Phenytoin

PHARMACOLOGY

Onset of action: 0.5-1 h IV
Time to peak: 4-8 h
Plasma ½ life: 9-40 h

DOSING

• Loading dose 15-20 mg/kg oral in 3 divided doses q2-4h
• Maintenance dose 300 mg/day (range 200-1200 mg/day)

• 4-8 mg/kg/24h in divided doses bid or tid PO

UNWANTED EFFECTS

• Nausea
• Vomiting
• Nystagmus
• Delirium
• Dizziness
• Ataxia
• Altered speech
• Gingival hypertrophy
• Acne

PITFALLS/CONCERNS

• There are many drug interactions with anti-epileptics

NOTE

This information is drawn from a number of sources (see below). The reader is encouraged to access these and other relevant literature for more detail. As always, sound clinical judgment should be used in individual clinical cases. In particular, it should be remembered that there may be significant variation in the pharmokinetics of a drug resulting from a number of factors, including the individual patient’s metabolism/disease status and how the medication has been formulated.

SOURCES/REFERENCES

1. Brunton LL, Lazo JS, Parker KL, editors. Goodman and Gilman’s: the pharmacological basis of therapeutics. 11th ed. McGraw-Hill Professional; 2006.
2. Twycross R, Wilcock A. Palliative care formulary. 3rd ed. Radcliffe Medical Press Ltd; 2008.
3. Repchinsky C, editor. Compendium of pharmaceuticals and specialties (CPS): the Canadian drug reference for health professionals. 44th ed. Canadian Pharmacists Association; 2009.
4. Goldman A, Hain R, Liben S. Oxford textbook of palliative care for children. 1st ed. Oxford University Press; 2006.

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