Anti-epileptics: Uses, actions and side effects Flashcards

1
Q

Phenytoin moa

A

binds to sodium channels increasing their refractory periods

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2
Q

phenytoin effect on P450 system

A

INDUCER of P450 system

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3
Q

phenytoin initial side effects

A

initially: dizziness, diplopia, nystagmus, slurred speech, ataxia
later: confusion, seizures

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4
Q

phenytoin chronic side effects

A

common: gingival hyperplasia (secondary to increased expression of platelet derived growth factor, PDGF), hirsutism, coarsening of facial features, drowsiness
megaloblastic anaemia (secondary to altered folate metabolism)
peripheral neuropathy
enhanced vitamin D metabolism causing osteomalacia
lymphadenopathy
dyskinesia

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5
Q

phenytoin idiosyncratic side effects

A

fever
rashes, including severe reactions such as toxic epidermal necrolysis
hepatitis
Dupuytren’s contracture*
aplastic anaemia
drug-induced lupus

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6
Q

phenytoin effects on foetus

A

associated with cleft palate and congenital heart disease

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7
Q

sodium valproate moa

A

increasing GABA activity

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8
Q

Sodium valproate effect on P450 system

A

P450 inhibitor

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9
Q

sodium valproate adverse effects

A

gastrointestinal: nausea
increased appetite and weight gain
alopecia: regrowth may be curly
ataxia
tremor
hepatotoxicity
pancreatitis
thrombocytopaenia
hyponatraemia
hyperammonemic encephalopathy: L-carnitine may be used as treatment if this develops

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10
Q

treatment for hyperammonemic encephalopathy

A

L-carnitine

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11
Q

carbamazepine MOA

A

binds to sodium channels, increases their refractory period

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12
Q

carbamazepine effect on P450 system

A

P450 enzyme inducer

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13
Q

carbamazepine adverse effects

A

dizziness and ataxia
drowsiness
headache
visual disturbances (especially diplopia)
Steven-Johnson syndrome
leucopenia and agranulocytosis
hyponatraemia secondary to syndrome of inappropriate ADH secretion

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14
Q

carbamazepine autoinduction

A

hence when patients start carbamazepine they may see a return of seizures after 3-4 weeks of treatment.

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15
Q

lamotrigine moa

A

sodium channel blocker

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16
Q

lamotrigine adverse effects

A

Steven-Johnson syndrome

17
Q

topiramate moa

A

blocks voltage-gated Na+ channels
increases GABA action
carbonic anhydrase inhibition: this results in a decrease in urinary citrate excretion and formation of alkaline urine that favours the creation of calcium phosphate stone

18
Q

topiramate effect on p450 system

A

inducer of the P450 enzyme CYP3A4

19
Q

topiramate adverse effects

A

reduced appetite and weight loss
dizziness
paraesthesia
lethargy and poor concentration
rare but important: acute myopia and secondary angle-closure glaucoma

20
Q

ethosuximide moa

A

blocks T-type calcium channels in thalamic neurons

21
Q

1st line treatment generalised tonic clonic

A

males: sodium valproate
females: lamotrigine or levetiracetam

22
Q

first line treatment focal seizures

A

first line: lamotrigine or levetiracetam

23
Q

second line treatment focal seizures

A

second line: carbamazepine, oxcarbazepine or zonisamide

24
Q

first line treatment absence seizures

A

ethosuximide

25
Q

Second line treatment absence seizures

A

male: sodium valproate
female: lamotrigine or levetiracetam
carbamazepine may exacerbate absence seizures

26
Q

myoclonic seizures treatment

A

males: sodium valproate
females: levetiracetam

27
Q

tonic or atonic seizures management

A

males: sodium valproate
females: lamotrigine