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.)

The correct answer is

C. "I should take digoxin with food or milk to prevent stomach upset."

Choice A reason: This statement is correct and does not indicate a need for further teaching. The client should avoid taking licorice as an herb because it may cause irregular heart rhythms. Licorice contains glycyrrhizin, which can lower the potassium level in the blood and increase the risk of digoxin toxicity. Licorice may also increase blood pressure and interfere with the effects of some blood pressure medications.

Choice B reason: This statement is also correct and does not indicate a need for further teaching. The client should monitor his pulse rate and report any changes to his healthcare provider. Digoxin can affect the heart rate and rhythm, and cause bradycardia (slow heart rate) or arrhythmias (irregular heartbeats)¹². The client should check his pulse before taking digoxin, and if it is below 60 beats per minute, he should skip the dose and call his healthcare provider. The client should also report any signs of digoxin toxicity, such as nausea, vomiting, loss of appetite, blurred vision, yellow or green halos around objects, confusion, or weakness.

Choice C reason: This statement is incorrect and indicates a need for further teaching. The client should not take digoxin with food or milk to prevent stomach upset. Food or milk may decrease the absorption of digoxin and reduce its effectiveness. Digoxin should be taken on an empty stomach, at least one hour before or two hours after a meal. If the client experiences stomach upset from digoxin, he should consult his healthcare provider for advice.

Choice D reason: This statement is also correct and does not indicate a need for further teaching. The client should check his weight daily and report any sudden increase to his healthcare provider. Digoxin is used to treat heart failure, a condition in which the heart cannot pump enough blood to meet the body's needs¹². One of the symptoms of heart failure is fluid retention, which can cause weight gain, swelling of the legs or ankles, shortness of breath, or difficulty breathing. A sudden increase in weight may indicate worsening of heart failure and require adjustment of the treatment plan.

The correct answer is

C. "Increasing the therapeutic effect of warfarin and the risk of bleeding."

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 increases 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 level. 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-warfarin.

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 prolongs 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 level. 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-warfarin.

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 factors. Ginkgo biloba contains flavonoids and terpenoids that have antiplatelet and anticoagulant properties. Therefore, taking ginkgo biloba with warfarin may increase the risk of bleeding complications, such as hemorrhage or intracranial hemorrhage.

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 warfarin. Therefore, taking ginkgo biloba with warfarin may require more frequent monitoring of INR to adjust the dose of warfarin accordingly.