Flashcards in Dr. Smith Epilepsy and Anti seizure drugs Deck (78):
What is a finite clinical manifestation of abnormal and excessive excitation of a population of cortical neurons known as?
What is a syndrome characterized by 2 or more recurrent seizures that are unprovoked by a systemic or neurologic insults known as?
What is a sequence of events that convert normal neuronal networks into a hyperexcitable networks known as?
What is a continuous seizure lasting more than 30 min or 2 or more seizures without full recovery of consciousness between them known as?
How many people will be diagnosed with epilepsy throughout a lifetime?
1 in 26
What characterizes epilepsy?
-2 or more (recurrent) seizures that are unprovoked
Any seizure lasting more than 5 minutes is treated clinically as what?
What is the most common causes of epilepsy in pediatric patients?
-Perinatal and neonatal insults
What are the most common causes of epilepsy in adults?
What are the most common causes of epilepsy in the elderly?
What are common seizure precipitants?
-Metabolic and or electrolyte imbalance
-Reduction or inadequate ASD treatment
-High fever or CNS infection
-Concussion and or closed head injury
What are the two subsets of etiologies of epilepsy?
What are the three types of partial seizures?
What type of partial seizure is a single focus and the pt is fully aware and responsive?
What type of partial seizure has a focal onset with local spread and the pt is initially aware and responsive but may develop some memory impairment if limbic system is involved?
What are some common stimulant seizure precipitants?
What type of partial seizure is when the pt is initially aware and responsive but them loss of responsiveness and any memory as seizure then fully generalizes to involve the entire cortex, midbrain and thalamus?
What is the loss of awareness and lack of responsiveness, generalization from onset known as?
What are different types of generalized Seizures?
-Tonic-clonic (can be tonic or clonic as well)
What does tonic mean?
What does clonic mean?
What is the phenotype of a simple partial seizure?
-Depends on areas of focal cortical involvement
How are the Foci of simple partial seizures confirmed?
If the motor cortex is involved in a simple partial seizure what does it look like?
If the somatosensory cortex is involved in a simple partial seizure what does it look like?
If the occipital cortex is involved in a simple partial seizure what does that produce?
How long do simple partial seizures typically last?
-Less than 90 seconds
What is a pt like during a simple partial seizure?
-Normal awareness, memory and consciousness throughout the seizure
How does a complex partial seizure spread?
-Locally or Bilaterally
What might become impaired during a complex partial seizure?
What is the duration of a complex partial seizure?
-Less than 120 seconds
If a complex partial seizure fully generalizes what is it known as?
-Secondarily generalized seizure
How can secondarily generalized seizures begin?
-Simple or complex partial seizures
How long does a secondarily generalized seizure last?
-Less than 240 seconds
What is the Postictal phase?
-Confusion, Somnolence, with or without transient focal deficit can last for minutes up to hours
Absence seizures probably represent abnormal interactions between what?
-Cortical and thalamic transmissions
What does a typical absence seizure look like?
-Impaired awareness and responsiveness for about 2 - 15 seconds
What are the three mechanisms of action for most commonly used ASDs?
-Enhancement of GABA mediated inhibition
-Reduction of excitatory transmission (glutamate)
-Modification of ionic conductance (Na, Ca 2+, K)
What is the purpose of the modification of ionic conductance
-Targeted at slowing neurotransmission in hopes of slowing or preventing seizure spread
How is the therapeutic index calculated?
-Median toxic dose/ median effective dose at any given time
What does the modulation of voltage dependent Na + or Ca 2+ channels lead to?
-Secondary inhibition of neurotransmitter release (particularly glutamate)
If you take a CYP450 inhibitor what can happen with the therapeutic index?
-You can start heading towards the toxic dose
When would you use Carbameaepine (tegretol)?
-Partial simple or complex seizures
-Generalized tonic-clonic seizures
Carbamazepine is a great drug for partial epilepsy but potential for what is high?
-Drug drug interaction
What is the Mechanism of action of Carbamazepine (Tegretol)?
-Blocks voltage-gated Na+ channels to inhibit repetitive firing in neurons
What is a rare side effect from carbamazepine?
-Stevens Johnson syndrome?
-What drug should you avoid in absence seizures?
If you give Carbamazepine to someone with absence seizures what might happen?
-May aggravate spike wave seizures
What are the symptoms of Stevens johnson syndrome?
-Painful lesions in the mucous membranes in the mouth and lips
-Spreads rapidly to face, trunk, arms, legs and feet
What pts are most at risk for getting stevens johnson syndrome?
-Pts on sodium channel blocker ASDs
What can raise Carbamazepine levels in plasma?
-Grapefruit juice by inhibiting its breakdown by CYP3A4
What does Carbamazepine do to CYP3A4 enzyme?
-Inhibits it leading to a decrease in Carbamazepine metabolism leading to increases in plasma levels of the drug
When do you use Ethosuximide (Zarontin)?
-Uncomplicated absence only
What drug do you use for uncomplicated absence only ?
What side effects does Ethosuximide have?
-May worsen partial and tonic clonic seizures
-Minor weight loss
T/F Ethosuximide has a short half life
-Long half life
What is the mode of action of ethosuximide?
-Reduces T-type Ca2+ channel currents in thalamic pacemaker neurons
What is Phenytoin (Dilantin) used for?
-Partial simple and complex
-Generalized tonic clonic
What is a dentally related side effect of Phenytoin (Dilantin)?
What type of kinetics does Phenytoin have at high doses?
What is Phenytoin contraindicated for?
What is the mode of action of phenytoin?
-Blockade of Na+ channel during repetitive firing
What must you do if a drug has zero order kinetics?
-Monitor plasma levels often and titrate dose as needed
What do you use Topiramate (Topamax) used for?
-Partial simple complex
What are side effects of topiramate (topamax)?
-Word recall problems
-open angle glaucoma (not very common though)
What can topiramate (topamax) do to estrogen?
-Increase metabolism making oral contraceptives less effective (must use secondary means of birth control to avoid pregnancy)
Topiramate has multiple Modes of action and is broad spectrum, what are the MOA?
-blocks repetitive firing of voltage gated Na+
-Inhibits Ca2+ currents
-Inhibits AMPA/kainate receptors
-Potentiates GABA currents
What is Valproic Acid (Depakote) used for?
Generalized atypical absence
-Partial simple and complex
What are common side effects of valproic acid (Depakote)?
-Reye-like syndrome: hepatic failure
What is Valproic acid contraindicated in?
-pts with hepatic disease or significant hepatic dysfunction
What are increased risks of Valproic Acid?
What is the pregnancy risk for Valproic acid?
-Category D risk
What are three ASD drugs used for partial seizures?
-Topiramate (if secondarily generalized)
What ASD drugs are used for generalized onset tonic clonic seizures?
What ASD drugs are used for absence seizures?
What ASD drugs are used for Status epilepticus?
What are the principles of ASD treatment?
-Match proper drug to seizure type
-Try monotherapy first
-monitor plasma levels of drugs
-Tailor therapy to individual patient