UMEM Educational Pearls

Category: Toxicology

Title: Phenytoin: PO vs IV load

Keywords: phenytoin, anticonvulsants, loading dose (PubMed Search)

Posted: 12/27/2007 by Fermin Barrueto, MD (Updated: 7/10/2020)
Click here to contact Fermin Barrueto, MD

                                      Phenytoin po      Phenytoin IV       Fosphenytoin

Time to therapeutic       6.4 hrs                  1.7 hrs                 1.3 hrs

Adverse Events              0.69/pt                   1.86/pt                 1.87/pt

Cost                                   $2.83                   $88.50                $224.09
 
(Swadron et al. Ann Emerg 2002)

Also to take into account  is that the adverse events with IV phenytoin include soft-tissue necrosis if there is extravasation of infusion. The cardiotoxicity seen with phenytoin and fosphenytoin is largely due to the propylene glycol diluent and thus not seen with oral loading or even in oral overdosing.

You decide, at least you have the data to properly evaluate the risk:benefit ratio.