Tick the drug which is effective against mycobacteria only:

Correct Answer: A

Rationale: Step-by-step rationale: 1. Isoniazid is a first-line drug specifically used to treat mycobacterial infections like tuberculosis. 2. It works by inhibiting cell wall synthesis of mycobacteria. 3. Streptomycin, Rifampin, and Kanamycin are also used for mycobacterial infections, but they are effective against a broader range of bacteria. 4. Streptomycin targets protein synthesis, Rifampin inhibits RNA synthesis, and Kanamycin disrupts protein synthesis. 5. Therefore, choice A, Isoniazid, is the correct answer as it targets mycobacteria specifically.

Correct Answer: B

Rationale: Step-by-step rationale: 1. Vincristine is a vinca alkaloid, not a nitrosourea derivative. 2. Carmustine, Lomustine, and Semustine are all nitrosourea derivatives. 3. Therefore, the correct answer is B (Vincristine). Summary: Vincristine is not a nitrosourea derivative, unlike Carmustine, Lomustine, and Semustine.

Correct Answer: C

Rationale: The correct answer is C: Flecainide. Flecainide is a class I antiarrhythmic drug that can cause proarrhythmia, leading to exacerbation of arrhythmias and increased risk of sudden cardiac death. It is known to cause ventricular tachycardia and ventricular fibrillation, which could manifest as the patient's signs and symptoms. Mexiletine (A) and Lidocaine (D) are also class I antiarrhythmics, but they are less likely to cause the described symptoms compared to Flecainide. Sotalol (B) is a class III antiarrhythmic drug and would not typically present with the same signs and symptoms as Flecainide.

Correct Answer: C

Rationale: The correct answer is C: Propranolol. Propranolol is a beta-blocker commonly used for hypertension. In overdose, it can lead to bradycardia, hypotension, and cardiovascular collapse, which align with the signs and symptoms of the patient in question. Ipratropium (A) is an anticholinergic used for COPD, unlikely to cause the described symptoms. Adenosine (B) is a medication used for supraventricular tachycardia and wouldn't result in the observed effects. Lidocaine (D) is a local anesthetic and not associated with the cardiovascular symptoms presented by the patient.

Correct Answer: A

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