Phenytoin

Pharmaceutics

Contains

• propylene glycol

Clinical

Dosage

• Loading dose = 15 mg/kg
• Subsequent infusion = 3 to 4 mg/kg/day

Example

In a 70kg man

• Loading dose ≈ 1000mg
  ... over at least 20 min

Injection safety

# Maximum infusion rate:

• In adults: Slower than 50 mg/min
  - If cardiac counditions, slower than 25 mg/min
• Neonate = 1 to 3 mg/kg/min

# Inject into large veins only

# Consider diluting into 100mL of normal saline

• Do Not mix with glucose
• Use an inline filter (0.22 micron)
  - Must be used if phenytoin diluted

Side effects

# Very high pH (alkaline)

• Can cause direct tissue injury
  ... with or without extravasation
• Can cause Purple Glove Syndrome

# Hypotension

# Cardiotoxicity

• Arrhythmia