Action mechanism of methotrexate is:

Correct Answer: A

Rationale: The correct answer is A: Inhibition of dihydrofolate reductase. Methotrexate inhibits dihydrofolate reductase, an enzyme involved in the synthesis of nucleotides. This leads to decreased production of DNA, RNA, and proteins, inhibiting cell proliferation. Choices B and C are incorrect as methotrexate does not activate cell differentiation or deplete serum asparagine. D is incorrect as methotrexate's mechanism of action is specifically through inhibiting dihydrofolate reductase, not all of the above.

Correct Answer: C

Rationale: The correct answer is C: Amiodarone. This drug is an antiarrhythmic medication commonly associated with side effects such as palpitations, insomnia, diarrhea, and increased sweating. Quinidine (A) and Lidocaine (B) are also antiarrhythmic drugs but are less likely to cause the specific symptoms described. Adenosine (D) is a drug used for treating certain types of irregular heartbeats but does not typically cause the combination of symptoms mentioned. Therefore, based on the patient's symptoms, Amiodarone is the most likely drug taken.

Correct Answer: B

Rationale: The correct answer is B) Diltiazem. Diltiazem is a calcium channel blocker that directly affects the AV node by delaying calcium-channel depolarization. This action results in a decreased conduction velocity through the AV node, which can be beneficial in conditions such as supraventricular tachycardia. Option A) Lidocaine is a sodium channel blocker used primarily for ventricular arrhythmias and does not directly affect calcium-channel depolarization in the AV node. Option C) Bretylium is an antiarrhythmic agent that works by inhibiting catecholamine release and is not directly involved in calcium-channel depolarization in the AV node. Option D) Quinidine is a Class I antiarrhythmic agent that blocks sodium channels and delays repolarization but does not directly target calcium-channel depolarization in the AV node. Understanding the mechanisms of action of cardiovascular drugs is crucial for nurses and other healthcare professionals to provide safe and effective care to patients with cardiovascular conditions. Knowing how each drug affects specific aspects of cardiac function, such as conduction through the AV node, can help in selecting the most appropriate medication for a patient's condition. It is essential for NCLEX candidates to grasp these concepts to make informed clinical decisions and ensure patient safety.

Correct Answer: D

Rationale: In the context of NCLEX Pharmacology Cardiovascular Drugs, the correct answer is D) Atrial fibrillation. Digoxin is commonly used in the management of atrial fibrillation due to its ability to increase cardiac contractility and slow down the heart rate. In patients with atrial fibrillation, digoxin can help improve cardiac output and control the heart rate, thus reducing symptoms and improving overall cardiac function. Option A) Thyrotoxicosis is incorrect because digoxin is not typically indicated for this condition. Thyrotoxicosis is usually managed with medications that target the thyroid hormone levels. Option B) Beriberi is incorrect as digoxin is not a treatment for thiamine (Vitamin B1) deficiency, which is the underlying cause of Beriberi. Option C) Cor pulmonale is also an incorrect option as digoxin is not the first-line treatment for this condition. Treatment for cor pulmonale involves addressing the underlying pulmonary condition and optimizing oxygenation. Understanding the specific indications for medications like digoxin is crucial for nursing practice, especially in managing cardiovascular conditions. Nurses must be able to differentiate between various cardiac conditions and understand the appropriate pharmacological interventions to provide safe and effective patient care. This question evaluates the nurse's knowledge of pharmacological management of atrial fibrillation and reinforces the importance of accurate medication administration based on the patient's condition.

Correct Answer: B

Rationale: In this scenario, the correct answer is B) Gemfibrozil. Gemfibrozil is a fibric acid derivative commonly used to reduce high levels of triglycerides in the blood. Triglycerides are a type of fat found in the blood, and elevated levels are associated with an increased risk of cardiovascular disease, especially in patients with coronary artery disease. Gemfibrozil works by decreasing the production of triglycerides in the liver and increasing the removal of triglycerides from the blood. Option A) Propranolol is a beta-blocker commonly used to treat hypertension and certain heart conditions, but it does not have a significant effect on lipid levels. Option C) Cholestyramine is a bile acid sequestrant that works by binding to bile acids in the intestine, but it is more effective in lowering cholesterol levels rather than triglycerides. Option D) Lovastatin is a statin medication that primarily targets lowering LDL cholesterol levels. While it may have some effect on triglyceride levels, it is not as effective as fibric acid derivatives like gemfibrozil in lowering triglycerides. Educational Context: Understanding the rationale behind selecting the appropriate hypolipidemic drug based on the lipid profile of the patient is crucial in the management of cardiovascular diseases. Different classes of medications target specific lipid abnormalities, and choosing the right drug based on the individual patient's lipid profile can help optimize treatment outcomes and reduce cardiovascular risk factors. Gemfibrozil, in this case, is the most appropriate choice for reducing elevated triglyceride levels in a patient with coronary artery disease, ultimately improving their cardiovascular health.