Digoxin (Lanoxin) is a cardiac glycoside that is among the oldest medications used for heart failure.
What are its two primary actions?
Positive chronotropy and negative inotropy.
Negative inotropy and negative chronotropy.
Positive inotropy and negative chronotropy.
Positive inotropy and positive chronotropy.
The Correct Answer is C
Digoxin is a cardiac glycoside that increases the force of heart contractions (positive inotropy) and decreases the heart rate (negative chronotropy) by inhibiting the sodium-potassium ATPase pump in the cardiac cell membranes and affecting the autonomic tone. This helps to improve the symptoms of heart failure and to control the ventricular rate in atrial fibrillation.
Choice A is wrong because positive chronotropy means increasing the heart rate, which is the opposite of what digoxin does.
Choice B is wrong because negative inotropy means decreasing the force of heart contractions, which is also the opposite of what digoxin does.
Choice D is wrong because positive inotropy and positive chronotropy would both increase the workload of the heart, which is not desirable in heart failure or atrial fibrillation.
Normal ranges for digoxin are 0.5 to 2 ng/mL for heart failure and 0.8 to 2 ng/mL for atrial fibrillation. Digoxin has a narrow therapeutic window and can cause serious side effects if overdosed or underdosed.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Atorvastatin is a type of statin, which are the most potent antilipidemic agents and have proven to lower the risk of myocardial infarction. Statins work by inhibiting an enzyme called HMG-CoA reductase, which is involved in the synthesis of cholesterol in the liver.By reducing the production of cholesterol, statins lower the levels of low-density lipoprotein (LDL) and triglycerides, and slightly increase the levels of high-density lipoprotein (HDL) in the blood.
Choice B, niacin, is wrong because niacin is not as effective as statins in lowering LDL and preventing cardiovascular events.Niacin is a water-soluble vitamin that can lower LDL and triglycerides, and increase HDL, but it can also cause flushing, itching, and liver toxicity.
Choice C, gemfibrozil, is wrong because gemfibrozil is a type of fibric acid derivative, which are mainly used to lower triglycerides and increase HDL, but have little effect on LDL.
Fibric acid derivatives work by activating a receptor called PPAR-alpha, which regulates the metabolism of lipids in the liver and muscle.Fibric acid derivatives can also increase the risk of gallstones and muscle damage.
Choice D, ezetimibe, is wrong because ezetimibe is a selective cholesterol absorption inhibitor, which blocks the absorption of dietary and biliary cholesterol in the intestine.Ezetimibe can lower LDL by about 15-20%, but it has not been shown to reduce the risk of myocardial infarction on its own.Ezetimibe is usually combined with a statin for better efficacy and safety.
Normal ranges for lipid levels are:
• Total cholesterol: less than 200 mg/dL
• LDL cholesterol: less than 100 mg/dL
• HDL cholesterol: more than 40 mg/dL for men and more than 50 mg/dL for women
• Triglycerides: less than 150 mg/dL
Correct Answer is B
Explanation
Nitroglycerin transdermal patches are used to prevent episodes of angina (chest pain) in people who have coronary artery disease (narrowing of the blood vessels that supply blood to the heart).Nitroglycerin is a vasodilator that works by relaxing the blood vessels so that the heart does not need to work as hard and therefore does not need as much oxygen.However, if nitroglycerin is used continuously, the body may develop tolerance to its effects, meaning that it will not work as well to prevent angina attacks.Therefore, it is important to remove the patch at bedtime and apply a new one in the morning, leaving a 10-12 hour nitrate-free interval.This way, the body can restore its sensitivity to nitroglycerin and avoid angina episodes during the day.
Choice A is wrong because allergic response is not a common reason to remove the patch at night.Although some people may experience skin irritation or rash from the patch, this is usually mild and does not require discontinuation of the medication.If the skin reaction is severe or bothersome, the patch can be applied to a different area of the skin or switched to another form of nitroglycerin.
Choice C is wrong because overdose is unlikely to occur from using the patch as prescribed.Nitroglycerin patches come in doses ranging from 0.1 milligrams per hour to 0.8 mg/hr, and should be placed on clean, dry, and hairless skin for 12-14 hours and removed for 10-12 hours.If a patch loosens or falls off, it should be replaced with a fresh one.Overdose symptoms may include severe headache, dizziness, blurred vision, nausea, vomiting, sweating, chest pain, fast or irregular heartbeat, difficulty breathing, fainting, or seizures.If these occur, the patch should be removed immediately and medical attention should be sought.
Choice D is wrong because management of BPH (benign prostatic hyperplasia) is not related to nitroglycerin use.
BPH is a condition
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