Tick the drug belonging to antibiotics-macrolides:

Correct Answer: C

Rationale: The correct answer is C: Erythromycin. Erythromycin is a macrolide antibiotic due to its macrocyclic lactone ring structure. Macrolides inhibit bacterial protein synthesis by binding to the 50S ribosomal subunit. Neomycin (A) is an aminoglycoside, Doxycycline (B) is a tetracycline, and Cefotaxime (D) is a cephalosporin, none of which are macrolides. Thus, Erythromycin is the only drug among the options that belongs to the antibiotics-macrolides category.

Correct Answer: B

Rationale: The correct answer is B because piperazine works by blocking acetylcholine transmission at the myoneural junction, leading to paralysis of helminthes. This impairs the ability of the worms to move and causes them to be expelled from the body. The other choices are incorrect because: A: Inhibiting microtubule synthesis and impairing glucose uptake is not the mechanism of action of piperazine. C: Inhibiting oxidative phosphorylation is not how piperazine works. D: Increasing cell membrane permeability for calcium leading to paralysis and death is not the mechanism of action of piperazine.

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.