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 accurate and appropriate for counseling a client who has undergone a kidney transplant and is taking cyclosporine as an immunosuppressant to prevent organ rejection. The client should avoid taking St. John's wort as an herb because it may reduce the effectiveness of cyclosporine. St. John's wort is an herb that is used to treat depression, anxiety, and other mood disorders¹². However, St. John's wort can induce the enzyme cytochrome P450 3A4, which is involved in the metabolism of cyclosporine, and decrease its blood level¹²³. This may increase the risk of organ rejection or transplant failure in the client¹²³.

Choice B reason: This statement is incorrect and inappropriate for counseling a client who has undergone a kidney transplant and is taking cyclosporine as an immunosuppressant to prevent organ rejection. The client should not take St. John's wort as an herb because it may enhance the effectiveness of cyclosporine. As mentioned above, St. John's wort can reduce the effectiveness of cyclosporine by lowering its blood level¹²³. Taking St. John's wort with cyclosporine may result in subtherapeutic doses of cyclosporine and compromise the client's transplant outcome¹²³.

Choice C reason: This statement is incorrect and inappropriate for counseling a client who has undergone a kidney transplant and is taking cyclosporine as an immunosuppressant to prevent organ rejection. The client should not take cyclosporine with grapefruit juice to increase its absorption. Grapefruit juice can inhibit the enzyme cytochrome P450 3A4, which is involved in the metabolism of cyclosporine, and increase its blood level¹²³. This may increase the risk of side effects or toxicity of cyclosporine, such as kidney damage, high blood pressure, tremors, headache, or infection¹²³.

Choice D reason: This statement is incorrect and inappropriate for counseling a client who has undergone a kidney transplant and is taking cyclosporine as an immunosuppressant to prevent organ rejection. The client should not take cyclosporine with milk or yogurt to improve its digestion. Milk or yogurt may decrease the absorption of cyclosporine and reduce its effectiveness¹². Cyclosporine should be taken on an empty stomach, at least one hour before or two hours after a meal¹². If the client experiences stomach upset from cyclosporine, he should consult his health care provider for advice¹².

Choice A reason: This statement is incorrect and inappropriate for identifying the interaction between echinacea and lisinopril. Echinacea does not interact with lisinopril, an ACE inhibitor for blood pressure. There is no evidence that echinacea affects the blood pressure or the pharmacokinetics of lisinopril¹².

Choice B reason: This statement is incorrect and inappropriate for identifying the interaction between echinacea and amoxicillin. Echinacea does not interact with amoxicillin, a penicillin antibiotic for infection. There is no evidence that echinacea affects the antibacterial activity or the pharmacokinetics of amoxicillin¹².

Choice C reason: This statement is correct and appropriate for identifying the interaction between echinacea and prednisone. Echinacea may interact with prednisone, a corticosteroid for inflammation, by reducing its effectiveness or increasing its side effects. Echinacea has immunostimulatory properties that may counteract the immunosuppressive effects of prednisone¹². Echinacea may also induce the enzyme cytochrome P450 3A4, which is involved in the metabolism of prednisone, and decrease its blood level¹². Furthermore, echinacea may increase the risk of infection or bleeding in people who take prednisone¹².

Choice D reason: This statement is incorrect and inappropriate for identifying the interaction between echinacea and metformin. Echinacea does not interact with metformin, a biguanide for diabetes mellitus. There is no evidence that echinacea affects the blood glucose or the pharmacokinetics of metformin¹².

Choice E reason: This statement is correct and appropriate for identifying the interaction between echinacea and fluoxetine. Echinacea may interact with fluoxetine, an SSRI for depression, by increasing its side effects or toxicity. Echinacea may inhibit the enzyme cytochrome P450 2D6, which is involved in the metabolism of fluoxetine, and increase its blood level¹². Echinacea may also increase the risk of serotonin syndrome, a potentially life-threatening condition caused by excessive serotonin in the brain, in people who take fluoxetine¹²..