Tick the drug, inhibiting viral proteases:

Correct Answer: C

Rationale: Step-by-step rationale: 1. Saquinavir is a protease inhibitor used in the treatment of HIV by blocking viral proteases essential for viral replication. 2. Rimantadine is an antiviral drug used for influenza A virus, not inhibiting viral proteases. 3. Acyclovir is an antiviral drug for herpes simplex virus, working by inhibiting viral DNA synthesis, not proteases. 4. Zalcitabine is a nucleoside analog used for HIV, but it inhibits reverse transcriptase, not viral proteases. Summary: Saquinavir is the correct answer as it specifically inhibits viral proteases crucial for viral replication. The other choices target different viral enzymes or processes, making them incorrect for this question.

Correct Answer: A

Rationale: The correct answer is A: Severe postural hypotension. Adding a third drug that decreases central sympathetic outflow (possibly a centrally acting alpha-2 adrenergic agonist) can lead to a sudden drop in blood pressure upon standing, causing postural hypotension. This occurs due to decreased sympathetic tone leading to vasodilation and reduced vascular tone. This effect is more likely to occur shortly after initiating therapy with the new drug. Choice B: Megaloblastic anemia is not a common adverse effect of drugs that decrease sympathetic outflow. Choice C: Palpitations are not typically associated with drugs that decrease sympathetic outflow. Choice D: Pronounced sedation is not a common side effect of centrally acting sympatholytic drugs.

Correct Answer: D

Rationale: In this question, the correct answer is D) Verapamil. Verapamil is a calcium channel blocker that decreases heart rate by inhibiting calcium ion influx, leading to decreased myocardial oxygen demand. This effect helps in the treatment of angina by reducing the workload of the heart and preventing vasospastic angina attacks. Option A) Isosorbide dinitrate and option C) Nitroglycerin are nitrates that primarily work by dilating blood vessels to increase oxygen supply to the heart muscle. While they are effective in treating angina, they do not consistently decrease heart rate like verapamil. Option B) Nifedipine is a calcium channel blocker like verapamil, but it mainly acts on the peripheral vasculature to reduce blood pressure and coronary vasospasm. It does not have as significant an effect on heart rate as verapamil. Educationally, understanding the mechanisms of action of different cardiovascular drugs is crucial for prescribing the most appropriate treatment for patients with angina. Verapamil's specific effect on heart rate makes it a suitable choice for patients with angina who also require heart rate control. This knowledge helps healthcare providers tailor treatment plans to individual patient needs effectively.

Correct Answer: D

Rationale: Quinidine, a class I antiarrhythmic drug, is primarily used for preventing recurrences of atrial and ventricular extrasystoles and tachycardias. This is because quinidine works by blocking sodium channels in cardiac cells, which helps to stabilize the heart's electrical activity and prevent abnormal rhythms. Option A, converting atrial fibrillation to sinus rhythm, is not the primary use of quinidine. Drugs like amiodarone are more commonly used for this purpose due to their efficacy and safety profile. Option B, controlling ventricular rate in atrial flutter, is typically managed with drugs like beta-blockers or calcium channel blockers, which are more effective in controlling heart rate in atrial flutter. Option C, terminating ventricular tachycardia, is usually handled with antiarrhythmic medications like procainamide or amiodarone, as these are more effective in quickly terminating ventricular tachycardia. In an educational context, understanding the specific indications of each cardiovascular drug is crucial for effective pharmacological management of cardiac arrhythmias. Knowing the primary uses of medications like quinidine helps healthcare professionals make informed decisions in selecting the most appropriate treatment for their patients based on the type of arrhythmia present.

Correct Answer: D

Rationale: The correct answer to the question "Which of the following is the longest-acting nitrate?" is D) Pentaerythritol tetranitrate. This is because pentaerythritol tetranitrate, also known as PETN, has a longer duration of action compared to the other options. Glyceryl trinitrate (option A) is a short-acting nitrate commonly used for the acute relief of angina symptoms. Ethyl tetranitrate (option B) and octyl nitrite (option C) are not commonly used nitrates in clinical practice and do not have the same duration of action as pentaerythritol tetranitrate. In an educational context, understanding the duration of action of different nitrates is crucial for healthcare professionals, especially those working with patients who have cardiovascular conditions like angina. Knowing which nitrate has a longer duration of action can help in selecting the most appropriate medication for a patient based on their specific needs and condition. This knowledge can also aid in preventing potential drug interactions and adverse effects by ensuring the proper timing and dosing of medications.