Induction of hypersensitivity to a previously tolerated antiepileptic drug by a second antiepileptic drug.
OBJECTIVE
To describe the induction of hypersensitivity to one antiepileptic drug (AED) by a second AED.


METHODS
Case report and review of the relevant literature.


RESULTS
A patient is reported who was treated with phenytoin (PHT) for 6 months without adverse effect, but developed a hypersensitivity reaction with rash, fever, elevated liver enzymes, lymphadenopathy, and colitis 6 weeks after the introduction of carbamazepine (CBZ). PHT and CBZ were discontinued. Seizures continued despite treatment with valproic acid and clobazam. A decision was made to cautiously reintroduce PHT. Diffuse skin rash and pharyngitis appeared after two doses of PHT.


CONCLUSIONS
The AED hypersensitivity syndrome has been thought to occur as a consequence of preexisting pharmacogenetic and immunologic abnormalities. Our case demonstrates induction of hypersensitivity to an AED that had been formerly well tolerated, after a hypersensitivity reaction to another AED. This is distinct from simple cross-reactivity between one or more drugs. Such induction of hypersensitivity with AEDs has not been previously described.
Klassen
B D
BD
Division of Neurology, Dalhousie University, Halifax, Nova Scotia, Canada.
Sadler
R M
RM
D000328:Adult; D000927:Anticonvulsants / Q000009:adverse effects* / Q000276:immunology*; D002220:Carbamazepine / Q000009:adverse effects* / Q000276:immunology*; D003429:Cross Reactions / Q000276:immunology; D003875:Drug Eruptions / Q000209:etiology / Q000276:immunology; D004342:Drug Hypersensitivity / Q000209:etiology* / Q000276:immunology*; D004359:Drug Therapy, Combination; D004827:Epilepsy / Q000188:drug therapy* / Q000276:immunology; D006801:Humans; D008297:Male; D010597:Pharmacogenetics; D010672:Phenytoin / Q000009:adverse effects* / Q000276:immunology*
D000927:Anticonvulsants; D002220:Carbamazepine; D010672:Phenytoin