The effect of the anticonvulsants phenobarbital and diphenylhydantoin on intestinal absorption of calcium.

The effect of anticonvulsant drugs (phenobarbital and diphenylhydantoin) on the metabolic balance of calcium and on its intestinal absorption, as measured by an in situ intraluminal perfusion method, was studied in rats. The administration of these drugs produced: (a) an increase of the fecal excretion of calcium,. (b) a decrease of the intestinal absorption of calcium (45Ca). Both effects were more intense in rats treated with phenobarbital. There is evidence to suggest that the anticonvulsant drugs affect the intestinal mechanism of active transport of calcium.