Antiseizure Drugs
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- Antiseizure drugs are used for what type of pt's
- Those with febrile seizures or seizures due to acute illness (meningitis)
- Define epilepsy
- Means "to seize upon". Applied to those with chronic seizures
- What 4 things are abnormal in seizures?
- Sensory, motor (convulsions), autonomic, and psychic activity
- Under partial seizures, describe the fx's of a simple partial seizure?
- No loss of consciousness, focal motor, sensory, or speech disturbances
- Describe a complex partial seizure?
- Has impaired consciousness, dreamy disaffected state, with or w/o automatisms
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Generalized seizures involve both ____?
State the difference b/t a grandmal and petit mal seizure? -
GM/tonic clonic: sensory aura, gen. convulsions of musculature, LOC
PM/absence seizures: LOC (30sec), immobility, vacant look, children 4-12yrs - What is a third type of gen. seizure? Describe it?
- myoclonic? Myoclonic jerks, loss of muscle tone, falling
- What could be the etiology of various seizures?
- idiopathic, brain injury, congenital malformation, w/drawal from antidepressants, neoplasia, genetics, hyperthermia (kids), kindling from prior shock
- An antiseizure drug should perform at least one of the following things?
- Enhance GABAergic xmission(inhibitory)diminute glutamatergic xmission(excitatory), or modify ionic conduction
- What is a neurons RMP? What is the fxn of depolarization and hyperpolarization?
- -70mV. 1) Na+ enters cell, and moves potential to a pos. value 2) K+ leaves the cell, or Cl- enters moving the potential to a neg value where the cell has less potential to fire.
- Glutamate binding induces what process?
- Depolarization by opening Na+ channels.
- How does the binding of GABA to the GABA,A receptor affect the cell?
- Opens a Cl- channel, hyperpolarization.
- How do Na+ channels close after depolarization?
- The spontaneously inactivate
- What drug may control Ca+ currents in absence seizures? In what way?
- Ethosuximide. By the reduction of currents.
- What 3 changes may initiate neuron excitability?
- Abnormal ionic channels, receptors, or the extracellular environment.
- Name the drugs and their categories which slow Na+ channel recovery from inactivation?
- Phenytoin (Hydantoin), Carbamazepine (Iminostilbenes), Valproic acid (Carboxylic acids), Lamotrigine, & Topiramate
- These drugs may allow more Cl- ions to enter a neuron, and block glutamate receptors?
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Phenobarbitol, Primodone (barbituates)
Diazepam, Clonazepam (benzodiazepines) - What two anticonvulsants is primodone metabolized to?
- Phenobarbitol, & Phenylethylmalonamide
- What neurons are thought to be resposible for absence seizures?
- Thalamic neurons.
- These drugs reduce the current through Ca+ channels in thalamic neurons?
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Ethosuximide (Succinimides)
Valproic Acid (Carboxylic acids - These drugs inhibit the metabolism of "GABA"
- Vigabatrin, Gabapentin, & Tiagabine
- What is the MOA of Vigabatrin?
- Irreversible inhibitor of GABA-transaminase
- What is the MOA of Gabapentin?
- Promotes nonvesicular release of GABA or inhibits its uptake
- What is the MOA of Tiagabine?
- Inhibits GABA uptake
- O.k. Smarty pants! Name the drugs that work at the GABA receptor, transporter, nonvesicular release, transaminase inhibitor
- 1) Benzodiazepines, Barbituates 2) Tiagabine, Gabapentin, Vigaba"trin"
- The new drug Zonisamide has what actions? What is its side effect?
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Blocks Na+ channels, reduces Ca+ channel activity, inc. GABA release, blocks K+/glutamate-mediated excitation.
Weight loss - This drug has similar actions to Zonisamide but may treat bipolar disorder and EtOH consumption?
- Topiramate
- These 2 drugs "C"an "G"o and treat simple partial seizures
- Carbamezepine, and Gabapentin
- This drug may treat complex partial and all types of generalized seizures
- Valproic acid
- What 2 drugs may aggravate absence seizures? ("Ph"ina "C"an't)
- Carbamezapine, and Phenytoin
- These repeated seizures are lifethreatening and require heart, lung, and metabolic management. What are they and what is used to treat them?
- Status Epilepticus. Diazepam, Phenytoin, and Phenobarbital if no success.
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What are some of the many side effects of antiseizure drugs?
(NoVie HAS A RAW Rash) - N/V, rash, nystagmus, disturbed vision, ataxia, sedation, aplastic anemia, hepatoxicity, resp. depression w/ overdose, w/drawal effects
- Why is the dosing of phenytoin so important?
- As the dosage increases, the hydroxylation system becomes saturated so that more doses produce large increases in plasma concentration.
- What drugs may positively effect the metabolism of phenytoin?
- carbamezepine, and phenobarbitol
- These drugs may negatively effect the metabolism of carbamezepine?
- Erythromycin, Isoniazid, and Propoxyphene
- These are some side effects of phenytoin?
- N/V, CNS depression, confusion, inhibition of ADH, gingival hyperplasia, hirsutism, megaloblastic anemia
- Phenytoin may also have this effect?
- Antiarrhythmic
- What are the risks for expectant mothers taking phenytoin?
- "Fetal hydantoin syndrome" - cleft lip, cleft palate, congenital heart disease, growth and mental deficiency
- What drug has been implicated to cause spina bifida?
- Valproate
- These 3 antiseizure drugs may treat mania?
- carbamazepine, gabapentin, valproate
- These 2 drugs may act as mood stabilizers?
- Topiramate and carbamazepine
- This drugs may tx Parkinson's disease
- Gabapentin
- These 2 drugs may treat migraines?
- Valproate, and Zonisamide
- These two drugs may treat neuropathic pain?
- Gabapentin, and Zonisamide