Interfered metabolism of dicumarol, phenytoin, tolbutamide & chlorpropamide. Interfered metabolism by phenytoin & acetaminophen. Subtherapeutic conc w/ phenobarb, rifampin. Antagonised effect w/ β-lactams against
Klebsiella pneumoniae, aminoglycosides against
E coli, ampicillin against certain Salmonella strains, penicillin against pneumococcus. Increased renal excretion by diuretics eg, mannitol, ethacrynic acid, hydrochlorothiazide.