IV PHENYTOIN

• Status epilepticus for patients not taking maintenance phenytoin
• • if on maintenance phenytoin, contact neurology SpR to discuss reduced dose of IV phenytoin or use of levetiracetam. See Levetiracetam IV guideline

• Phenytoin sodium injection 50 mg/mL in 5 mL (250 mg) ampoules

• Sodium chloride 0.9% only

• Administer slowly into a large vein
• if phenytoin is given too rapidly, hypotension, cardiac arrhythmias, impaired cardiac conduction, CNS depression or respiratory arrest can occur

Check infusion site regularly

• Soft tissue irritation and inflammation can occur with or without extravasation
• varies from slight tenderness to extensive necrosis and sloughing, requiring amputation in rare instances
• Ensure extravasation does not occur

Monitor ECG and BP

• Monitor all patients with continuous ECG and BP throughout the infusion 

• Phenytoin 20 mg/kg up to a maximum of 2 g by slow IV administration into a large vein through an in-line filter (0.22–0.5 micron) no faster than 50 mg/min

IV infusion of undiluted phenytoin (50 mg/mL) via syringe pump

• Preferred method of delivery at dose of 20mg/kg

How to give

• Use a 0.22–0.50 micron in-line filter. Obtain from supplies department
• Draw up required volume of phenytoin sodium injection 50 mg/mL in syringe used by syringe pump
• need more than one ampoule of Phenytoin sodium injection 50 mg/mL in 5 mL (250 mg)
• Before phenytoin administration, flush cannula with sodium chloride 0.9%
• Administer over at least 30 min via syringe pump set at required rate
• After phenytoin administration, flush cannula with sodium chloride 0.9%

IV infusion of diluted phenytoin

• Use if a syringe pump is not available
• Phenytoin sodium injection can be diluted in 100 mL sodium chloride 0.9% to a maximum concentration of 10 mg/mL (i.e. max 1000 mg in 100 mL)
• if dose exceeds 1000 mg, divide total dose between 2 x 100 mL bags and run concurrently

How to give

• Check that solution is free of haziness or precipitation
• Use a 0.22–0.50 micron in-line filter. Obtain from supplies department
• Before phenytoin administration, flush cannula with sodium chloride 0.9%
• Start administration immediately after dilution to ensure infusion is completed within 1 hr of preparation
• Follow selected infusion rates to ensure not administered faster than 50 mg/min
• After phenytoin administration, flush cannula with sodium chloride 0.9% 

• In patients given an IV loading dose, measure phenytoin concentration within 2–3 days of initiating therapy
• obtain a second phenytoin concentration in another 3–5 days
• adjust subsequent doses of phenytoin
• If the plasma phenytoin concentrations have not changed over a 3–5 day period, the monitoring interval can usually be increased to once weekly in the acute clinical setting