A 46-year-old man underwent surgery to remove a glioma of the left brain lobe. An intravenous infusion of a drug was started to induce controlled hypotension to minimize blood loss during surgery. Which of the following drugs would be most appropriate for this purpose?

Correct Answer: D

Rationale: The correct answer is D: Nitroprusside. Nitroprusside is a potent vasodilator that can rapidly induce controlled hypotension by relaxing smooth muscle in blood vessels. This helps in minimizing blood loss during surgery. Labetalol (A) is a non-selective beta-blocker with alpha-blocking activity, which may not provide rapid hypotension. Hydralazine (B) is a direct vasodilator that can cause reflex tachycardia and may not be as effective in controlled hypotension. Nifedipine (C) is a calcium channel blocker primarily used for hypertension but does not provide rapid hypotension like nitroprusside.

Correct Answer: C

Rationale: The correct answer is C) Disopyramide. Disopyramide is a Class Ia antiarrhythmic drug that exhibits strong anticholinergic effects, which can lead to adverse effects such as dry mouth, blurred vision, urinary retention, and constipation. These anticholinergic effects can limit its use in patients, especially those with underlying conditions such as glaucoma, benign prostatic hyperplasia, or myasthenia gravis. A) Quinidine is a Class Ia antiarrhythmic drug that can cause cinchonism (side effects like tinnitus and blurred vision) but does not have significant anticholinergic effects. B) Procainamide is also a Class Ia antiarrhythmic drug that does not have strong anticholinergic effects, making it a safer choice compared to Disopyramide in patients who are sensitive to anticholinergic side effects. D) Flecainide is a Class Ic antiarrhythmic drug that does not possess anticholinergic properties and is not associated with the same limitations as Disopyramide. Understanding the specific side effect profiles of different antiarrhythmic drugs is crucial for healthcare providers to make informed decisions when selecting the most appropriate medication for individual patients. This knowledge helps in optimizing treatment outcomes while minimizing potential adverse effects and drug interactions.

Correct Answer: B

Rationale: The correct answer is B) Dipyridamole. The coronary steal phenomenon occurs when a vasodilator causes increased blood flow in non-stenotic vessels, leading to a "stealing" of blood from areas with existing stenosis. Dipyridamole is a coronary vasodilator that can induce coronary steal due to its ability to dilate normal coronary vessels more than stenotic ones. Option A) Glyceryl trinitrate is a vasodilator but is not known to cause coronary steal phenomenon. Option C) Propranolol is a beta-blocker that reduces heart rate and blood pressure, but it does not induce coronary steal. Option D) Diltiazem is a calcium channel blocker that also acts as a coronary vasodilator; however, it is not typically associated with coronary steal phenomenon. Understanding the concept of coronary steal phenomenon is crucial in pharmacology, especially when prescribing medications that can impact coronary blood flow in patients with coronary artery disease. Recognizing which drugs can lead to this phenomenon helps in making informed decisions to avoid potential adverse effects in patients with underlying cardiac conditions.

Correct Answer: D

Rationale: The correct answer is D) Platelets cannot generate fresh thromboxane synthetase and their turnover time is 5-7 days. Platelets are anucleate cells, meaning they lack a nucleus and are unable to synthesize new proteins. Thromboxane synthesis inhibition by aspirin is irreversible because aspirin acetylates and inactivates cyclooxygenase (COX) enzyme in platelets. Since platelets have a lifespan of 5-7 days, they cannot generate new thromboxane synthetase during this time, leading to the prolonged inhibition of thromboxane synthesis by aspirin. Option A) Aspirin persists in the body for 5-7 days is incorrect because aspirin itself is metabolized relatively quickly in the body. Option B) Aspirin-induced depletion of arachidonic acid lasts 5-7 days is incorrect because arachidonic acid levels can be restored within hours once aspirin is discontinued. Option C) Regeneration of aspirin-inhibited cyclooxygenase takes 5-7 days is incorrect because the inhibition of COX by aspirin is irreversible and does not rely on the regeneration of the enzyme. Understanding the mechanism of action of aspirin in platelets is crucial in pharmacology as it explains the long-lasting antiplatelet effects of aspirin and its clinical significance in preventing cardiovascular events.

Correct Answer: B

Rationale: In this scenario, the correct answer is B) Captopril. Captopril is an angiotensin-converting enzyme (ACE) inhibitor commonly associated with adverse effects such as neutropenia, a condition characterized by a low count of neutrophils, a type of white blood cell crucial for fighting infections. ACE inhibitors can sometimes lead to bone marrow suppression, resulting in neutropenia. Metoprolol (A) is a beta-blocker used to treat hypertension and other cardiovascular conditions. It is not typically associated with neutropenia. Lisinopril (C) is another ACE inhibitor like captopril, but it is less likely to cause neutropenia compared to captopril. Guanfecine (D) is a centrally acting alpha-2 adrenergic agonist used for hypertension and is not known to cause neutropenia. Educationally, understanding the adverse effects of cardiovascular drugs is crucial for healthcare professionals to make informed decisions when prescribing medications. Recognizing potential adverse effects allows for timely intervention and management to ensure patient safety and well-being. This knowledge underscores the importance of thorough medication assessments and monitoring for adverse reactions in clinical practice.