IV PHENYTOIN NOMOGRAM

Patient Presents

Oral (PO load)

Proposed phenytoin loading

No phenytoin on board

First line agent:  lorazepam

New Onset Seizures

Actively Seizing

Not actively seizing with history of seizures on phenytoin.

History of seizures

Check the phenytoin level**.

Check the phenytoin level**. 

If not able to get phenytoin level, give partial phenytoin load using the IV or po route following the Flow A, B, or C.

Oral (po load)

NPO (IV load*)  If no IV access, give fosphenytoin IM.

Reload phenytoin level according to equation* and how much phenytoin needed.  Load the patient using the IV or  po route following the Flow A, B, or C.

Follow steps in Flow C.

Load phenytoin intravenously by using the equation * following the Flow A or  B.

Use equation*to find dose to get a phenytoin level of 10 mcg/mL.

NPO (IV load*)

IF no IV access, give fosphenytoin IM.

Can give phenytoin suspension, capsules, or chewable tablets.

 Flow C

Flow  A Flow B

Monitored Bed

Non-monitored Bed

Infuse using a 0.22 micron filter.  Flush IV line with NS before and after phenytoin administration

Infuse using a 0.22 micron filter.  Flush IV line with NS before and after phenytoin administration.

*Calculate loading dose.  Should be given in 3 doses:  400 mg, wait for two hours then give 300 mg, wait for two hours then give 300 mg, and then start maintenance dose after 24 hours.

IV load* at a rate of 50 mg/min on an infusion pump with a free flow lockout device into a large vein.  Use cardiac monitor and monitor HR, BP, RR, CNS, and IV site.

IV load* with dose of 15-20 mg/kg at a rate of 20 mg/min in 3 divided doses at 2 hour intervals on an infusion pump with a free flow lockout device into a large vein.  Monitor HR, BP, RR, CNS, and IV site.

Special Notes:

*To calculate loading dose: 

(Concentration Desired – Concentration Actual) x 0.7 x weight in kgs = dose in mg                              0.92

or

15-20mg/kg=dose in mg
 

**Total and free phenytoin levels should be drawn on patients with low albumin levels, elevated serum creatinine levels or patients receiving hemodialysis.

Consider a reduced phenytoin loading dose if patient has a history of renal or liver disease

Monitor at 5 & 15 minutes & at end of infusion for each bag.  If hypotension or bradycardia occur (any decrease from baseline), decrease the infusion rate by 50%, notify physician, and monitor q 5 minutes X 3 &/or until stable.

Monitor at 5, 15, & every 30 minutes.  If hypotension or bradycardia occur (any decrease from baseline), decrease the infusion rate by 50% , notify physician, and monitor q 5 minutes X 3 &/or until stable.

8/2003