Epilepsy & Anti-seizure Drugs Flashcards
What percentage of epilepsy patients are therapy-resistant?
25-40%
What is a seizure?
a finite clinical manifestations of abnormal and excessive excitation of a population of cortical neurons
What is epilepsy?
syndrome characterized by chronic, recurrent seizures unprovoked by systemic or neurologic insults
What age ranges are most commonly diagnosed with epilepsy?
Pediatric and elderly patients are most likely affected by epilepsy
What is the most common inherited etiology of epilepsy?
Faulty ion channels
There are partial seizures and generalized seizures. What are the three types of partial seizures?
- Simple partial
- Complex partial
- Secondarily generalized
What are the three types of generalized seizures?
- Tonic-clonic (“grand mal”)
- Absence (“petit mal”)
- Atonic (“drop”)
What is the difference between a simple partial and complex partial seizure?
A simple partial seizure the person is aware and responsive. Complex partial the person may have memory impairment.
Describe a tonic-clonic generalized seizure.
Tonic phase: patient loses control of mind/body and stiffens
Clonic phase: patient jerks limbs
seizure lasts a few minutes
How long does the postictal phase last after a grand mal seizure?
minutes to hours
Describe a generalized absence seizure.
The patient stares for 2-15 seconds with loss of memory
What are some ideal properties of an Anti-Seizure Drug?
wide therapeutic index, long half-life, water soluble
When modifying a drug’s therapeutic index, what does a metabolism inhibitor do?
It will inhibit the metabolism/clearance of the drug causing the plasma concentration to near toxicity.
When modifying a drug’s therapeutic index, what does a metabolism inducer do?
It will enhance metabolism/clearance of the drug causing the plasma concentration to (lower) near subtherapeutic levels.
What are the three main mechanisms for ASDs?
- Enhancing GABA-mediated inhibition
- reduction of excitatory transmission (i.e glutamate)
- modify ionic conductance (i.e. Na, Ca, K)
What is Carbamazepine indicated to treat?
Simple & Complex partial seizures; and Tonic-clonic seizures
Carbamazepine should be avoided in patients with what type of seizure?
Generalized absence
What are common side-effects of carbamazepine?
blurred/double vision, cognitive impairment. (rare: stevens-johnson syndrome)
Someone on carbamazepine shouldn’t drink what?
Grapefruit juice - its a metabolism inhibitor
What drug is indicated for treating only uncomplicated absence seizures?
Ethosuximide (Zarontin™)
What are two special considerations to think about when prescribing Ethosuximide?
- narrow clinical spectrum (absence seizures only)
- very long half life: ~40hr
What is Phenytoin (Dilantin™) indicated to treat?
Simple and Complex partial; Tonic-clonic generalized
What is one side effect of Phenytoin that we might see in our dental office?
gingival hyperplasia
What should Phenytoin never be prescribed to treat?
Absence-type seizures
Why should you frequently check plasma concentrations of Phenytoin?
Phenytoin follows zero-order kinetics at high doses (exponential increase in concentration over time)
What is Topiramate (Topamax™) indicated to treat?
Simple & Complex partial; Tonic-clonic generalized & Lennox-Gastaut Syndrome
What are three common and one uncommon side effects of Topiramate?
common: word recall problems, renal calculi, and weight loss. uncommon: open-angle glaucoma
What is Valproic Acid (Depakote™) indicated to treat?
Simple & Complex partial; Absence, atypical Absence, Myoclonic epilepsy, and Tonic-clonic generalized seizures
Toxic doses of Valproic Acid will cause what?
Rene-like syndrome and/or hepatic failure
What is a common side effect of Valproic acid?
weight gain
Patients with what condition should NOT be prescribed Valproic Acid?
hepatic disease or significant hepatic dysfunction
Why shouldn’t you give Valproic acid to a pregnant patient?
It increases the risk for neural tube defects like Spina bifida (*Category D risk)
If your patient has cirrhosis and experiences Tonic-clonic seizures, what are your drug options?
Phenytoin, Carbamazepine, or Topiramate
If your patient has absence-type seizures, what drug(s) could you probably prescribe?
Ethosuximide, or Valproate
If your patient has simple partial seizures, what drugs could you possibly prescribe?
Carbamazepine, Phenytoin, Valproate, or Topiramate
If your patient has lennox-gastaut syndrome, what drug(s) would you prescribe?
Topiramate
Your obese patient suffers from complex partial seizures. What could you prescribe to them to help both problems?
Topiramate (weight loss is common)
