Pharm Test 4: Anticonvulsants

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Pharm Test 4: Anticonvulsants
2013-02-17 15:02:35
Pharm Test Anticonvulsants Antiseizure

Pharm Test 4 Anticonvulsants/antiseizure
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  1. Any abnormal neuronal discharge in the brain
  2. Chronic, recurrent seizures

    *Epilepsy is a disease, seizure is a symptom
  3. Consciousness preserved; manifested variously as convulsive jerking, paresthesia, psychic symptoms and autonomic dysfunction
    Partial seizure, simple
  4. Impaired consciousness that is preceded, accompanied, or followed by psychiatric symptoms.
    Partial seizures, complex
  5. Involve both hemispheres of the brain
    Generalized seizures
  6. 2 Types of Generalized Seizures
    • Absence (juvenile)
    • Myoclonic
  7. Brief altered state of conscious and staring episodes
    Absence (Juvenile) seizure
  8. Large amplitude of T-type Ca2+ currents in thalamus
    Generation of thalamic oscillatory activity (3 Hz spike and wave rhythms)
    Absence (Juvenile) seizure
  9. Drug of choice for Absence Seizures
    • Ethosuxamide OR
    • Valproic Acid- esp. useful in patients who have concommitant generalized tonic-clonic or myoclonic seizures
  10. Can be used to treat Absence seizures, but can cause sedation and toleranze
  11. Brief contraction of muscles
    Myoclonic seizure
  12. Drug of choice for Myoclonic Seizures
    • Levetiracetam OR
    • Zonisamide
  13. Tonic-Clonic Seizure Phases
    • Tonic
    • Clonic
    • Postictal
  14. 3 things that happen in tonic phase of tonic clonic seizure
    • Loud moan, secretions, and cyanosis
    • Increased sympathetic tone
  15. Clonic phase of seizure is characterized by
  16. Postictal phase of seizures characterized by
    • Unresponsiveness, muscular flaccidity
    • Excessive salivation
    • Bladder/bowel incontinence
  17. Barbituates:
    Name 2
    • Phenobarbital, Primidone
    • Increases duration of GABA channel opening (Increases Cl- conductance at GABAA channel)
    • Epilepsy (Status epilepticus)
  18. Benzodiazepines:
    Name 2 long-acting
    Treats what type of seizure?
    • Diazepam, Lorazepam
    • Increases frequency of GABA channel opening (Increases Cl- conductance at GABAA channel)
    • Tonic Clonic Seizures
  19. Both barbituates and benzodiazepines can have what adverse effects
    Respiratory depression
  20. Name 2 Hydantoins
    • Phenytoin- bound to plasma protein
    • Fosphenytoin- water-soluble, converted to phenytoin by phosphatases in the liver
  21. Phenytoin:  MoA
    Blocks voltage-gated Na+ channels in neuronal membranes -> prolonged inactivation of Na+ channel (and thus refractory period of the neuron)

    *Carbamazepine, Lamotrigine, and Zonisamide also do this
  22. Phenytoin:  Treats
    Partial & Tonic/Clonic Seizures (does NOT treat Absence Seizures)
  23. Drug interaction:  Degrades oral contraceptives -> unwanted pregnancy
  24. Fetal Hydantoin Syndrome (Phenytoin teratogenicity)
    • Cleft lip, palate
    • Congenital Heart Disease
    • Skeletal malformation
    • Impaired intellectual development
  25. Phenytoin interaction w/ Carbamazepine, sulfonamides, valproic acid
    These drugs displace phenytoin from the plasma membrane proteins -> Increased free phenytoin in plasma
  26. Phenytoin interaction w/ Phenobarbital and Rifampin
    Increases metabolism of Phenytoin in the liver (CYP inducers) -> need to increase dosage of phenytoin
  27. Phenytoin interaction w/ Cimetidine and Isoniazid
    Decrease metabolism of Phenytoin in the liver (CYP inhibitors) -> decrease amnt of Phenytoin administered
  28. Phenytoin's effects on other antiepileptic drugs
    Phenytoin induces hepatic drug metabolism -> decreased effects of other antiepileptic drugs including carbamazepine, clonazepam, and lamotrigine
  29. 2 Phenytoin toxicities
    • Osteomalacia w/ hypocalcemia and increased alkaline phosphatase activity
    • Gingival hyperplasia
    • Peripheral Neuropathy (diminished deep tendon relfexes in the lower extremities)

    *Small increase can have drastic effects
  30. Name 4 drugs that block the voltage-gated Na+ channels and prolonged the inactivated state of the neuron
    • Phenytoin
    • Carbamazepine
    • Lamotrigine
    • Zonisamide

    Please Call LorenZo
  31. Carbamazepine treats
    • Partial AND Tonic-Clonic Seizures
    • Bipolar pts (where Li isn't effective)
    • Trigeminal and Glossopharyngeal nerve neuralgias
  32. Drug that increases ADH (anti-diuretic hormone)
  33. CYP effects:
    Valproic Acid?
    • P= inducer
    • C= inducer
    • V= inhibitor
  34. Carbamazepine toxicities
    • CYP inducer
    • Hematological abnormalities
  35. Inhibits low-threshold (T-type) Ca2+ currents (in thalamic neurons)
  36. Ethosuxamide:  MoA
    Inhibits low-threshold (T-type) Ca2+ currents (in thalamic neurons)
  37. Ethosuxamide treats
    Generalized absence seizures
  38. Valproic Acid treats
    Partial and primary generalized epilepsies
  39. Irreversibly inactivates GABA-T (enzyme that terminates GABA action) -> prolonged inhibitory action of GABA
  40. Vigabatrin: MoA
    Irreversibly inactivates GABA-T (enzyme that terminates GABA action) -> prolonged inhibitory action of GABA
  41. Vigabatrin treats
    • Partial seizures
    • Infantile spasms
  42. Long-term use of Vigabatrin can result in
    Irreversible visual field defects
  43. Metabolized by UGT
  44. Lamotrigine is metabolized by ___ and therefore interacts with

  45. Drug that can cause Stevens-Johnson Syndrome, TEN
  46. Drug that inhibits GAT-1 (The drug is a GABA reuptake inhibitor)
  47. Tiagabine: MoA
    Inhibits GAT-1 (a GABA reuptake transporter)
  48. Structural analogue of GABA that stimulates GABA release indirectly

    *It also binds the alpha2delta subunit of neuronal voltage-gated Ca2+ channels -> decreased Ca2+ entry
  49. Gabapentin interaction w/ other anticonvulsants
    Does NOT interact w/ other anticonvulsants, excreted unmetabolized in the urine
  50. GABApentin treats
    Adjunct therapy for partial seizures
  51. Inhibits voltage gated Na+ and Ca2+ channels -> increased GABA release
    Topiramate (GABA to the top!)
  52. Topiramate complication
    Renal stone formation
  53. Renal stone formation
  54. Zonisamide complicatoins
    • Renal stone formation (like Topiramate)
    • Oligohydrosis
  55. Zonisamide metabolism
    Metabolized by CYPs
  56. Drugs of Choice:  Generalized Tonic-Clonic Seizure
    • Valproic Acid
    • Carbamazepine
    • Phenytoin
  57. Drugs of Choice:  Partial Seizures
    • Carbamazepine (or oxcarbazepine)
    • Lamotrigine
    • Phenytoin
  58. Drugs of Choice: Absence Seizures
    • Ethosuxamide
    • Valproic acid (esp. w/ concommitant tonic-clonic or myoclonic seizures)
  59. Drugs of Choice: Myoclonic & Atypical Absence Syndromes
    Valproic Acid (Lamotrigine can be used as adjunctive therapy; or you can just use V as monotherapy)
  60. Drugs of Choice:  Status Epilepticus
    • IV Diazepam or Lorazepam (terminate attacks, short-term control)
    • IV Phenytoin or Fosphenytoin (long-term control)
  61. Tx cross-over:  Valproic Acid
    • Generalized tonic-clonic seizures
    • Absence seizures + tonic-clonic/myoclonic
    • Myoclonic and Atypical Absence Syndromes
    • Mania (first line tx)
  62. Tx cross-over:  Carbamazepine
    • Generalized tonic-clonic seizures
    • Partial seizures
    • Bipolar disorder
    • Trigeminal neuralgia
  63. Tx cross-over:  Lamotrigine
    • Partial Seizures
    • Bipolar Disorder
  64. Tx cross-over:  Gabapentin, Topiramate
    • Seizures
    • Migraine
  65. Teratogenicity:  Valproic Acid
    Neural tube defects (spina bifida)
  66. Teratogenicity:  Carbamazepine
    • Craniofacial anomalies
    • Spina bifida
  67. Teratogenicity:  Phenytoin
    Fetal Hydantoin Syndrome (cleft lip/palate, congenital heart disease, impaired intellectual development)
  68. Anticonvulsant OD causes
    CNS depression (respiratory depression)

    *Manage w/ supportive care
  69. Benzodiazepine OD can be treated w/

    Benzos= F (Frequency, flumazenil)
  70. Ethosuximide can NOT treat
    • Partial seizures
    • Generalized tonic-clonic seizure states
  71. Weight gain is common with
    Valproic acid
  72. Withdrawal of drugs from what kind of seizures is the easiest?
    What drugs produce the most severe withdrawals?
    Absence seizures is easiest

    Benzos and barbituates= severe withdrawal