What is the drug of choice for ringworm infection ?: *

Correct Answer: A

Rationale: The correct answer is A: Griseofulvin. Griseofulvin is the drug of choice for ringworm infections due to its effectiveness against dermatophytes. It works by inhibiting fungal cell division. Amphotericin B is used for systemic fungal infections, not ringworm. Nystatin is used for yeast infections, not ringworm. Neomycin is an antibiotic and is not effective against fungal infections like ringworm.

Correct Answer: B

Rationale: The correct answer is B: Ciprofloxacin. Ciprofloxacin is a fluoroquinolone antibiotic that inhibits bacterial DNA gyrase, an enzyme crucial for bacterial DNA replication and repair. By interfering with DNA function, it disrupts bacterial growth and can effectively treat most cases of uncomplicated gonorrhea. Rationale: A: Chloramphenicol inhibits protein synthesis, not DNA function. C: Streptomycin inhibits protein synthesis by binding to the bacterial ribosome. D: Erythromycin also inhibits bacterial protein synthesis and is not primarily targeted at DNA function.

Correct Answer: C

Rationale: The correct answer is C: Suramin. Suramin is the drug of choice for treating Chaga's disease caused by Trypanosoma cruzi. It is a specific drug that targets the parasite responsible for the disease. Nifurtimox is used for acute Chaga's disease, not chronic cases like in this patient. Metronidazole is not effective against Trypanosoma cruzi. Chloroquine is used for treating malaria, not Chaga's disease. Therefore, the most appropriate drug for this patient is Suramin.

Correct Answer: B

Rationale: The main reason for using combination therapy in tuberculosis treatment is to delay or prevent the emergence of resistance. By using multiple drugs that target different aspects of the bacteria's life cycle, it becomes harder for the bacteria to develop resistance to all drugs simultaneously. This helps to ensure that the treatment remains effective in the long term. Explanation for other choices: A: While combination therapy can sometimes help reduce side effects by using lower doses of each drug, the primary reason for using it in tuberculosis treatment is to prevent resistance, not side effects. C: While combination therapy can increase antimycobacterial activity, the main goal is to prevent resistance, not to enhance the drugs' effects. D: Providing prophylaxis against other bacterial infections is not the main reason for using combination therapy in tuberculosis treatment; the focus is on preventing resistance.

Correct Answer: B

Rationale: The correct answer is B. Alprostadil is a prostaglandin E1 analogue that works by increasing cyclic guanosine monophosphate (cGMP) levels. This leads to smooth muscle relaxation and vasodilation, which helps in treating conditions like erectile dysfunction. Choice A is incorrect because alprostadil does not primarily increase cyclic adenosine monophosphate (cAMP). Choice C is incorrect as there is no known mechanism of action involving PD for alprostadil. Choice D is an incomplete option and not a valid answer.