Phenylbutazone Diphenylhydantoin

Drugs known to displace warfarin from plasma binding sites include phenylbutazone, diphenylhydantoin, sulfonamides, and adrenocorticosteroids. 

Blood dyscrasias, mostly dose independent, are among the most important allergic-type adverse reactions to drugs. Aplastic anemia is a serious but rare (presumably) idiosyncratic reaction. It has been reported in association with chloramphenicol, quinacrine, phenylbutazone, mephenytoin, gold compounds, and potassium chlorate. Hemolytic anemia, thrombocytopenia, and agranulocytosis may result from an unusual, acquired sensitivity to a variety of widely used drugs including aminopyrine, phenylbutazone, phenothiazines, propylthiouracil, diphenylhydantoin, penicillins, chloramphenicol, sulfisoxazole, and tolbutamide. 

In humans, administration of o,p -DDD [l,l-dichloro-2-(4-chlorophenyl)-2-(2-chlorophenyl) ethane], phenobarbital, diphenylhydantoin, or phenylbutazone causes a marked elevation in the urinary excretion of 6 )5-hydroxycortisol presumably by accelerating the metabolism of glucocorticoids. Accordingly, treatment of animals with phenobarbital stimulates the hydroxylation by hepatic microsomes of corticosterone, deoxycorticosterone, cortisone, and cortisol, whereas 3-methylcholanthrene has negligible effect on the hydroxylation of cortisone or cortisol. The physiological consequences of this induction, however, remain obscure. 

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