Tick the antimycobacterial drug belonging to first-line agents:

Correct Answer: B

Rationale: The correct answer is B: Isoniazid. It is a first-line antimycobacterial drug used for treating tuberculosis. It targets the mycobacterial cell wall synthesis, specifically inhibiting mycolic acid production. This makes it effective against Mycobacterium tuberculosis. PAS (A) is a second-line drug with a different mechanism. Kanamycin (C) is also a second-line drug used for drug-resistant TB. Pyrazinamide (D) is a first-line drug, but it works by a different mechanism compared to isoniazid.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Cytoprotectors help protect healthy cells from damage caused by cancer treatment. Bone marrow growth factors aid in stimulating the production of blood cells, which can be suppressed during cancer treatment. Antimetastatic agents help prevent the spread of cancer to other parts of the body. Therefore, all these groups of drugs are used as subsidiary medicines in cancer treatment to support the primary treatment and manage side effects. Choices A, B, and C are incorrect individually because each group plays a specific role in supporting cancer treatment, making the combination of all three necessary for comprehensive care.

Correct Answer: D

Rationale: Step 1: Identify the patient's condition as ventricular arrhythmia. Step 2: Choose a drug effective for ventricular arrhythmias, like Lidocaine. Step 3: Lidocaine is a class Ib antiarrhythmic drug that acts quickly on ventricular tissue. Step 4: Sotalol (A) is a non-selective beta blocker, not ideal for ventricular arrhythmias. Step 5: Flecainide (B) is a class Ic antiarrhythmic drug more suitable for supraventricular arrhythmias. Step 6: Mexiletine (C) is a class Ib antiarrhythmic, but lidocaine is preferred for acute ventricular arrhythmias.

Correct Answer: D

Rationale: The correct answer is D: Amiodarone. Amiodarone is a potent antiarrhythmic drug commonly used to prevent fibrillatory episodes like atrial fibrillation. It has a broad spectrum of action, affecting multiple ion channels to stabilize cardiac rhythm. Mexiletine (A) is used for ventricular arrhythmias, not fibrillatory episodes. Sotalol (B) is also used for ventricular arrhythmias and can actually increase the risk of torsades de pointes in patients with atrial fibrillation. Quinidine (C) is an older antiarrhythmic that is less commonly used due to its potential for proarrhythmic effects.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.