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Antiepilieptic Drugs
Drugs for epilepsy
Question | Answer |
---|---|
What is the etiology of epilepsy? | excessive excitability of neurons in the CNS |
what is a focus? | a group of excitable neurons |
what are the 4 mechanisms of action for antiepileptic drugs? | (1) suppression of sodium influx (2) calcium influx suppression (3) antagonism of glutamate (4) agonizing GABA |
what is needed to diagnose epilepsy? | EEG |
when organizing drug therapy for a pt with epilepsy, when the first drug doesn't work what does the prescriber do? waht if the second drug doesn't work? | if the first doesn't work, stop it and start a second. if the second doesn't work, stop it and start a third OR start a combo |
antiepileptic drugs increase your risk for something, what is it? | suicide |
Serum level: Carbamezepine [Tegretol] | 4-12 |
Serum level: Phenytoin [Dilantin] | 10-20 |
Serum level: valporic acid [Depakote] | 40-100 |
Serum level: Phenobarbital | 15-45 |
Serum level: gabapentin [neurontin] | 12-20 |
Serum level: Lamotrigine [Lamictal] | 3-14 |
Serum level: oxcarbazepine [trileptal] | 3-40 |
Serum level: Levetiracetam [Keppra] | 10-40 |
Serum level: pregabalin [Lyrica] | NA |
Serum level: Topiramate [Topamax] | 5-25 |
what is the mechanism of action for Dilantin? | inhibits sodium channels |
what are the dosing intervals for Dilantin? | dependent on dose (lower dose=shorter half life) |
metabolism of Dilantin | minimal metabolism by liver --> HIGH risk for toxicity |
what is an alternate use for Dilantin? | dysrhythmias |
Can you push Dilantin? | yes, but only over at least 5 minutes! |
Antiepileptic drugs decrease the effects of some drugs, what are they? | Birth control, anticoagulants |
How should you discontinue Dilantin? | gradually!!! to avoid seizures |
What are the adverse effects of Dilantin? | CNS: Nystagmus GINGIVAL HYPERPLASIA SKIN RASH! - STOP DRUG!! teratogen dysrhythmias, hypotension |
What are the drug interactions of Dilantin? | decrease effects of BC/anticoagulants/glucocorticoids AVOID CNS depressants |
What is the mechanism of action for Tegretol? | inhibiting sodium channels |
how is Tegretol metabolized? | liver. the longer you are on this drug, the shorter the half life |
Which drug requires that pts of Asian descent have genetic testing done before going on it? why? | Tegretol. because they are at increased risk for a deadly skin rash |
What are the 3 uses for Tegretol? | Epilepsy Bipolar Trigemiinal and glossopharyngeal neuralgias |
What are the adverse effects of Tegretol? | CNS: minimal Hematologic: bone marrow suppression -> leukopenia, anemia and thrombocytopenia neural tube defects can inhibit excretion of water skin rash!! |
What are the drug interactions of Tegretol? | phenytoin & phenobarbital: inductino of metabolism will be greather than with Tegretol alone grapefruit juice: inhibits the metabolism therefore increasing plasma levels. |
Which antiepileptic drug is the first line for all seizures? | valporic acid |
What labs should you monitor when your pt is on valporic acid? | ALT, AST, pancreatic amylase and lipase (because it poses threat to liver and pancreatic function |
s/s liver failure | jaundice, ascites, RUQ pain, dark urine, n/v, steatorrhea |
can you take valporic acid during pregnancy? | not recommended. teratogenic. category D |
what should your female patients be on when taking valporic acid (or any teratogenic drug)? | folic acid. |
What are the different uses for valporic acid? | seizures bipolar migraine |
what are the adverse effects of valporic acid? | MOST COMMON = GI (n/v, indigestion) hepatotoxicity pancreatitis teratogenic hyperammonemia rash weight gain hair loss tremor blood dyscarasias |
what are the s/s of hyperammonemia? | n/v/d, lethargy, altered LOC/cognition |
?what is the mechanism of action of Phenobarbital? | increases GABA effects |
what are some advantages to phenobarbital? | oral, effective, cheap, 1x per day, oral |
what are some side effects of phenobarbital? | lethargy, depression, learning impairment, drowsiness, somnolence |
what are some drug interactions of phenobarbital? | CNS depressant - AVOID others! barbiturate family |
Which are better tolerated, newer or older antiepileptic drugs? | newer |
what is the mechanism of action of Trileptal? | blocks sodium channels |
T/F: Trileptal is inactive until activated in the liver. | true |
what are some adverse effects of Trileptal? | diplopia, dizziness, nystagmus, headache, ataxia, hyponatremia, SKIN RXN! |
What is the mechanism of action for Lamictal? | blocks sodium and calcium channels decreases glutamate |
route of admin for Lamictal | oral |
what are some adverse effects of Lamictal? | life threatening rashes dizziness diplopia n/v headaches blurred vision |
what is the mechanism of action for Lyrica? | similar to neurontin |
T/F: Lyrica is a controlled substance | True: Category V (dt euphoria) |
what is the mechanism of action for Topamax? | GABA inhancer blocks Sodium, calcium, glutamate |
what is the metabolism and excretion of Topamax? | excreted by kidneys not metabolized |
what is the risk with Topamax? | can cause metabolic acidosis because kidneys excrete more bicarbonate causing acidosis |
what labs should you monitor when your pt is on Topamax? | Bicarbonate levels! |
what is the risk of antiepileptic drugs and pregnancy? | congenital heart defects most risk during first trimester |
What is the medical emergency during Status Epilepticus? | Airway mgmt acidosis |
what is used to stop a SE seizure? | benzodiazapines |
what are the major problems associated with SE? | massive hypoglycemia (dt energy expenditure) increased HR, BP, temp acidosis |