The property of prolonged theophyllines is the prevention of night asthmatic attacks. It’s:

Correct Answer: A

Rationale: The correct answer is A because theophyllines are bronchodilators that help relax the muscles in the airways, making it easier to breathe. By preventing airway constriction, theophyllines can indeed help prevent night asthmatic attacks. Choice B is incorrect because the statement is true. Choice C is incorrect because not all options are correct - only option A is. Choice D is incorrect because the statement is true.

Correct Answer: C

Rationale: The correct answer is C. Type III phosphodiesterase inhibitors increase cAMP levels in cardiac myocytes, leading to positive inotropic and vasodilatory effects, reducing afterload. They are associated with the risk of cardiac arrhythmias due to their effects on cardiac contractility. However, they do not show significant cross-tolerance with beta-receptor agonists, as they act via a different mechanism. Therefore, choice C is incorrect.

Correct Answer: D

Rationale: Step 1: Identify the specific bradycardic drug among the choices. Step 2: Atenolol is a beta-blocker known to decrease heart rate. Step 3: Bradycardia is defined as a heart rate <60 bpm. Step 4: Atenolol is commonly used to treat angina and hypertension. Step 5: Therefore, the correct answer is C: Atenolol, as it specifically decreases heart rate. Summary: A: Dipyridamole - antiplatelet, not known for bradycardic effects. B: Validol - used for angina relief, not a bradycardic agent. C: Atenolol - beta-blocker, specific bradycardic drug. D: Alinidine - antiarrhythmic agent, not primarily used for bradycardia.

Correct Answer: B

Rationale: The correct answer is B because Nimodipine and Cinnarizine are calcium channel blockers that affect brain blood flow by dilating cerebral blood vessels. Nimodipine specifically acts on cerebral arteries, while Cinnarizine works by reducing the influx of calcium ions into smooth muscle cells of the brain vasculature. Choice A, Aminalon and Picamilon, are not calcium channel blockers and do not directly influence brain blood flow. Choice C, Heparin and Warfarin, are anticoagulants and do not have a direct effect on brain blood flow through calcium channel blockade. Choice D, Vinpocetine and Nicergoline, are vasodilators that improve cerebral blood flow, but they do not act as calcium channel blockers.

Correct Answer: B

Rationale: Insulin is a polypeptide hormone, and as a protein-based molecule, it is susceptible to degradation by gastric juice, making option B correct. Gastric juice contains enzymes like pepsin that break down proteins. Option A is incorrect because polypeptides are not resistant to destruction by gastric juice. Option C is incorrect as insulin is indeed a polypeptide. Option D is incorrect as insulin is not immediately metabolized by cellular enzymes; instead, it plays a crucial role in regulating glucose metabolism.