Anticonvulsants Flashcards
What are the general guidelines for epileptic drug use?
Monotherapy, don’t suddenly withdraw or start with a high dose, watch out for side effects, toxicity and individual variation
What anticonvulsant would be used for postherpetic neuralgia?
Gabapentin, lidocaine, pregabalin
What anticonvulsant would be used for diabetic neuropathy?
Carbamazepine, duloxetine, phenytoin, gabapentin, lamotrigine, pregabalin
What anticonvulsant would be used for HIV neuropathy and central post-stroke pain?
Lamotrigine
What anticonvulsant would be used for trigeminal neuralgia?
Carbamazepine, lamotrigine, oxcarbazepine
What is the best medication to use for focal onset seizures?
Carbamazepine, phenytoin
What is the best meds to use for general onset (tonic-clonic) seizures?
Valproate, topiramate
What is the mechanism of action for carbamazepinem, valproate, lamotrigine and phenytoin?
Inactivation of the sodium channel intracellularly
What are the general characteristics for phenytoin?
Oldest nonsedative, fosphenytoin (prodrug) better use for parenternal use, alters Na, Ca2+, K+, inhibits high frequency repetitive firing
What is the toxicity to phenytoin?
Ataxia, nystagmus, cognitive impairment, gingival hyperplasia, coarsing of facial features, exacerbates absence seizures, decerebrate rigidity
What are the therapeutic uses for carbamazepine?
All partial seizures, highly effective for tonic-clonic
What are some features of crabamzepine?
Binds to adenosine receptors, inhibits uptake of NE (not GABA) potentiate postsynaptic effects of GABA, metabolite active
What is the toxicity to carbamazepine?
Granulocyte suppression, aplastic anemia, exacerbates absence seizures
What are the features of oxcarbazepine?
Active metabolite, first choice for partial and generalized as adjunct
What is the toxicity to oxcarbazepine?
Hyponatremia, less hypersensitive of induction of hepatic enzymes
What are the features of lamotrigine?
Add for for valproic acid, T1/2=24 hrs, blocks Na channel firing
What is lamotrigine used for?
Myoclonic, atonic and generalized seizures in childhood + absence attacks
What is the toxicity for lamotrigine?
Life threatening rash “Steven Johnson”
What are the features of levetiractam?
Broad spectrum, binds to synpatic vesicular protein SV2A, modifies release of GABA and glutamate
What is levetiractam used for?
Myoclonic, atonic, generalized seizures in childhood and atypical absence
What are the side effects of levetiracetam?
Somnolence, ataxia, anxiety, agitation, dec RBC
What is phenobarbital used for?
50% favorable response to simple partials
Recurrent tonic-clonic
What is the toxicity for phenobarbital?
Sedation, cognition impairment
CAN WORSEN absence and atonic seizures
What are the features of phenobarbital?
Blocks GLU (AMPA), prolongs opening of Cl channels
What are the features of ezogabine?
Adjunct therapy for partial seizures and refractory partial epilepsy in pts
First AED to target open voltage-gated K channels
Enhances GABA
What are the side effects of ezogabine?
Urinary retention, somnolence, dizziness, confusion
What are the features of gabapentin?
Adjunct in partial and generalized tonic-clonic
Analog of GABA, dec neuronal Ca currents by binding of a-2-delta subunits
What are the features of topiramate?
Rapidly absorbed, T1/2=20-30 hrs
Blocks firing of neurons and Na channels
Potentiates GABA, depress action of kainate on AMPA
What is the toxicity of topiramate?
Weakness carbonic anhydrase inhibitor, paresthesias, teratogenic
What are the features of tiagabine?
Nipecotic acid, t1/2 = 5-8 hrs. adjunctive therapy, GABA uptake inhibitor to glial cells
Partial seizures
What is the toxicity of tiagabine?
Ab pain w/ nausea, tremor, psychosis, skin rash
What are the features of zonisamide?
Sulfanmide, T1/2 = 1-3 days
Tonic-clonic seizures
Inactivation of Na channels, bind GABA
What is the toxicity of zonisamide?
Anorexia, renal stones, metabolized by CYP3A4
