pharm (anticonvulsant)

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pharm (anticonvulsant)
2012-06-01 23:50:36
last lec

anticonvulsant, antiseizure, antiparkinson
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  1. types of seizures?
    • general
    • 1) nonconvulsive seizure: staring; stop whatever they are doing
    • 2) convulsive seizure: loss of consciousness

    • partial
    • 1) simple: consciousness unaltered
    • 2) complex: consciousness impaired or lost
  2. general mechanism of action of anticonvulsant
    • 1) limit the sustained repetitive firing of neuron, by promoting the inactivated state of the sodium channel
    • when Na are inactivated, no transport of Na, no depolarization --> neurons wont fire; seizure prevented
    • 2) enhance GABA mediated synaptic inhibition. some agents block T-type calcium channel
  3. anything that enhance GABA - prevent seizures!
    ex. barbiturates**phenobarbitol
  4. phenobarbital
  5. enhance GABA binding, delaying closure of chloride channels
  6. benzodiezapines

    increase the frequency of opening chloride channel of GABA
  7. phenytonin (dilantin) hydantoins

    • Uses:
    • Generalized tonic-clonic seizures and partial seizures with complex symptoms. Oldest nonsedative antiseizure drug.

    • mechanism:
    • slow rate of recovery of Na channel from inactivation. reducing Na current and neuronal firing

    adverse effect: gingival hyperplasia!!!!!

    • pharmacokinetics:
    • absorption is slow but complete and occure mainly in duodenum
    • can displace thyroxin, salicylic acid, valproic acid from albumin
    • zero-order kinetics - high dose required for control seizure
  8. what is the adverse effect of phenytoin?
    • gingival hyperplasia 20% of pt
    • most common menifestation of phenytoin toxicity
  9. but only where the teeth are present! not in toothless area
  10. drug interaction of phenytoin
    with oral contraceptive - unplanned pregnancy

    because phenytoin induce p450 which degrades oral contraceptives
  11. carbamazepine (tegretol)

    also used to treat trigeminal neuralgia and bipolar disorders

    not gonna be on this exam but maybe for NB
  12. ethosuximide (zaronti)

    • blocks T type calcium current in thalamic neuron
  13. valproic acid (depakene) divalproex

    fatty carboxylic acids with antiseizure properties

    used to terat all types of epilepsy and cause fatal hepatitis
  14. tipiramate
  15. felbamate
  16. lamotrigine
  17. tiagabine

    inhibit GABA transporter GAT-1
  18. zonisamide

    • inhibit carbonic anhydrase and may cause renal calculi
    • mechanism of action
    • blockade of Na+ and voltage gated Ca++ channels
  19. levetiracetam
    Anticonvulsants (partial seizure)
  20. diazepam

    to tx status epilepticus
  21. 4 main clinical features of parkinsons
    • 1) bradykinesia (slowness of and poor movement)
    • 2) muscular rigidity
    • 3) resting tremor (abates during voluntary movement)
    • 4) postural instability leading to disturbance of gait and falling

    sometimes they ust freeze and someone has to come and help them
  22. hallmark of parkinsons dz
    they pathologic hallmark of PD is a loss of pigmented dopaminergic neurons of the substantia nigra pars compacta, with the appearance of intercellular inclusions called lewy bodies
  23. D1 receptors
    synthesize cAMP
  24. D2 receptor
    inhibit formation of cAMP
  25. Levodopa is given with what?
  26. what is the antiparkinson agent?
    levodopa and carbidopa TOGETHER!
  27. sinemet?
    combination of levodopa and carbidopa
  28. carbidopa?
    peripherally acting inhibitor of aromatic L-amino acid decarboxylase that do not penetrate well into CNS
  29. major side effect of levodopa?
    • orthostatic hypotension
    • (bc dopamine can act as a vasodilator)
  30. what agents cause hypertensive crisis with levodopa?
    nonspecific MAO inhibitor (phenelzine and tranylcypromine)

    wine and cheese are not good for people on MAO bc of high content of tyromine which can cause release of these catecholamines
  31. some fact: duration of beneficial effects of levodopa may exceed the plasma lifetime of the drug, suggesting that the nigrostriatal dopamine system retains some capacity to store and release dopamine
    • buffereing capacity - capacity to store levodopa
    • sometimes on someitmes off you dont know
  32. dopamine receptor agonists
    • bromocriptine
    • pergolide
    • ropinirole
    • pramipexole
  33. Catechol-O-methyltransferase (COMT) inhibitors
    • tolcapone
    • entacapone
  34. MAO-B inhibitors
    • responsible for most oxidative metabolism of dopamine in the brain
    • present in periphery
    • selegline is selective for MAO-B
  35. selegline
    selective inhibitor of MAO-B