixicty

29

which drugs will increase concentrations of carbemazepine?

enzyme inhibitors:
cimetidine
antifungal agents (ketoconazole)
erythromycin
ciclosporin
Psoralen: (from grape fruit juice, interaction with DHPs and statins)

this takes 1-2 days and reverses quickly!

30

which drugs will decrease concentrations of carbemazepine?

Barbiturates
Rifampicin
Griseofulvin
Phenytoin
Ethanol
Carbamazepine –autoinduction!
St John’s Wort

takes weeks!

31

Carbemazepine interactions?

alcohol- hepatotoxicity risk
TCAs and SSRIs: high risk of hypoantremia
Diuretics: high risk of hypoantremia
Apixaban (reduced levels)
Atrovastatin (hepatotoxicity)
ciclosporin (reduced)
Cimetidine (increased)
Fluconzole (hepatotoxicity)
Clarithromycin (increased concentrations of carbemazepine)
contraception less effective


32

Epilieptics at a child bearing age..

careful with carbemazepine, lamotrigine and phenytoin's effects on contraception
sodium valproate and pregnancy

33

what is sodium valproate?

A first line drug choice in generalised, absence or partial seizures, especially if these occur as part of the syndrome of generalised epilepsy.
The most likely mode of action for Epilim is potentiation of the inhibitory action of gamma amino-butyric acid (GABA) through an action on the further synthesis or further metabolism of GABA.

34

sodium valproate contraindications?

Pregnancy as it can cause foetal abnormalities
therapy should be changed if a woman wants to
become pregnant.
Active liver disease or a history of hepatic
dysfunction, in cases of hypersensitivity or
porphyria.

35

side effects of sodium valproate?

• Nausea, diarrhoea and weight gain, tremors,
dysmenorrhoea
• Transient confusion on imitation of therapy,
alopecia, skin rash and thrombocytopenia
• Fatal hepatic and pancreatic failure can occur
although this is rare

36

what is lamotrigine?

One of the “newer” classes of AED it can
be used first line for patients with partial
seizures with or without generalisation
or tonic-clonic convulsions
• It inhibits sustained repetitive firing of
neurones and inhibits release of
glutamate
• (the neurotransmitter which plays a key role
in the generation of epileptic seizures).
• It can also be used to teat bipolar
disorder (FYI) always worth confirming
the indication with your patient.

37

how is lamotrigine metabolised and excreted?

not by first pass metabolism, not affected by liver enzymes
eliminated by kidney

38

contraindications of lamotrigine

Hypersensitivity, severe liver or renal
impairment

39

side effects of lamotrigine?

• Personality changes, headache nausea and
vomiting
• Skin rashes including Stevens–Johnson
syndrome and toxic epidermal necrolysis have
been seen with lamotrigine although this is
associated with:
• High initial doses of lamotrigine and exceeding
the recommended dose escalation of
lamotrigine therapy
• Concomitant use of valproate

40

Lamotrigine interactions?

alcohol (CNS depression)
baclofen (CNS depression)
carbemazepine
CHC
desmopressin (hypantremia risk)
opioids (CNS depression)
phenytoin (lamotrigine decrease)