A diabetic client who is currently taking metformin is ordered a computerized tomography (CT) scan with contrast. The nurse understands that the client's metformin should be discontinued how many hours before receiving intravenous (IV) contrast?
24 hours
12 hours
6 hours
48 hours
The Correct Answer is B
A. Discontinuing metformin 24 hours before a CT scan is longer than necessary and not standard practice.
B. It is generally recommended that metformin be held for at least 12 hours before the administration of IV contrast to reduce the risk of lactic acidosis, especially in clients with renal impairment.
C. Six hours is insufficient time to ensure the medication is cleared from the system, considering the potential risks.
D. Discontinuing metformin for 48 hours is overly cautious and not necessary unless there are complications that arise after the contrast is administered.
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Correct Answer is B
Explanation
A. A high first-pass effect means that a significant amount of the drug is metabolized by the liver before reaching systemic circulation, making oral administration less effective.
B. Morphine with a high first-pass effect will be more effective when administered via non-enteral routes, such as IV or subcutaneous, to bypass the liver's initial metabolism.
C. The first-pass effect does not influence the kidney’s rate of excretion but rather the liver’s initial metabolism of the drug.
D. The liver, not the kidneys, is responsible for the first-pass metabolism, which occurs before the drug reaches systemic circulation when taken orally.
Correct Answer is A
Explanation
A. Hypokalemia increases the risk of digoxin toxicity because low potassium levels enhance digoxin's effects on the myocardium. Monitoring and correcting potassium levels is essential in clients on digoxin.
B. Hypophosphatemia is not directly linked to digoxin toxicity and is not a primary concern.
C. Hypocalcemia does not increase the risk of digoxin toxicity; in fact, hypercalcemia would be more concerning in terms of potential toxicity.
D. Hypernatremia does not have a significant effect on digoxin toxicity, so it is not a primary concern when assessing this medication’s safety.