The healthcare provider prescribes clopidogrel (Plavix) for a patient at risk for a myocardial infarction. While instructing the patient about the adverse effects and precautions associated with this drug, the nurse tells him that the following drugs should not be used while on clopidogrel unless the doctor is consulted. (Select all that apply.)

A. Vitamin K: Vitamin K is the antidote for warfarin, not heparin. Warfarin works by inhibiting the synthesis of vitamin K-dependent clotting factors in the liver. Therefore, vitamin K is used to reverse the effects of warfarin in cases of over-anticoagulation. It does not reverse the effects of heparin.

B. Deferoxamine: Deferoxamine is a chelating agent used to treat iron toxicity and aluminum overload. It is not indicated for reversing the effects of heparin.

C. Acetylcysteine: Acetylcysteine is used as an antidote for acetaminophen (paracetamol) overdose. It is not indicated for reversing the effects of heparin.

D. Protamine sulfate: This is the correct answer. Protamine sulfate is the antidote for heparin. It works by binding to heparin to form a stable complex, thereby neutralizing its anticoagulant effects. Protamine sulfate is commonly used in clinical practice to reverse the effects of heparin in situations such as hemorrhage or when rapid reversal of anticoagulation is needed, such as before surgery.

A. Increase the risk for bleeding: Herbal supplements like green tea, ginkgo, feverfew, garlic, and ginger can potentiate the effects of warfarin by enhancing its anticoagulant properties. This increases the risk of bleeding, as warfarin itself is a blood thinner designed to prevent clot formation. These herbs can further inhibit platelet aggregation or enhance anticoagulation, leading to a higher risk of bleeding complications.

B. Cause severe headache: While some herbal supplements can cause headaches as a side effect, this is not the primary concern when combined with warfarin. The interaction between these herbs and warfarin does not commonly result in severe headaches. The primary issue is the increased risk of bleeding.

C. Decrease the effects of the warfarin (Coumadin): These particular herbal supplements do not generally decrease the effects of warfarin. In fact, they are more likely to increase its anticoagulant effects. Some other substances might interfere with warfarin's efficacy, but the herbs listed are known to enhance its bleeding risk.

D. Cause severe hypotension: Severe hypotension is not a common result of combining these herbal supplements with warfarin. The primary interaction is related to the blood-thinning effects, not to blood pressure regulation. Herbal supplements that might affect blood pressure are not typically those that interact significantly with warfarin in this manner.