The administration of folic acid to institutionalized epileptic adults with phenytoin-induced gingival hyperplasia. A double-blind, randomized, placebo-controlled, parallel study.

Twenty severely retarded institutionalized epileptic adults with phenytoin-induced gingival hyperplasia were divided into two groups and received a daily 3 mg capsule of either folic acid or lactose for 16 weeks in a randomized, double-blind, parallel study. Serum folate and phenytoin levels were recorded at baseline and on completion of the study. Twelve areas of the gingiva on each patient were graded at 4-week intervals for 16 weeks with respect to the three indexes: hyperplasia, gingival health, and plaque index. There were no significant differences between treatment groups for any of the three indexes over time. The poststudy serum folate levels were three times baseline levels for the active drug group (p less than 0.001) but unchanged in the placebo group. Phenytoin blood levels that began within the therapeutic window (10 to 20 micrograms/ml) tended to remain within the therapeutic window for both groups, with no reported seizure activity. A single daily oral 3 mg capsule of folic acid did not show efficacy as the sole therapeutic agent in the reduction of phenytoin-induced gingival hyperplasia.