Anti-epileptics: Uses, actions and side effects Flashcards
Phenytoin moa
binds to sodium channels increasing their refractory periods
phenytoin effect on P450 system
INDUCER of P450 system
phenytoin initial side effects
initially: dizziness, diplopia, nystagmus, slurred speech, ataxia
later: confusion, seizures
phenytoin chronic side effects
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
phenytoin idiosyncratic side effects
fever
rashes, including severe reactions such as toxic epidermal necrolysis
hepatitis
Dupuytren’s contracture*
aplastic anaemia
drug-induced lupus
phenytoin effects on foetus
associated with cleft palate and congenital heart disease
sodium valproate moa
increasing GABA activity
Sodium valproate effect on P450 system
P450 inhibitor
sodium valproate adverse effects
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
treatment for hyperammonemic encephalopathy
L-carnitine
carbamazepine MOA
binds to sodium channels, increases their refractory period
carbamazepine effect on P450 system
P450 enzyme inducer
carbamazepine adverse effects
dizziness and ataxia
drowsiness
headache
visual disturbances (especially diplopia)
Steven-Johnson syndrome
leucopenia and agranulocytosis
hyponatraemia secondary to syndrome of inappropriate ADH secretion
carbamazepine autoinduction
hence when patients start carbamazepine they may see a return of seizures after 3-4 weeks of treatment.
lamotrigine moa
sodium channel blocker