Tick the antimalarial drug belonging to pyrimidine derivatives:

Correct Answer: B

Rationale: In the context of pharmacology, understanding the classification of antimalarial drugs based on their chemical structure is crucial for effective medication management. In this question, the correct answer is B) Pyrimethamine, which belongs to pyrimidine derivatives. Here's the detailed rationale: Pyrimethamine is a dihydrofolate reductase inhibitor used in the treatment of malaria. It is classified as a pyrimidine derivative due to its structural composition. Pyrimidine derivatives act by interfering with the folate synthesis pathway in the parasite, leading to its death. Now, let's analyze why the other options are incorrect: A) Mefloquine is not a pyrimidine derivative. It is an antimalarial drug belonging to the 4-aminoquinoline class and works by accumulating in the acidic food vacuoles of the parasite, interfering with heme polymerization. C) Quinidine is a cinchona alkaloid and is primarily used as an antiarrhythmic drug for treating cardiac arrhythmias. It is not an antimalarial drug and does not belong to pyrimidine derivatives. D) Chloroquine is also not a pyrimidine derivative but rather an aminoquinoline antimalarial drug. It acts by accumulating in the parasite's acidic digestive vacuole, preventing the detoxification of heme. Educational Context: Understanding the classification of drugs based on their chemical structure is fundamental in pharmacology. It helps healthcare professionals differentiate between drug classes, understand their mechanisms of action, predict potential side effects, and make informed decisions regarding drug selection and therapy management. This knowledge is essential for safe and effective pharmacotherapy in clinical practice.

Correct Answer: D

Rationale: The patient with prostatic hyperplasia was experiencing frequent nocturia and was diagnosed with poorly controlled hypertension. The addition of a new drug to the therapy likely caused adverse effects related to the patient's prostatic hyperplasia. Prazosin, an alpha-1 blocker, is known to relax smooth muscle in the prostate and bladder neck, potentially worsening symptoms of prostatic hyperplasia such as increased urinary frequency and urgency. Therefore, Prazosin is the most likely drug to have caused adverse effects in this patient.

Correct Answer: A

Rationale: Isosorbide mononitrate and nifedipine are appropriate for a patient with hypertrophic cardiomyopathy as they help reduce the workload on the heart and improve blood flow without causing negative effects on the heart muscle. Nitroglycerin and captopril are not commonly used for this condition, and verapamil and metoprolol are not the first-line treatment options. Therefore, the correct answer is A.

Correct Answer: B

Rationale: In the context of pharmacology of cardiovascular drugs, understanding the mechanism of action of medications used in different types of angina is crucial. In this case, the correct answer is B) Nifedipine. Nifedipine is a calcium channel blocker that exerts spasmolytic actions by inhibiting calcium influx into smooth muscle cells, leading to vasodilation. This vasodilation helps to increase coronary blood supply by reducing coronary artery spasm, making it an effective treatment for Prinzmetal's angina, which is characterized by coronary artery spasm. Now, let's discuss why the other options are incorrect: A) Nitroglycerin: Nitroglycerin is a vasodilator that primarily acts on veins, reducing preload and myocardial oxygen demand. While it is commonly used in the treatment of angina, it does not have direct spasmolytic actions to increase coronary blood supply. C) Timolol: Timolol is a beta-blocker that works by reducing heart rate and contractility, thus decreasing myocardial oxygen demand. It does not have spasmolytic actions to increase coronary blood supply. D) Isosorbide mononitrate: Isosorbide mononitrate is a nitrate that, like nitroglycerin, primarily acts as a vasodilator to reduce preload and myocardial oxygen demand. It does not possess spasmolytic actions to increase coronary blood supply. Educationally, understanding the specific mechanisms of action of different classes of cardiovascular drugs is essential for selecting the most appropriate medication for different types of angina. Nifedipine's spasmolytic actions make it a suitable choice for Prinzmetal's angina, highlighting the importance of targeting specific mechanisms of the condition for optimal treatment outcomes.

Correct Answer: B

Rationale: In the context of pharmacology of cardiovascular drugs, understanding the specific mechanisms of action of each drug class is crucial to predict their potential side effects. In this case, the correct answer is B) Nifedipine, as it belongs to the dihydropyridine calcium channel blockers (CCBs) class. Nifedipine primarily acts on vascular smooth muscle to cause vasodilation, but it can also lead to reflex tachycardia due to its potent vasodilatory effects. This reflex tachycardia is a compensatory response by the body to maintain cardiac output in the face of decreased systemic vascular resistance. A) Amlodipine is also a dihydropyridine CCB like nifedipine, but it is less likely to induce reflex tachycardia compared to nifedipine due to its longer duration of action and smoother pharmacokinetic profile. C) Diltiazem and D) Verapamil are non-dihydropyridine CCBs. These drugs primarily act on the myocardium to decrease cardiac contractility and heart rate. They are more likely to cause bradycardia rather than tachycardia as a side effect. Educationally, this question highlights the importance of recognizing the different subtypes of calcium channel blockers and their specific effects on the cardiovascular system. It underscores the need for healthcare professionals to be aware of potential side effects associated with different antianginal drugs to make informed clinical decisions and provide safe and effective patient care. Understanding these nuances can help in optimizing therapy and managing adverse effects in patients with cardiovascular conditions.