Tick the unwanted effects of fluoroquinolones:

Correct Answer: B

Rationale: The correct answer is B: Headache, dizziness, insomnia. Fluoroquinolones are known to cause central nervous system side effects such as headache, dizziness, and insomnia. These unwanted effects are commonly reported with the use of fluoroquinolones. Hallucinations (choice A) are not typically associated with fluoroquinolones. Hypertension (choice C) is not a common side effect of fluoroquinolones. Immunetoxicity (choice D) is a general term and not a specific unwanted effect of fluoroquinolones. Therefore, choice B is the correct answer due to the known side effects of fluoroquinolones on the central nervous system.

Correct Answer: C

Rationale: Rationale: 1. Digoxin inhibits Na+/K+ ATPase, leading to intracellular Na+ accumulation. 2. Increased intracellular Na+ reduces the activity of Na+/Ca2+ exchanger, causing Ca2+ to remain in the cell. 3. Elevated intracellular Ca2+ levels enhance cardiac contractility, resulting in positive inotropic effects. Summary: A: Closing of calcium channels would decrease Ca2+ influx, contrary to the inotropic effect. B: Increased release of Ca2+ from the sarcoplasmic reticulum is not the primary mechanism of digoxin's action. D: Activation of the Ca2+/Na+ exchanger would lead to Ca2+ extrusion, opposing the inotropic effect.

Correct Answer: G

Rationale: Ibutilide is the correct choice as it is a class III antiarrhythmic drug used for converting atrial fibrillation/flutter. It has a rapid onset of action and is effective in patients with normal renal function. Amiodarone (B) is a class III antiarrhythmic but is not first-line due to its potential side effects. Procainamide (C) is a class Ia antiarrhythmic and may not be suitable for this patient. Sotalol (D) is a class III antiarrhythmic but has a higher risk of proarrhythmia compared to ibutilide.

Correct Answer: A

Rationale: In this question, the correct answer is A) Digoxin. Digoxin is a cardiac glycoside that acts by inhibiting the sodium-potassium pump, leading to an increase in intracellular calcium levels. This increase in calcium enhances cardiac contractility, making the heart muscle more efficient at pumping blood. Digoxin also predictably prolongs the PR interval by slowing down the conduction of electrical impulses through the atrioventricular (AV) node. This effect is important to note as it can be seen on an electrocardiogram (ECG) when monitoring patients on digoxin therapy. Now, let's discuss why the other options are incorrect: - B) Lidocaine is a local anesthetic and antiarrhythmic drug that primarily works by blocking sodium channels in the heart to prevent abnormal electrical activity. It does not affect the PR interval or increase cardiac contractility. - C) Propranolol is a beta-blocker that decreases heart rate and blood pressure by blocking beta-adrenergic receptors. It does not predictably prolong the PR interval or increase cardiac contractility. - D) Quinidine is an antiarrhythmic medication that works by blocking sodium and potassium channels in the heart. While it can prolong the QT interval on an ECG, it does not specifically prolong the PR interval or increase cardiac contractility like digoxin. In an educational context, understanding the effects of different cardiovascular drugs on the heart's electrical conduction system and contractility is crucial for healthcare professionals, especially those working in cardiology or critical care settings. Recognizing the unique actions of each medication helps in making informed decisions regarding treatment options and monitoring for potential side effects or complications.

Correct Answer: B

Rationale: The correct statement about the action of nitrates on coronary vessels is option B) They preferentially dilate conducting arteries without affecting resistance arterioles. This is the right answer because nitrates primarily act by dilating veins, which reduces preload and consequently decreases cardiac oxygen demand. This dilation also affects conducting arteries, like the large epicardial coronary arteries, leading to increased blood flow to the myocardium. Option A is incorrect because nitrates do not increase total coronary flow significantly; instead, they redistribute blood flow within the coronary circulation. Option C is incorrect because nitrates do not selectively dilate autoregulatory arterioles; their effect is more prominent on conducting arteries. Option D is incorrect because nitrates increase subendocardial blood flow more than subepicardial blood flow due to their preferential dilation of larger coronary arteries. From an educational perspective, understanding the mechanism of action of nitrates on coronary vessels is crucial for healthcare professionals managing patients with cardiovascular diseases like angina pectoris. Knowing how nitrates affect coronary circulation helps in optimizing treatment strategies and ensuring better patient outcomes. This knowledge also forms the basis for further learning about the pharmacological management of cardiovascular conditions.