DRUG SUPPLIED DOSE COMMENTS
PHENYTOIN (Paeds)
(Dilantin)

Mechanism of action:

Anticonvulsant.


Ref: 44, 336, 366, 557



Last update: 2022-09-09		 injection: 50 mg/mL (contains propylene glycol diluent)

tablet: 50 mg (chewable)

capsule: 30 mg, 100 mg

suspension: 6 mg/mL, 25 mg/mL - AVOID USING DUE TO INCONSISTENCY OF DOSE

Sodium salt: capsules and injection.
Free acid: chewtab and suspension.		 Status Epilepticus:
IV loading dose:
20 mg/kg/dose IV (max: 1500 mg/dose).
May give additional load of 5-10 mg/kg/dose after 10 mins if not resolved

Seizures:
PO loading dose (if new on phenytoin): 6.7 mg/kg/dose x 3 doses administered every 2-4 hours to maximize absorption (total 20 mg/kg).

Initial Maintenance for Seizure Disorder:
Infants, Children, and Adolescents:
2.5 mg/kg/dose PO/IV Q12H or
1.7 mg/kg/dose PO/IV Q8H (Max: 300 mg/24 hrs)
(Usual range is 4-10 mg/kg/24 hours according to serum monitoring and clinical response.  Neonates and infants may require Q8H dosing up to 10 mg/kg/24 hr)
 Hazardous drug. Refer to Hazardous Drug Handling Policy.

Avoid if allergy to aromatic hydrocarbons (carbamazepine, phenobarbital).

At higher serum concentration, small dose increases can result in disproportionately high serum levels.

Highly protein-bound. Consider free phenytoin levels in hypoalbuminemia.

Max IV administration rate: 1 mg/kg/min or 50 mg/min in patients > 50 kg.

IV adverse effects: bradycardia, hypotension, cardiac arrhythmia, cardiovascular collapse and thrombophlebitis, Stevens-Johnson syndrome. See Parenteral Manual.

For tube-fed patients: crushed chewable tablets administered via tube preferred over liquid to achieve a more consistent dose. Dose and frequency should accommodate available tablet size.

Enteral feeds may decrease phenytoin absorption. Phenytoin doses should be separated from enteral feeds by 1-2 hours.

Target serum concentration: 40-80 umol/L.

Refer to Therapeutic Drug Monitoring in References and Supplementary (white pages in hard copy)


Standard Prescription:

LOADING DOSE:
phenytoin __mg IV x 1 loading dose (__mg/kg/dose)
phenytoin __mg PO Q__H x 3 doses (total loading dose __mg/kg)

MAINTENANCE DOSE:
phenytoin __mg IV/PO Q__H (__mg/kg/24 hr)