A nurse is reviewing the medication list of a client who uses echinacea as a CAM product to boost his immune system function. The nurse should identify that echinacea may interact with which of the following conventional drugs? (Select all that apply.)

Choice A reason: This statement is incorrect and inappropriate for describing the interaction between ginkgo biloba and warfarin. Ginkgo biloba does not enhance the absorption of warfarin and increase its blood level. In fact, ginkgo biloba may induce the enzyme cytochrome P450 3A4, which is involved in the metabolism of warfarin, and reduce its blood level¹². However, this effect may not be clinically significant, as warfarin has two enantiomers (R- and S-warfarin) that are metabolized by different enzymes, and S-warfarin is more potent than R-warfarin¹².

Choice B reason: This statement is incorrect and inappropriate for describing the interaction between ginkgo biloba and warfarin. Ginkgo biloba does not reduce the metabolism of warfarin and prolong its action. As mentioned above, ginkgo biloba may induce the enzyme cytochrome P450 3A4, which is involved in the metabolism of warfarin, and reduce its blood level¹². However, this effect may not be clinically significant, as warfarin has two enantiomers (R- and S-warfarin) that are metabolized by different enzymes, and S-warfarin is more potent than R-warfarin¹².

Choice C reason: This statement is correct and appropriate for describing the interaction between ginkgo biloba and warfarin. Ginkgo biloba may increase the therapeutic effect of warfarin and the risk of bleeding by inhibiting platelet aggregation and interfering with clotting factors¹². Ginkgo biloba contains flavonoids and terpenoids that have antiplatelet and anticoagulant properties¹². Therefore, taking ginkgo biloba with warfarin may increase the risk of bleeding complications, such as hemorrhage or intracranial hemorrhage¹²³.

Choice D reason: This statement is incorrect and inappropriate for describing the interaction between ginkgo biloba and warfarin. Ginkgo biloba does not interfere with the monitoring of warfarin and its INR value. INR stands for international normalized ratio, which is a measure of how long it takes blood to clot. Warfarin therapy requires regular monitoring of INR to ensure that the dose is appropriate and effective¹². Ginkgo biloba does not affect the INR test itself, but it may affect the INR value by increasing the anticoagulant effect of warfarin¹². Therefore, taking ginkgo biloba with warfarin may require more frequent monitoring of INR to adjust the dose of warfarin accordingly¹².

Choice A reason: This statement is correct and reflects one of the possible adverse effects or interactions that may occur with biologically based therapies such as herbs and supplements. Allergic reactions or hypersensitivity can occur when the body's immune system reacts to a foreign substance, such as a plant extract or a dietary supplement, and produces antibodies and other chemicals that cause symptoms such as itching, rash, hives, swelling, or anaphylaxis (a severe and potentially life-threatening reaction)¹². Some examples of herbs or supplements that may cause allergic reactions include echinacea, chamomile, garlic, ginkgo, and bee pollen¹².

Choice B reason: This statement is also correct and reflects another possible adverse effect or interaction that may occur with biologically based therapies such as herbs and supplements. Hepatic or renal toxicity or dysfunction can occur when the liver or the kidneys are damaged or impaired by a substance, such as a plant extract or a dietary supplement, that may be toxic or interfere with their normal function¹². Some examples of herbs or supplements that may cause hepatic or renal toxicity or dysfunction include kava, comfrey, chaparral, licorice, ephedra, and aristolochia¹².

Choice C reason: This statement is also correct and reflects another possible adverse effect or interaction that may occur with biologically based therapies such as herbs and supplements. Gastrointestinal distress or bleeding can occur when the stomach or the intestines are irritated or injured by a substance, such as a plant extract or a dietary supplement, that may cause inflammation, ulceration, perforation, or bleeding¹². Some examples of herbs or supplements that may cause gastrointestinal distress or bleeding include aloe vera, cascara sagrada, senna, ginger, ginseng, garlic, ginkgo, and feverfew¹².

Choice D reason: This statement is correct because it includes all of the above statements. Biologically based therapies such as herbs and supplements may cause various adverse effects or interactions depending on the type, dose, duration, quality, purity, and combination of these products¹². Therefore, choice D is the best answer for assessing the client for possible adverse effects or interactions that may occur with biologically based therapies.