Choose the group that is correct.
Select all that apply.

Nitroglycerin is a medication that dilates the blood vessels and improves blood flow to the heart. It is used to treat angina, a condition that causes chest pain due to reduced oxygen supply to the heart. However, nitroglycerin can lose its effectiveness over time if it is used continuously. This is called tolerance, and it means that the patient will need higher doses of the medication to achieve the same relief. To avoid tolerance, patients who use transdermal nitroglycerin patches are instructed to remove the patch at bedtime and apply a new one in the morning. This creates a nitrate-free interval of about 8 to 12 hours, which allows the body to restore its sensitivity to nitroglycerin.

Choice A is wrong because an allergic response is not a common side effect of nitroglycerin. Some patients may experience skin irritation or rash at the site of application, but this is usually mild and does not require discontinuation of the medication.

Choice C is wrong because overdosage is unlikely with transdermal nitroglycerin patches. The patches deliver a controlled amount of nitroglycerin through the skin over a period of time. The risk of overdosage is higher with other forms of nitroglycerin, such as tablets or sprays, which are taken as needed for acute angina attacks.

Choice D is wrong because forgetting to remove the patch in the morning is not a serious problem. The patch will continue to deliver nitroglycerin until it is removed, but it will not cause harm to the patient. However, it may reduce the effectiveness of the next patch if there is no nitrate-free interval between them.

This is because low potassium levels (hypokalemia) increase the sensitivity of the heart to digoxin and can lead to toxicity even with normal serum digoxin levels. Digoxin inhibits the sodium-potassium pump on the cardiac cells, which causes potassium to accumulate outside the cells.Low potassium levels in the blood create a larger gradient for potassium to move out of the cells, which enhances the effect of digoxin and can cause arrhythmias.

Choice B is wrong because calcium 9.2 mg/dL is within the normal range (8.5 to 10.2 mg/dL) and does not increase the risk of digoxin toxicity.However, high calcium levels (hypercalcemia) can potentiate the effects of digoxin and cause toxicity.

Choice C is wrong because sodium 140 mEq/L is within the normal range (135 to 145 mEq/L) and does not increase the risk of digoxin toxicity.However, high sodium levels (hypernatremia) can reduce the binding of digoxin to the sodium-potassium pump and decrease its efficacy.

Choice D is wrong because magnesium 2.2 mg/dL is within the normal range (1.7 to 2.4 mg/dL) and does not increase the risk of digoxin toxicity.However, low magnesium levels (hypomagnesemia) can increase the sensitivity of the heart to digoxin and cause toxicity.