Unwanted effect of plicamycin (formerly mithramycin) is:

Correct Answer: B

Rationale: Step 1: Plicamycin inhibits RNA synthesis in cancer cells, leading to myelosuppression. Step 2: Myelosuppression results in decreased production of blood cells, causing anemia, thrombocytopenia, and neutropenia. Step 3: Diarrhea is not a common adverse effect of plicamycin. Step 4: Nephrolithiasis and metastatic calcifications are not directly associated with plicamycin use.

Correct Answer: D

Rationale: The correct answer is D. Sulfonamides inhibit folic acid synthesis, which is essential for the growth of bacteria, Chlamydia, Actinomyces, and some protozoa. This mechanism makes them effective against all the mentioned microorganisms. Choice A is incorrect because it does not include protozoa. Choice B is incorrect because sulfonamides are effective against Actinomyces. Choice C is incorrect because sulfonamides are not effective against all protozoa.

Correct Answer: B

Rationale: The correct answer is B: Diloxanide. Diloxanide is the drug of choice for treating the asymptomatic intestinal form of amebiasis because it acts specifically against the trophozoites in the lumen of the intestine without affecting the cysts. Chloroquine (A) is used for malaria, emetine (C) is used for invasive amebiasis, and doxycycline (D) is an antibiotic not typically used for amebiasis.

Correct Answer: B

Rationale: The correct answer is B: Doxorubicin. Doxorubicin is an antibiotic commonly used in cancer chemotherapy to treat various types of cancer. It works by inhibiting DNA and RNA synthesis in cancer cells, leading to cell death. Cytarabine (A) is an antimetabolite used in leukemia treatment, not an antibiotic for cancer chemotherapy. Gentamycin (C) is an aminoglycoside antibiotic used for bacterial infections, not cancer treatment. Etoposide (D) is a topoisomerase inhibitor used in cancer chemotherapy but is not classified as an antibiotic.

Correct Answer: B

Rationale: The correct answer is B: Amiodarone. Amiodarone is not commonly used as an anticonvulsant; it is primarily used as an antiarrhythmic medication to treat various types of irregular heart rhythms. Adenosine is used to treat supraventricular tachycardia, not seizures. Diltiazem is a calcium channel blocker used for hypertension and arrhythmias, not seizures. Esmolol is a beta-blocker primarily used for controlling heart rate in certain conditions, not seizures. Therefore, Amiodarone is the most appropriate choice for treating generalized tonic-clonic seizures.