Which of the following drugs most likely caused the adverse effect of dizziness and fainting when standing up rapidly?

Correct Answer: D

Rationale: The correct answer is D: Prazosin. Prazosin is an alpha-1 adrenergic blocker that can cause orthostatic hypotension, leading to dizziness and fainting when standing up rapidly. It works by dilating blood vessels, which can cause a sudden drop in blood pressure upon standing. Propranolol (A) is a beta-blocker and can cause dizziness but is less likely to cause orthostatic hypotension. Minoxidil (B) is a vasodilator that can cause rapid heart rate but not typically dizziness upon standing. Hydralazine (C) is a direct vasodilator that can cause reflex tachycardia but is less likely to cause orthostatic hypotension compared to alpha-1 blockers like Prazosin.

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.

Correct Answer: B

Rationale: In this scenario, the correct answer is B) Premature atrial contractions. Premature atrial contractions are characterized by early and abnormal P waves on an electrocardiogram (ECG). In this case, the client's heart rate of 70 with early and malformed P waves suggests the occurrence of premature atrial contractions. Option A) Normal sinus rhythm is incorrect because the presence of early and malformed P waves indicates an abnormality in the cardiac rhythm, deviating from the normal sinus rhythm pattern. Option C) Frequent PVCs (Premature Ventricular Contractions) is incorrect as PVCs would manifest as early, wide QRS complexes on the ECG, not malformed P waves. Option D) Ventricular escape rhythm is incorrect in this context as it typically presents with a slow heart rate and originates from the ventricles, not the atria where the P wave abnormalities are observed. Educationally, understanding ECG findings and their implications is crucial for healthcare professionals, especially those involved in cardiovascular care. Recognizing different ECG patterns allows for accurate interpretation and timely intervention in clinical practice to ensure optimal patient outcomes.