Phenytoin
(Dilantin, Di-Phen, Diphenylan, Phenytex){oral} Fosphenytoin
(Cerebyx){intravenous}
Category:
Description:
Indications:
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Generalized
tonic-clonic seizures, simple or complex seizures, status epilepticus
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Nonepileptic
seizures associated with Reye’s syndrome or after head trauma
-
Fosphenytoin-
substitute for oral phenytoin when PO administration not feasible;
migraines, Bell’s palsy, ventricular dysrhythmias,
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Diabetic
neuropathy pain (non FDA approved)
Contraindications:
Precautions:
Adverse
Reactions (Side Effects):
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CNS:
ataxia, confusion, dizziness, drowsiness, fatigue, headache, insomnia,
nystagmus, paresthesias, psychiatric changes, slurred speech
-
CV:
CV collapse (when drug administered too rapidly IV), hypotension,
ventricular fibrillation
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EENT:
blurred vision, diplopia, gingival hyperplasia
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GI:
anorexia, constipation, hepatitis, jaundice, nausea, vomiting, weight
loss
-
GU:
nephritis
-
MEME:
agranulocytosis, aplastic anemia, leukopenia, lymphadenopathy,
megaloblastic anemia, thrombocytopenia
-
METAB:
hyperglycemia
-
SKIN:
alopecia, hirsutism, lupus erythematosus, rash, Stevens-Johnson
syndrome
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Dosage:
NOTE: Fosphenytoin 75mg
equivalent to 50mg phenytoin, after administration; the dose of IV
fosphenytoin is expressed as phenytoin equivalents (PE) to avoid the need
to perform molecular weight-based adjustments when converting between
fosphenytoin and phenytoin doses.
-
Adult:
Phenytoin
-
Seizures: IV loading dose 15-20 mg/kg based on recent dosing history and
serum levels, followed by 100mg PO or IV every 6-8 hours; PO
loading dose 1g divided 400mg, 300mg, 300mg given every 2 hours;
if load not necessary, may give 100mg 3 times daily, follow
levels; maintenance dose: 300mg daily or 5-6 mg/kg/day in divided
doses; once dosage established may use extended capsules and dose
daily
-
Neuritic
pain: PO 200-400mg daily
-
Fosphenytoin:
-
Status
epilepticus: IV 15-20mg PE/kg loading dose administered at
100-150mg PE/minute
-
Nonemergent
and maintenance dosing: IM/IV 10-20mg PE/kg loading dose
administered at a rate < or = 150mg PE/minute: maintenance
4-6mg PE/kg/day
-
Child:
Phenytoin
Special
considerations:
-
Therapeutic
range 10-20 mcg/ml; nystagmus appears at 20 mcg/ml, ataxia at 30
mcg/ml, dysarthria and lethargy at levels above 40 mcg/ml; lethal dose
2-5g
-
Pro-drug:
fosphenytoin rapidly converted to phenytoin in
vivo: minimal activity before conversion; water soluble, thus more
suitable for parenteral applications: doesn’t require cardiac
monitoring; can be administered at faster rate; no IV filter required;
compatible with both saline and dextrose mixtures; requires
refrigeration
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The information contained here is an
abbreviated summary. For more detailed and complete information, consult the
manufacturer's product information sheets or standard textbooks
Source: Operational Medicine 2001, Health
Care in Military Settings, NAVMED P-5139, May 1, 2001, Bureau
of Medicine and Surgery, Department of the Navy, 2300 E Street NW, Washington,
D.C., 20372-5300
This information is provided by The Brookside Associates. The Brookside
Associates, LLC. is a private organization, not affiliated with any governmental
agency. The opinions presented here are those of the author and do not
necessarily represent the opinions of the Brookside Associates or the Department
of Defense. The presence of any advertising on these pages does not constitute
an endorsement of that product or service by either the US Department of Defense
or the Brookside Associates. All material presented here is unclassified.
C. 2009, 2014, All Rights Reserved
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