Cocaine exerts its central action by:

Correct Answer: C

Rationale: Cocaine exerts its central action by inhibiting dopamine and norepinephrine reuptake. This leads to an accumulation of these neurotransmitters in the synaptic cleft, enhancing their effects. This mechanism results in increased stimulation of the central nervous system, leading to the characteristic effects of cocaine such as increased alertness and euphoria. Choices A and D are incorrect as cocaine does not directly affect phosphodiesterase or serotonin turnover. Choice B is incorrect as while cocaine does increase the release of neurotransmitters, its primary mechanism of action is through reuptake inhibition.

Correct Answer: C

Rationale: The correct answer is C: No-spa. No-spa is the drug that affects the biliary system and relaxes the Oddi sphincter. The Oddi sphincter is a muscular valve that controls the flow of bile and pancreatic juice into the duodenum. No-spa, also known as Drotaverine, is a smooth muscle relaxant that works by inhibiting phosphodiesterase enzyme, leading to relaxation of smooth muscles including the Oddi sphincter. Choices A, B, and D are incorrect as they do not specifically target the biliary system or the Oddi sphincter. Cholosas is a liver protectant, Oxaphenamide is a carbonic anhydrase inhibitor, and Cholenzyme is a combination of digestive enzymes.

Correct Answer: C

Rationale: The correct answer is C: Lidocaine. Lidocaine is favored for digitalis-induced arrhythmias due to its sodium channel blocking properties, which can help stabilize the heart rhythm. Verapamil (A) is a calcium channel blocker and may worsen arrhythmias. Amiodarone (B) is effective for various arrhythmias but may interact with digitalis. Propranolol (D) is a beta-blocker and may not be as effective as lidocaine for digitalis-induced arrhythmias.

Correct Answer: D

Rationale: The correct answer is D, as calcium channel blockers have multiple effects on the cardiovascular system. They reduce peripheral vascular resistance by dilating blood vessels, decrease cardiac contractility and output by blocking calcium entry into cardiac muscle cells, and relieve coronary artery spasm by dilating coronary arteries. Therefore, all of the choices (A, B, and C) are correct effects of calcium channel blockers. The other choices are incorrect because they do not encompass all the effects of calcium channel blockers.

Correct Answer: B

Rationale: The correct answer is B because at low doses, dopamine primarily acts on dopamine receptors, leading to vasodilation of renal and mesenteric vessels. This is known as the renal dose of dopamine. Choices A and C are incorrect because low doses of dopamine do not significantly impact alpha-adrenoreceptors for peripheral vasoconstriction or beta-1 adrenoreceptors for enhancing cardiac output. Choice D is incorrect as dopamine at low doses does not affect all the mentioned receptors simultaneously.