NSAIDS AND PHENYTOIN

Serum phenytoin levels can be markedly increased by azapropazone, and toxicity can develop rapidly. A similar interaction has been seen with phenylbutazone, and it seems likely that oxyphenbutazone will interact similarly. Fosphenytoin, a prodrug of phenytoin, may interact similarly with these NSAIDs.
It has been suggested that the concurrent use of phenytoin and these NSAIDs should be avoided.