The major causes of hypomagnesaemia are:

Correct Answer: D

Rationale: In pharmacology, understanding the major causes of hypomagnesemia is crucial to ensure safe and effective use of cardiovascular drugs. Option D, "All of the above," is the correct answer because hypomagnesemia can indeed result from insufficient dietary intake (malnutrition), abnormal gastrointestinal loss (severe diarrhea, chronic alcoholism), and abnormal renal loss (diabetes mellitus, certain drug therapies). Option A is incorrect because while insufficient dietary intake can lead to hypomagnesemia, it is not the only cause. Option B is incorrect as it focuses solely on abnormal gastrointestinal loss and does not encompass other significant causes. Option C is also incorrect as it only mentions abnormal renal loss without considering other important factors. Educationally, knowing the major causes of hypomagnesemia helps healthcare professionals recognize and address this electrolyte imbalance, which is crucial for the proper functioning of the cardiovascular system. Understanding these causes also informs healthcare providers about potential risks associated with certain medications and medical conditions, enabling them to make informed decisions in clinical practice.

Correct Answer: D

Rationale: In the context of pharmacology, understanding the mechanism of action of drugs is crucial for safe and effective prescribing. In the case of Amphotericin B, the correct answer is D) Alteration of cell membrane permeability. This antifungal medication works by binding to ergosterol in the fungal cell membrane, leading to the formation of pores that result in leakage of intracellular contents and ultimately cell death. Option A) Inhibition of cell wall synthesis is incorrect because this mechanism is typically associated with drugs like beta-lactam antibiotics targeting bacteria, not fungi. Option B) Inhibition of fungal protein synthesis is incorrect as Amphotericin B does not directly interfere with protein synthesis. Option C) Inhibition of DNA synthesis is also incorrect as this is not the primary mode of action of Amphotericin B. Educationally, grasping the mechanism of action of drugs like Amphotericin B aids in understanding how they exert their therapeutic effects and potential side effects. This knowledge is essential for healthcare professionals to make informed decisions when selecting and administering medications to patients, especially in cases of severe fungal infections where Amphotericin B is commonly used.

Correct Answer: C

Rationale: In this question about antimalarial drugs belonging to 8-aminoquinoline derivatives, the correct answer is C) Primaquine. Primaquine is classified as an 8-aminoquinoline derivative and is specifically used for the treatment of malaria caused by Plasmodium vivax and Plasmodium ovale. Now, let's analyze why the other options are incorrect: A) Doxycycline is a tetracycline antibiotic commonly used for treating various bacterial infections, not malaria caused by Plasmodium species sensitive to 8-aminoquinolines. B) Quinidine is an antiarrhythmic agent used to treat certain heart rhythm disorders, not malaria. D) Chloroquine is also an antimalarial drug, but it belongs to the 4-aminoquinoline class, not the 8-aminoquinoline derivatives as specified in the question. Educational context: Understanding the classification of antimalarial drugs is crucial in pharmacology to ensure the appropriate selection of medications for treating specific types of malaria infections. Knowing the distinct characteristics of different drug classes helps healthcare providers make effective and safe treatment decisions for patients with malaria.

Correct Answer: C

Rationale: In this question, the correct answer is C) Cyclophosphamide. Cyclophosphamide is an anticancer alkylating drug that is a derivative of chloroethylamine. Alkylating agents work by attaching alkyl groups to DNA, which prevents cell division and ultimately leads to cell death. Cyclophosphamide is commonly used in the treatment of various cancers, including leukemia, lymphoma, and solid tumors. Now, let's analyze why the other options are incorrect: A) Methotrexate: Methotrexate is not an alkylating agent. It is a type of antimetabolite drug that inhibits dihydrofolate reductase, interfering with DNA synthesis. B) Cisplatin: Cisplatin is a platinum-containing compound and not an alkylating agent. It works by forming cross-links in DNA, leading to cell death. D) Carmustine: Carmustine, also known as BCNU, is a nitrosourea compound and not an alkylating agent. It interferes with DNA replication and RNA transcription. Educationally, understanding the classification of anticancer drugs based on their mechanisms of action is crucial for pharmacology students and healthcare professionals. Knowing the specific properties of each drug helps in selecting the most appropriate treatment for different types of cancers and understanding potential side effects and interactions. This knowledge is essential for safe and effective medication management in clinical practice.

Correct Answer: A

Rationale: The most likely adverse effect to occur after adding a third drug that acts by decreasing central sympathetic outflow would be severe postural hypotension. This is due to the combined effect of the drugs leading to a significant drop in blood pressure upon standing up, causing dizziness and potential fainting episodes. This adverse effect is commonly associated with antihypertensive medications that affect sympathetic outflow.