Tick praziquantel mechanism of action:

Correct Answer: C

Rationale: The correct answer is C because praziquantel increases cell membrane permeability for calcium, leading to paralysis, dislodgement, and death of helminthes. This mechanism disrupts the helminth's ability to maintain membrane integrity and homeostasis, ultimately causing their demise. A is incorrect as praziquantel does not block acetylcholine transmission. B is incorrect because praziquantel does not inhibit microtubule synthesis or impair glucose uptake. D is incorrect as praziquantel does not inhibit oxidative phosphorylation in helminthes.

Correct Answer: C

Rationale: Step-by-step rationale for why choice C (Adenosine) is correct: 1. Adenosine is used for supraventricular tachycardia due to its ability to slow conduction through the AV node. 2. Mexiletine and Lidocaine are sodium channel blockers used for ventricular arrhythmias, not supraventricular tachycardia. 3. Amiodarone is a broad-spectrum antiarrhythmic used for various types of arrhythmias, not specific to supraventricular tachycardia. Summary: Adenosine is the correct answer because of its specific mechanism of action in treating supraventricular tachycardia. Mexiletine, Lidocaine, and Amiodarone are used for different types of arrhythmias, making them incorrect choices.

Correct Answer: C

Rationale: The correct answer is C: Adenosine. Adenosine is commonly used for cardioversion of supraventricular tachycardias like atrial flutter. It works by blocking the AV node transiently, allowing the sinus node to regain control of the heart rhythm. Mexiletine (A) and Lidocaine (B) are primarily used for ventricular arrhythmias, not atrial flutter. Amiodarone (D) is often used for atrial fibrillation, not specifically atrial flutter.

Correct Answer: B

Rationale: In this question, the correct answer is B) Hydralazine and isosorbide dinitrate. Hydralazine is a vasodilator that primarily acts on arterioles, reducing afterload by decreasing systemic vascular resistance. Isosorbide dinitrate is a nitrate that primarily acts on veins, reducing preload by decreasing venous return to the heart. When these two drugs are used together, they effectively reduce both preload (amount of blood returning to the heart) and afterload (resistance the heart has to pump against). Now, let's analyze why the other options are incorrect: A) Nitroglycerin and isosorbide dinitrate: While both are nitrates that primarily reduce preload, nitroglycerin acts on veins more than arteries, and therefore, does not significantly reduce afterload like hydralazine does. C) Captopril and methyldopa: Captopril is an ACE inhibitor that reduces afterload, but methyldopa is a centrally acting alpha-2 agonist that primarily reduces blood pressure through a different mechanism and does not directly reduce preload or afterload significantly when used in combination with captopril. D) Prazosin and angiotensin II: Prazosin is an alpha-1 adrenergic blocker that reduces afterload, but angiotensin II is a vasoconstrictor that increases afterload, so the combination would not effectively reduce both preload and afterload. Educational Context: Understanding how different drugs affect preload and afterload is crucial in pharmacology, especially in the treatment of cardiovascular diseases like heart failure and hypertension. By knowing the mechanisms of action of different drug classes, healthcare professionals can make informed decisions about selecting the most appropriate medications for patients based on their clinical presentation and needs.

Correct Answer: A

Rationale: In pharmacology, understanding the effects of aspirin on cardiovascular health is crucial. In this scenario, the correct answer is A) Is of benefit in patients with unstable angina. Aspirin, in small doses (50 to 150 mg per day), is commonly used in the management of cardiovascular conditions due to its antiplatelet effects. In unstable angina, where there is a risk of clot formation leading to a heart attack, aspirin helps prevent platelet aggregation, reducing the chances of a clot blocking a coronary artery. Option B) Has thrombolytic action is incorrect because aspirin is not a thrombolytic agent. Thrombolytics work by breaking down existing clots, whereas aspirin prevents clot formation. Option C) PREFerentially inhibits prostacyclin synthetase enzyme is incorrect as aspirin actually inhibits cyclooxygenase enzymes, particularly COX-1, which is involved in the production of thromboxane A2, a potent platelet aggregator. Option D) MAY Alleviate the need for Verapamil in variant angina is incorrect because Verapamil is a calcium channel blocker used to prevent and treat variant angina by dilating coronary arteries and reducing the workload of the heart, while aspirin primarily works on platelet inhibition rather than vasodilation. Educationally, this question highlights the importance of understanding the specific actions and uses of medications in cardiovascular pharmacology. It emphasizes the role of aspirin as an antiplatelet agent in preventing clot formation, particularly in conditions like unstable angina where there is a high risk of clot-related complications. Understanding the mechanisms of action of drugs is crucial for making informed clinical decisions in managing cardiovascular diseases.