A patient with a history of chronic alcohol abuse has been admitted to the unit with cirrhosis. Upon review of the patient's laboratory test results, the nurse notes that the patient's ammonia level is elevated at 218 mcg/dL. What medication should the nurse prepare to administer?

Choice A reason:
The onset of warfarin is delayed, meaning it takes longer to achieve a therapeutic effect. Warfarin requires several days to adjust to effective anticoagulation levels because it works by inhibiting the synthesis of clotting factors that are already present and active in the bloodstream. In contrast, heparin has an immediate anticoagulant effect when administered, which is crucial for patients with acute conditions like deep vein thrombosis.

Choice B reason:
Warfarin does not prevent platelet aggregation. Instead, it works by inhibiting vitamin K-dependent clotting factors, which are essential for blood coagulation. Platelet aggregation is primarily inhibited by antiplatelet drugs like aspirin or clopidogrel, not anticoagulants like warfarin.

Choice C reason:
Heparin does not necessarily have fewer adverse effects compared to warfarin. Both anticoagulants have their specific risks and side effects. Heparin is preferred in acute settings due to its rapid onset of action, but it can cause complications like heparin-induced thrombocytopenia (HIT), which requires careful monitoring.

Choice D reason:
Heparin does not have a longer half-life than warfarin. In fact, heparin's half-life is relatively short, which is why it is often administered via continuous infusion or frequent subcutaneous injections. Warfarin has a longer half-life, but its delayed onset of action makes it less suitable for immediate anticoagulation needs.

Choice A reason:
Using a different antifungal agent might be necessary due to the potential interaction between voriconazole and warfarin. Voriconazole can increase the anticoagulant effects of warfarin, leading to an increased risk of bleeding. Therefore, selecting an alternative antifungal that does not interact with warfarin could be the safest option for the patient.
Choice B reason:
Reducing the dose of voriconazole may not adequately address the drug interaction issue. Voriconazole can significantly affect warfarin metabolism even at lower doses, leading to potential complications. Therefore, this choice is less likely to be recommended.
Choice C reason:
Administering intravenous voriconazole does not change its interaction with warfarin. The method of administration does not alter the drug's effect on warfarin metabolism, making this option inappropriate for managing the drug interaction.
Choice D reason:
Increasing the dose of warfarin is not a viable option as voriconazole increases warfarin's anticoagulant effect. This would further elevate the risk of bleeding and is not recommended. Thus, this option is incorrect.