Which medication is known to increase the risk of bleeding when taken with warfarin sodium?

Trimethoprim/sulfamethoxazole (Bactrim DS) can increase the risk of bleeding in patients taking warfarin sodium due to its effects on the metabolism of warfarin. This combination can enhance the anticoagulant effects of warfarin by inhibiting the cytochrome P450 enzymes in the liver that metabolize warfarin, particularly CYP2C9. When these enzymes are inhibited, the levels of warfarin in the bloodstream can rise, leading to an increased risk of bleeding complications.

In contrast, the other options do not significantly affect warfarin metabolism or increase the risk of bleeding in a similar manner. Sucralfate (Carafate) primarily acts locally in the gastrointestinal tract and does not interact with warfarin. Losartan (Cozaar) is an angiotensin receptor blocker that does not significantly impact warfarin's anticoagulant effect. Furosemide (Lasix) is a diuretic that does not have a direct interaction with warfarin and does not notably increase the risk of bleeding. Thus, the presence of Bactrim DS represents a notable concern for those on warfarin therapy due to its potential to enhance the effects and, consequently