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19 Cards in this Set
- Front
- Back
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How Antiepileptic Drugs Work
sodium influx suppression |
-sodium influx into neuronal cells propagates an action potential
-drugs such as Phenytoin, Carbamazepine, & Valproic Acid reversibly bind to sodium channels & prolong their inactivated state |
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How Antiepileptic Drugs Work
GABA potentiation |
-GABA is primary inhibitory neurotransmitter of CNS
-mimicked – Barbiturates -enhanced – Benzodiazepines -increased release -reuptake inhibition -degradation inhibition |
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How Antiepileptic Drugs Work
calcium influx suppression |
-Calcium influx into axon terminals promotes neurotransmitter release into synaptic cleft
-drugs eg Valproic Acid block calcium channels |
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How Antiepileptic Drugs Work
antagonism of glutamate |
-is primary excitatory neurotransmitter of CNS
-acts on NMDA (N-methyl-D-aspartate) Receptors & AMP (alpha-amino-3-hydroxy-5-methyl-4- isoxazole propionic acid) |
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Phenytoin
trade |
Phenytoin
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Phenytoin
USES |
-Tonic-clonic seizures
-simple partial seizures -complex partial seizures -NOT absence seizures |
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Phenytoin
Pharmacokinetics |
-absorption: dependent on formulation
-metabolism: limited liver capacity -half-life: dependent upon liver function |
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Phenytoin
Drug Interactions |
-induces production of hepatic drug metabolizing enzymes. ↓ effects of oral contraceptives, warfarin, & glucocorticoids
-diazepam & alcohol (acute) ↑plasma levels of phenytoin -carbamazepine, phenobarbital & alcohol (chronic) can ↓levels of phenytoin -any CNS depressant |
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Phenytoin
Dose |
Prep 50mg/ml Vial
Dose 10-20mg/kg at 30-40mg/min Admin Not exceed 50mg/min – CVS collapse Not mix with other infusions - precipitate |
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Phenytoin
MAO |
-selective inhibition) Slows recovery of Na+ channels
-Limited to hyperactive neurons. |
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Phenytoin
Adverse Effects |
-CNS: Nystagmus, sedation, ataxia, diplopia, cognitive
-gingival hyperplasia -rash -teratogen -CVS: Dysrhythmia’s, hypotension |
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Phenobarbital
trade type |
Luminal©
anticonvulsant |
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Phenobarbital
USES |
- simple partial seizures
-complex partial seizures -tonic-clonic seizures -NOT absence seizures -sleep agent |
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Phenobarbital
Drug Interaction |
-induces production of hepatic drug metabolizing enzymes
-CNS depressants |
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Phenobarbital
does |
Prep 120mg/ml Ampule
Dose 10-20mg/kg at 25 – 60mg/min Admin Slowly – CNS depression |
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Phenobarbital
EFFECTS |
-Able to suppress seizures without causing sedation.
-Supresses them by potentiating GABA. -(MOA: potentiates GABA. The exception!) |
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Phenobarbital
ADVERSE: |
Drowsiness
Sedation Irritability Confusion Withdrawal Physical dependence Teratogen |
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Phenobarbital
CONTRA: |
liver failure
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Phenobarbital
CAUTION: |
• asthma
• CNS depressants • habit forming • withdrawal • MAOIs Nystagmus Ataxia CNS/Resp ↓ |
