Apparently normal phenytoin metabolism in a patient with phenytoin‐ induced rash and lymphadenopathy.

Abstract

A 10‐year old female on phenytoin therapy developed a rash and lymphadenopathy. H.p.l.c. assays of urinary metabolites indicated no differences in stereoselective metabolism of phenytoin to phenolic and dihydrodiol metabolites as compared with volunteers given the drug or with pediatric patients without adverse reactions. This suggests that no obvious difference in stereoselective metabolism of phenytoin to potentially toxic arene oxides exists between this patient and other patients on phenytoin. Our results are consistent with the hypothesis that differences in peripheral detoxication of phenytoin arene oxides and not differences in hepatic metabolism of phenytoin may be responsible for such adverse reactions.

Immunological Adverse Effects of Anticonvulsants

“…Pseudolymphoma may be defined as an enlargement of lymph nodes clinically simulating malignant lymphoma but without definite histological diagnostic criteria (see also Dorfman & Warnke 1974). The pseudolymphomatous reaction usually occurs after a variable latent period, disappears upon withdrawal of the offending drug and recurs after rechallenge (Cooke et al 1988;Maguire et al 1987). Only a few cases of pseudolymphoma regress spontaneously despite continuation of treatment (Seyfeddinipur 1976;Wilden & Scott 1978).…”

“…Phenytoin and carbamazepine are the two drugs most frequently involved, but there have been occasional reports with other drugs (Anthony 1970;Bercel et al 1950;Black & Fivenson 1989). In some cases, patients may be reactive to more than one agent (Black & Fivenson 1989;Kahn et al 1984;Maguire et al 1987;Reents et al 1989). The diagnosis of AILD should be seriously considered in any patient on anticonvulsant therapy with a lymphadenopathy of unknown origin.…”