Tick the antibacterial drug – a nitrofurane derivative:

Correct Answer: A

Rationale: Nitrofurantoin is the correct answer because it is a nitrofurane derivative with antibacterial properties, commonly used to treat urinary tract infections. Trimethoprim, Ciprofloxacin, and Nystatin are not nitrofurane derivatives and have different mechanisms of action, making them ineffective for this purpose.

Correct Answer: C

Rationale: The correct answer is C: Increased capacitance of systemic veins. Nitrates cause vasodilation, leading to increased venous capacitance, reducing preload and myocardial oxygen demand. Decreased ejection time (A) and decreased arterial pressure (D) are actually beneficial effects of nitrates, as they reduce cardiac workload. Increased cardiac rate (B) is not a common adverse effect of nitrates in the treatment of exertional angina.

Correct Answer: A

Rationale: The correct answer is A: Inhibition of phosphodiesterase. Milrinone is a phosphodiesterase inhibitor, which increases cAMP levels, leading to enhanced cardiac contractility. This occurs through the inhibition of the breakdown of cAMP, resulting in increased intracellular calcium levels and improved myocardial function. Choice B is incorrect because while protein kinase can increase cytoplasmic Ca2+, it is not the primary mechanism of milrinone's positive inotropic action. Choice C is incorrect as milrinone does not directly inhibit the Ca2+/Na+ exchanger. Choice D is incorrect as activation of phospholipase A2 is not the mechanism through which milrinone exerts its positive inotropic effects.

Correct Answer: D

Rationale: In the context of cardiovascular drugs, understanding the regulation of aldosterone release is crucial. The correct answer is D) Both (b) and (c) because both Angiotensin and Angiotensin III stimulate aldosterone release. Angiotensin, which is converted from Angiotensin I through the action of ACE (Angiotensin-Converting Enzyme), directly stimulates the release of aldosterone from the adrenal cortex. This hormone plays a key role in regulating blood pressure and electrolyte balance in the body. Angiotensin III, a metabolite of Angiotensin II, also has the ability to stimulate aldosterone release. It binds to specific receptors in the adrenal gland, leading to aldosterone secretion. Option A, Angiotensin I, is incorrect because Angiotensin I itself does not directly stimulate aldosterone release. It needs to be converted to Angiotensin II to exert its effects on aldosterone secretion. Option C, Angiotensin III alone, is also incorrect as it is not the sole stimulator of aldosterone release. While Angiotensin III does have some aldosterone-stimulating activity, it is not as potent as Angiotensin II. Understanding the interactions between the renin-angiotensin-aldosterone system and how different components regulate hormone release is essential in pharmacology and clinical practice. This knowledge helps healthcare professionals in managing conditions like hypertension and heart failure effectively by targeting specific points in this pathway with medications like ACE inhibitors or angiotensin receptor blockers.

Correct Answer: C

Rationale: The correct answer to the question "Tolerance to nitroglycerin may be overcome by" is C) Temporarily discontinuing the drug for one or two weeks. Rationale: Nitroglycerin is a vasodilator commonly used in the treatment of angina pectoris. Over time, patients may develop tolerance to its effects, reducing its efficacy. By temporarily discontinuing the drug for a period of one or two weeks, the body can regain its sensitivity to nitroglycerin, allowing it to work effectively again. This break helps to prevent or reverse the development of tolerance. Option A) Initially using the largest safe dose of the drug is incorrect because increasing the dose does not address tolerance but may lead to increased side effects and potential toxicity. Option B) Using other nitrites is not the preferred method to overcome tolerance to nitroglycerin. While other nitrites may have similar effects, discontinuing nitroglycerin is a more direct approach to addressing tolerance. Option D) Use of higher doses is not the best approach as mentioned earlier. Increasing the dose does not reverse tolerance and may exacerbate side effects without addressing the underlying issue of decreased drug effectiveness. Educational Context: Understanding how tolerance develops and strategies to manage it is crucial in pharmacology. Educating healthcare professionals on the mechanisms of drug tolerance and appropriate interventions, such as temporarily discontinuing the medication, ensures safe and effective patient care. By grasping these concepts, healthcare providers can optimize treatment outcomes and prevent potential complications associated with drug tolerance.