Term
| What are our four strategies for treating seizures? |
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Definition
1. **Blocking Na+ channels
2. GABA facilitation (barbiturates and BZs)
3. Antagonize glutamate receptors (AMPA & NMDA)
4. *Block Ca2+ influx through *type-T channels in thalamus |
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Term
| What are the three major drugs and what type are they? |
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Definition
1. Carbamazepine & phenytoin are Na+ blockers
2. Valproic acid is a Ca2+ blocker |
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Term
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Definition
-Partial; one area (awake)
-General, tonic-clonic; whole body thrashes (unconscious)
-General, absence; "unplugged" (unconscious)
-Status epilepticus; prolonged (>30) and life threatening
-Can be from *abrupt treatment withdrawal |
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Term
| What are the two Na+ blockers and mechanism? What can they treat? What side effects do they have in common (5)? |
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Definition
-Carbamazepine & phenytoin both block Na+ channels in their inactive state (can only stop propagation, not initiation)
-Treat all seizure states except absence
Common side effects;
1. CNS depression (dose dependent drowsiness); must worry about **additive effects
2. Osteomalacia (↓Vit D), and hyper/hypocalcemia
3. Megaloblastic anemia (↓folate from ↓GI conjugases)
4. Teratogenicity (clefts & spina bifida for carbamazepine)
5. Aplastic anemia from hapten caused hypersensitivity (requires use of CBCs regularly) |
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Term
| What are the unique side effects for phenytoin and carbamazepine? |
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Definition
Phenytoin;
-Gingival hyperplasia; can lead to infection & endocarditis
-Hirsutism; hair female
-**[both only seen with this drug]
Carbamazepine;
-Exfoliative dermatitis; life threatening rash (hypersen.)
-**↑ADH secretion; →dilutional hyponatremia→ edema→ ↑ICP→ herniation |
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Term
| What is special about the kinetics for phenytoin and carbamazepine? |
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Definition
-Phenytoin has **zero order elimination causing non-linear kinetics with a smaller window of efficacy (see 147)
-Both *induce cytochrome P450 (porphyria's a concern)
-Carbamazepine is actually eliminated by P450 also (tolerance will be seen) |
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Term
| What do phenytoin and carbamazepine treat? |
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Definition
-All seizure states (except absence) for both
-Carbamazepine can also treat; **trigeminal neuralgia (DOC), and biopolar disorder (manic portion) |
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Term
| What is the important Ca2+ channel blocker and it's mechanism? |
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Definition
-*Valproic acid inhibits **T-type Ca2+ channels in their inactive state (similar to phenytoin mech.)
-Also inhibits **GABA transaminase→ ↑GABA→ **BZ-like effects (CNS depression)
-Also it **inhibits P450 (others induce); less metabolism |
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Term
| What does valproic acid treat and its side effects? What is |
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Definition
Treats;
-**ALL seizure states
-Also migraines and bipolar mania
-(sim. to carbamazepine)
Side effects;
-Also teratogenic (spina bifida), but rest are diff.
1. Hepatotoxic (metabolites)
2. Thrombocytopenia (CBCs needed)
3. Pancreatitis
4. Alopecia (compair to phenytoin with hirsutism) |
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Term
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Definition
| -Another Ca2+ channel blocker used only for absence seizures |
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Term
| What is the anticonvulsant used during pregnancy? What about the P450 interactions is relevant to pregnancy? |
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Definition
-Phenobarbitol (barbiturate) because of it's higher plasma protein binding; less free fraction to cross placenta
-Most of the anticonvulsants induce P450 (except valproic acid) which metabolizes BC drugs→ pregnancy (while on a teratogenic drug!) |
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Term
| What is Stevens-Johnson syndrome? |
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Definition
-A type of exfoliative dermatitis which often leads to death
-Carbamazepine is the one that causes it |
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Term
| Note; see notes for additional info and *memory tools |
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Definition
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