Phenytoin (Dilantin)

  1. Phenytoin Class
  2. Phenytoin
    Mechanism of action
    Promotes sodium efflux (out ward flow) from neurons, thereby stabilizing the neuron's threshold against excitibility caused by excess stimulation; in similar fashion, decreases abnormal ventricular automaticity and decreases the refactory period in the myocardial conduction system.
  3. Phenytoin
    Prophylaxis (the prevention of disease) and treatment of major motor seizures, digitalis-induced arrhythmias.
  4. Phenytoin
    Hypersensitivity, Bradycardia, second-and third-degree heart block.
  5. Phenytoin
    Adverse reactions
    Hypotension with too rapid IV push, heart block, arrhythmias, cardiovascular collapse, nausea, vomitting, ataxia(loss of coordination of the muscles), central nervous system depression, nystagmus(rapid, involuntary movement of the eyeball), pain at injection site, respiratory depression.
  6. Phenytoin
    Drug interactions
    Serum dilantin levels increased by: anticoagulants, tagamet, sulfonamides, salicylates. Metabolism increased by chronic alcohol use. Cardiac depressant effects increased by lidocaine, propranolol, and other beta blockers. Precipitation may occur when mixed with D5W. Incompatible with many solutions and medications.
  7. Phenytoin
    How supplied
    50 mg/mL in 2- and 5- mL ampules, 2-mL prefilled syringes. May be diluted in normal saline (NS) (1-10mg/mL); use in-line filter. Note: IV line should be flushed with 0.9% NS before and after drug administration.
  8. Phenytoin
    Dosage and administration
    • Adult: Seizures: 10-20 mg/kg slow IV, not to exceed 1g or rate of 50 mg/min. Arrhythmias: 50-100 mg (diluted) slow IV every 5-15 min PRN; maximum, 1g.
    • Pediatric: Seizures: 10-20 mg/kg slow IV (1-3 mg/kg/min). Arrhythmias: 5mg/kg slow IV; maximum, 1g.
  9. Phenytoin
    Duration of action
    • Onset: 20-30 minutes for seizure disorder.
    • Peak effect: 1-3 hours.
    • Duraton: 18-24 hours but as long as 15 days reported.
  10. Phenytoin
    Special considerations
    Pregnancy safety: not established. Carefully monitor vital signs. venous irritation may occur (use large stable vein).
Card Set
Phenytoin (Dilantin)
Paramedic pharmacology