Fosphenytoin in infants.
In comparison with phenytoin preparations, which have a pH value of 11, fosphenytoin, a phosphorylated prodrug of phenytoin, has a pH value of only 8.6, which decreases the risk of cardiovascular and cutaneous side effects. The near-neutral pH value of fosphenytoin allows effective intravenous or intramuscular administration. A 1-mg phenytoin equivalent (PE) of fosphenytoin is converted to 1 mg of phenytoin in adults. We describe four infants whose seizures were treated with intravenous fosphenytoin. We had difficulty maintaining therapeutic serum phenytoin levels of 10 to 20 microg/mL on doses of 5 to 8 mgPE/kg/day, and many bolus doses of 5 to 10 mgPE/kg or maintenance doses of more than 10 mgPE/kg/day were given. Despite increased doses in three out of the four patients, a therapeutic serum phenytoin level was not maintained. From our experience, careful and individual dosing of fosphenytoin in this age group can be considered.
Takeoka
M
M
Department of Neurology, Massachusetts General Hospital, Boston 02114, USA.
Krishnamoorthy
K S
KS
Soman
T B
TB
Caviness
V S
VS
D000927:Anticonvulsants / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010634:Phenobarbital / Q000627:therapeutic use; D010672:Phenytoin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000627:therapeutic use*; D011355:Prodrugs / Q000008:administration & dosage / Q000627:therapeutic use*; D012640:Seizures / Q000097:blood / Q000188:drug therapy*
D000927:Anticonvulsants; D011355:Prodrugs; D010672:Phenytoin; C043114:fosphenytoin; D010634:Phenobarbital