A single case report indicates that phenytoin can reduce or abolish effects of streptozocin
Clinical evidence,mechanism, importance and management
A patient with an organic hypoglycaemic syndrome, due to a metastatic apud cell carcinoma of pancreas, who was taking streptozocin 2 g daily with phenytoin 400mg daily for 4 days, failed to show expected response until phenytoin was withdrawn (See reference number 1). It would seem that phenytoin inhibited effects of streptozocin by some mechanism as yet unknown. Although this is an isolated case report its authors recommend that concurrent use should be avoided.
1. Koranyi L,Gero L. Influence of diphenylhydantoin on the effect of streptozotocin. BMJ (1979) 1, 127.