Increase & decrease PT/INR response w/ antiarrhythmics, antibiotics, anticonvulsants, antidepressants, antineoplastics, antithyroid drugs, diuretics, systemic fungal medications, gastric acidity & peptic ulcer agents, hypnotics, hypolipidemics, adrenocortical steroids, TB agents, vit K, alcohol, chloral hydrate, cholestyramine, cyclophosphamide, methimazole, moricizine HCl, phenytoin, prednisone, propylthiouracil, ranitidine. Concomitant administration w/ ticlopidine may be associated w/ cholestatic hepatitis. Increase effects w/ botanical (herb) medicines [eg bromelains, danshen, dong quai (Angelica sinensis), garlic, ginkgo biloba, ginseng]; decrease w/ coenzyme Q
10 (ubidecarenone) & St. John's wort. Hypoglycaemic agents (chlorpropamide & tolbutamide) & anticonvulsants (phenytoin & phenobarb). Inhibit platelet aggregation & can cause GI bleeding, peptic ulceration &/or perforation w/ NSAIDs including aspirin.