Anticonvulsants Flashcards
What is the main drug used for absence seizures?
ethosuximide but valproic acid can be used as well
What drug do you need to remember is good for the treatment of status epilepticus?
IV benzodiazepines
MOA phenytoin?
Decreased axonal conduction by preventing Na+ influx through fast Na channels
MOA of felbamate?
NMDA receptor blocker
MOA of ethosuximide?
Decreased presynaptic Ca2+ influx. through type T channels in thalamic neurons
MOA of lamotrigine?
AMPA receptor blocker and Na+ channels
MOA of topiramate?
AMPA receptor blocker (glutamate receptors)
Blocks Na+ channels
enhances GABA activity
MOA of carbamazepine?
Decreased axonal conduction by preventing Na+ influx through fast Na channels
MOA of valproic acid
- Decreased presynaptic Ca2+ influx. through type T channels in thalamic neurons (blocks T-type Ca2+ channels)
- inhibition of GABA transaminase
- blocks voltage gated Na+ channels in their inactivated state
What are the S/Es of phenytoin/contraindications?
CNS depression
gingival hyperplasia
hirsutism
osteomalacia (dec vit. D)
megaloblastic anemia ( dec folate)
aplastic anemia (check hematology lab results)
contraindications:
pregnancy (teratogen)
What teratogenic effect does phenytoin produce in the fetus?
cleft lip and palate
Uses for carbamazepine?
seizures
DOC for trigeminal neuralgia
BPD
S/E of carbamazepine? Contraindications?
CNS depression
osteomalacia
megaloblastic anemia
aplastic anemia
exfoliative dermatitis
inc. ADH secretion (dilution hyponatremia)
Contraindications:
pregnancy (teratogen)
What teratogenic effect does carbamazepine produce in the fetus?
cleft lip and palate; spina bifida
What are the uses of valproic acid?
seizures
BPD
migraine prophylaxis
What affect does valproic acid have the cytochrome P450?
inhibits cytochrome P450
What is the S/E profile of valproic acid? Contraindicaitons?
hepatotoxicity (from toxic metabolite)
thrombocytopenia
pancreatitis
alopecia
VALPROATE
Vomiting
Alopecia
Liver Toxicity
Pancreatitis/Pancytopenia
Retain fat
Oedema
Appetite increase
Tremor
Enzyme Inhibitor
Contraindications:
Pregancy (teratogen)
What is the teratogenic effect associated with using valproic acid?
spina bifida
S/E profile of lamotrigine?
SJS
S/E of topiramate?
weight loss
S/E of felbamate
aplastic anemia
MOA gabapentin.
inhibit the action of α2δ-1 subunits, thus decreasing the density of pre-synaptic voltage-gated calcium channels and subsequent release of excitatory neurotransmitters
basically affects calcium channels and neurotransmitter release leading to GABA effects
Gabapentin uses.
seizures and neuropathic pain (such as postherpetic neuralgia)
How may many anticonvulsants reduce the efficacy of OC’s?
Oral contraceptives are P450 substrates and many anticonvulsants are P450 inducers
