II. Indications

  1. Adjunctive management of Partial Seizures
  2. Add to primary antiepileptic regimens
    1. Carbamazepine
    2. Phenytoin
    3. Valproate
  3. Other potential uses currently being researched
    1. Myoclonic Seizures
    2. Infantile Spasm
    3. Atypical Absence Seizure
    4. Generalized Tonic Clonic Seizures

III. Pharmacology

  1. Weak carbonic anhydrase inhibitor
  2. Sulfonamide that blocks Sodium and calcium channels
    1. Increases Dopaminergic transmission
    2. Increases serotonergic transmission
  3. Metabolized by CYP3A4
  4. Half-Life: 60 hours

IV. Drug Interactions

  1. Increased Zonisamide clearance with CYP3A4 inducers
    1. Phenytoin
    2. Carbamazepine
    3. Phenobarbital
  2. Concurrent carbonic anhydrase inhibitor (Topamax)
    1. Increased Nephrolithiasis risk

V. Adverse effects

  1. Dizziness
  2. Ataxia
  3. Somnolence
  4. Nausea
  5. Anorexia
  6. Abdominal Pain
  7. Insomnia
  8. Impaired cognition
    1. Confusion
    2. Decreased concentration
    3. Speech problems
  9. Psychosis
  10. Nephrolithiasis
  11. Rash
  12. Stevens Johnson Syndrome
  13. Toxic Epidermal Necrolysis
  14. Childhood Adverse Effects
    1. Oligohydrosis
    2. Hyperthermia (and Heat Stroke)

VI. Contraindications

  1. Sulfonamide Allergy
  2. Pregnancy (Teratogenic in animals)

VII. Dosing: Adults

  1. Initial: 100 mg PO qd
  2. Increase: 100 mg every two weeks as needed
  3. Maximum: 600 mg/day divided qd-bid
  4. Caution: Increase more slowly in Renal Insufficiency

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Cost: Medications

zonisamide (on 5/17/2017 at Medicaid.Gov Survey of pharmacy drug pricing)
ZONISAMIDE 100 MG CAPSULE Generic $0.15 each
ZONISAMIDE 25 MG CAPSULE Generic $0.11 each
ZONISAMIDE 50 MG CAPSULE Generic $0.15 each
zonegran (on 11/23/2016 at Medicaid.Gov Survey of pharmacy drug pricing)
ZONEGRAN 100 MG CAPSULE Generic $0.15 each
ZONEGRAN 25 MG CAPSULE Generic $0.11 each

Ontology: zonisamide (C0078844)

Definition (NCI) A sulfonamide derivative with an anticonvulsant property. The exact mechanism of action remains to be elucidated. Zonisamide appears to block sodium and calcium channels, thereby stabilizing neuronal membranes and suppressing neuronal hyper-synchronization. Although zonisamide shows affinity for the gamma-aminobutyric acid (GABA)/benzodiazepine receptor ionophore complex, it does not potentiate the synaptic activity of GABA. In addition, this agent also facilitates both dopaminergic and serotonergic neurotransmission.
Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C022189
SnomedCT 398762003, 125693002
LNC LP28438-7, MTHU013979
English 1,2-benzisoxazole-3-methanesulfonamide, 3-sulfamoylmethyl-1,2-benzisoxazole, 1,2-Benzisoxazole-3-methanesulfonamide, zonisamide (medication), ZONISAMIDE, zonisamide [Chemical/Ingredient], zonisamide, Zonisamide (product), Zonisamide (substance), Zonisamide
Spanish zonisamida (producto), zonisamida (sustancia), zonisamida

Ontology: Zonegran (C0876224)

Concepts Pharmacologic Substance (T121) , Organic Chemical (T109)
MSH C022189
English Zonegran, zonegran, Elan brand of zonisamide