Phenytoin may be administered IV directly into a large vein through a large gauge needle or IV catheter; however, it is preferred that phenytoin be administered via infusion pump either undiluted or diluted in NS to prevent exceeding the maximum infusion rate (monitor closely for extravasation during infusion). An in-line 0.22 to 0.55 micron filter is recommended for IV piggyback (IVPB) solutions due to the potential for precipitation of the solution.

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Neonates: Administer slowly, usual maximum recommended rate: 0.5 to 1 mg/kg/minute (AAP [Hegenbarth 2008]; Eichenwald 2017). Note: Although the manufacturer recommends a maximum rate: 1 to 3 mg/kg/minute, a lower maximum rate of infusion of 1 mg/kg/minute has been recommended (AAP [Hegenbarth 2008]; Hanhan 2001).

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Infants, Children, and Adolescents: Administer slowly, maximum recommended rate: 1 to 3 mg/kg/minute or maximum rate: 50 mg/minute, whichever is slower.

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Following IV administration, NS should be injected through the same needle or IV catheter to prevent irritation. Avoid IM use due to erratic absorption, pain on injection, and precipitation of drug at injection site.