Anti-epileptics Flashcards
Sodium channels are NOT involved in which of the following seizures?
A. Generalized tonic-clonic
B. Absence
C. Focal
D. Complex focal
B. Absence
Remember that these seizures are mediated by abnormal activity of T-type Ca++ channels in the thalamus.
Patient presents w/ tonic-clonic seizures. What is the DOC and its MOA?
Phenytoin. It binds to Na channels in the inactive state, thereby slowing the transition to the resting state and increasing the refractory period of the Na channel.
If you gave a drug that induces P450 along with phenytoin, what would the effect be?
Phenytoin is metabolized by P450, so a drug that induces P450 function will cause higher metabolism rates of phenytoin, thereby decreasing its levels.
Phenytoin also induces P450. Which of the following drugs are metabolized by P450 and would therefore have their levels decreased in the presence of phenytoin?
A. Statins
B. Alcohol
C. Oral contraceptives
C. Oral contraceptives
What is the DOC for focal seizures?
A. Ethosuxamide
B. Diazepam
C. Carbamazepine
D. Methylphenidate
C. Carbamazepine. It acts in the same way as phenytoin, binding to inactivated Na channels and keeping them inactivated longer, leading to longer refractory periods.
Skin rash is a major adverse effect of which drug?
A. Lamotrigine
B. Phenytoin
C. Carbamazepine
D. Ethosuxamide
A. Lamotrigine
This can cause some serious stuff such as life-threatening dermatitis and Stevens-Johnson Syndrome
What is the MOA of ethosuxamide?
A. Inhibit T-type Ca channels
B. Bind to Na channels in the inactive state
C. GABA agonist
D. Piezoelectricity
A. Inhibit T-type Ca channels
This is the first line tx for absence seizures
If ethosuxamide did not work to tx absence seizures, what would be the next drug on your list?
Valproic acid. This guy can do it all. It blocks Na channels, T-type Ca channels (hence its effectiveness in absence seizures), and increases GABA transmission.
What is the MOA of gabapentin and pregabalin in the tx of seizures?
These guys inhibit high voltage Ca channels in presynaptic terminals. As you know, Ca channels need to open in the terminals to release NTs, so by blocking these channels, you decrease the release of NTs (presumably excitatory NTs).
A patient presents with chronic liver disease and focal seizures. What is the DOC?
A. Phenytoin
B. Lamotrigine
C. Ethosuxamide
D. Pregabalin
D. Pregabalin
This is metabolized by the kidneys, so it can be given to pts w/ hepatic impairment.
What type of seizures can you tx w/ benzodiazepines?
Focal and tonic-clonic seizures in the short term. BZs cannot be used in the long term because of their s/e such as dizziness, drowsiness, and ataxia. Remember that they are also used to tx short-term anxiety issues such as panic disorder.
Which of the following BZs can be used to tx absence seizures?
A. Diazepam
B. Lorazepam
C. Clonazepam
D. Midazolam
C. Clonazepam
This drug is able to indirectly inhibit T-type Ca channels associated w/ absence seizures. Only used in the acute phase bc of its s/e.
A patient is being treated for focal epilepsy with vigabatrin. What does the Dr. have to monitor while administering this med?
Visual field testing. Vigabatrin can cause diffuse atrophy of the peripheral retinal nerve fiber layers, leading to visual field defects.
The MOA of felbamate is…
…inhibition of glutamate NMDA receptors. It is used to tx refractory epilepsy.
Felbamate has some serious adverse effects. What are they?
Aplastic anemia and liver failure
