A nurse is giving dietary instructions to a client who has been prescribed cyclosporine. Which of the following food items would the nurse instruct the client to avoid?

Appeared in: DHS Staff Nurse - 2018 (Shift-2nd)

Explanation

Grapefruit and its juice contain compounds called furanocoumarins.
These compounds are potent inhibitors of the cytochrome P450 3A4 (CYP3A4) enzyme system, which is found in the liver and small intestine.
Cyclosporine is primarily metabolized by the CYP3A4 enzyme.
By inhibiting this enzyme, grapefruit juice prevents the breakdown of cyclosporine, leading to significantly increased blood concentrations of the drug.
Elevated cyclosporine levels dramatically increase the risk of severe toxicity, particularly kidney damage (nephrotoxicity) and high blood pressure (hypertension).

Option A: There is no known clinically significant interaction between red meats and cyclosporine. General dietary guidelines for health should be followed, but specific avoidance is not required.
Option B: Orange juice does not inhibit the CYP3A4 enzyme and is safe to consume with cyclosporine. In fact, due to the unpleasant taste of the oral cyclosporine solution, it is often recommended to mix it with orange juice or milk to improve palatability.
Option D: The instruction to avoid green leafy vegetables is specific to the anticoagulant medication warfarin (Coumadin). These vegetables are high in Vitamin K, which can counteract the effects of warfarin. This interaction does not apply to cyclosporine.

Clinical Relevance

Nursing practice connection: Use the key finding related to Drug-food interaction with cyclosporine to guide bedside assessment, documentation, and the next nursing action.
Patient education is a critical nursing role. For clients on cyclosporine, teaching them to strictly avoid all forms of grapefruit (fresh, juice, canned) is essential for preventing life-threatening toxicity.
Nurses must monitor for signs of cyclosporine toxicity, which include new-onset or worsening hypertension, elevated BUN and serum creatinine levels (indicating kidney dysfunction), tremors, and headache.
What if? If the client were taking the anticoagulant warfarin instead of cyclosporine, the nurse's advice regarding green leafy vegetables would be different. Instead of avoidance, the nurse would instruct the client to maintain a consistent weekly intake of these foods to prevent fluctuations in their INR (International Normalized Ratio).

How to Approach the Question

First, identify the key components of the question: the drug is 'cyclosporine' and the action is 'avoid' a specific 'food item'.
This is a pharmacology question that tests your knowledge of specific drug-food interactions.
Recall the metabolic pathway for cyclosporine. It is a substrate of the cytochrome P450 enzyme system, specifically CYP3A4.
Evaluate each food option based on this knowledge. Grapefruit juice is a classic, well-documented inhibitor of the CYP3A4 enzyme.
Analyze the distractors. Orange juice is safe and often used to mix the medication. Green leafy vegetables are a distractor related to warfarin (Vitamin K interaction). Red meat has no specific contraindication.
Based on the mechanism of action, conclude that grapefruit juice is the only food listed that must be strictly avoided to prevent drug toxicity.

Concept Tested & Keywords

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E6 Pharmacology Nursing Lilley 11e Part 3 p. 142-144

Practise the full DHS Staff Nurse - 2018 (Shift-2nd)

Attempt every question from this paper in a timed mock, then review the full solution for each one.