Clavulanic acid is combined with amoxicillin because: *

Correct Answer: A

Rationale: The correct answer is A because clavulanic acid acts as a beta-lactamase inhibitor, protecting amoxicillin from being destroyed by beta-lactamase enzymes produced by bacteria. This allows amoxicillin to effectively kill the bacteria. Choices B, C, and D are incorrect because clavulanic acid does not prevent renal excretion of amoxicillin, destroy bacteria directly, or counteract adverse effects of amoxicillin. The primary purpose of combining clavulanic acid with amoxicillin is to enhance amoxicillin's effectiveness by preventing its degradation by bacterial enzymes.

Correct Answer: A

Rationale: The correct answer is A: Nausea and vomiting. Oral ampicillin commonly causes gastrointestinal side effects such as nausea and vomiting due to its impact on the gut flora. This side effect is a result of the antibiotic's mechanism of action and is well-documented in clinical practice. Choices B, C, and D are incorrect as loose bowel movements, constipation, and urticaria are not typically associated with oral ampicillin use.

Correct Answer: C

Rationale: The correct answer is C: Interaction with the viral M2 protein. Amantadine blocks the M2 ion channel of the influenza A virus, preventing the release of viral RNA into the host cell. This inhibits the viral replication process. Option A is incorrect as amantadine does not target viral protease enzymes. Option B is incorrect as amantadine does not inhibit viral RNA-mediated DNA synthesis, which is a process specific to retroviruses. Option D is incorrect as amantadine does not interact with virus-directed thymidine kinase, which is involved in the activation of certain antiviral medications.

Correct Answer: B

Rationale: The correct answer is B: Nevirapine. Nevirapine is a non-nucleoside reverse transcriptase inhibitor (NNRTI) that directly inhibits HIV-reverse transcriptase without needing intracellular activation. It binds directly to the enzyme's active site, preventing the conversion of viral RNA to DNA. Rationale: 1. Nelnavir (A) is a protease inhibitor that works by blocking the protease enzyme needed for viral replication, not reverse transcriptase inhibition. 2. Stavudine (C) and Didanosine (D) are nucleoside reverse transcriptase inhibitors (NRTIs) that require intracellular phosphorylation to become active, unlike Nevirapine. In summary, Nevirapine is the correct answer as it directly inhibits HIV-reverse transcriptase without needing intracellular activation, distinguishing it from the other choices which belong to different drug classes or require intracellular phosphorylation.

Correct Answer: C

Rationale: Rationale for Correct Answer (C): 1. Zidovudine is a nucleoside reverse transcriptase inhibitor (NRTI) used in the treatment of HIV. 2. Zidovudine is indeed converted by cellular enzymes to its active form, zidovudine diphosphate. 3. Zidovudine diphosphate inhibits the reverse transcriptase enzyme, preventing viral DNA replication in HIV-infected cells. 4. This mechanism of action is crucial in reducing viral load and slowing disease progression in HIV patients. Summary of Incorrect Choices: A: Incorrect. While Zidovudine is used in combination therapy for HIV, it is not typically an alternative initial treatment. B: Incorrect. Zidovudine can be used to prevent mother-to-child transmission of HIV, but it is not its primary indication. D: Incorrect. Peripheral neuropathy is not a specific adverse reaction to Zidovudine; rather, it is more commonly associated with