The following tetracycline has the potential to cause vestibular toxicity: *

Correct Answer: C

Rationale: The correct answer is C, Minocycline. Minocycline has a higher potential for vestibular toxicity compared to other tetracyclines due to its greater lipid solubility, leading to increased penetration of the blood-brain barrier and inner ear. This can result in dizziness, vertigo, and imbalance. Choice A, Doxycycline, is less likely to cause vestibular toxicity since it has lower lipid solubility and reduced penetration into the inner ear. Choice B, Oxytetracycline, and Choice D, Demeclocycline, also have lower potential for vestibular toxicity compared to Minocycline due to similar reasons. Overall, Minocycline stands out as the correct answer due to its unique pharmacokinetic properties that predispose it to vestibular toxicity.

Correct Answer: A

Rationale: Step-by-step rationale for choice A (Ganciclovir) being the correct answer: 1. Ganciclovir is a nucleoside analog that inhibits CMV DNA synthesis. 2. It is specifically approved for the treatment of CMV retinitis in immunocompromised patients. 3. Ganciclovir has a high specificity for CMV, making it an effective antiviral agent against CMV. Summary of why the other choices are incorrect: - Choice B (Foscarnet) is also active against CMV but is not as commonly used as Ganciclovir. - Choice C (Acyclovir) is not effective against CMV as it primarily targets herpes simplex virus and varicella-zoster virus. - Choice D ( ) is an incomplete choice and does not correspond to any known antiviral agent.

Correct Answer: B

Rationale: The correct answer is B: Lamivudine and zidovudine. Combivir is a combination therapy that consists of these two drugs. Lamivudine and zidovudine work together to inhibit the replication of the HIV virus. Lamivudine is a nucleoside reverse transcriptase inhibitor, while zidovudine is a nucleoside analog reverse transcriptase inhibitor. Both drugs target different stages of the HIV life cycle, making them effective when used in combination. Choice A (Lamivudine and stavudine) is incorrect because stavudine is not part of the Combivir combination therapy. Choice C (Abacavir and zidovudine) is incorrect because abacavir is not included in Combivir. Choice D (Abacavir and stavudine) is incorrect because stavudine is not part of the Combivir combination therapy.

Correct Answer: B

Rationale: The correct answer is B: Azithromycin. It has a long half-life allowing for once-daily dosing for 3 days. Azithromycin is effective against common ENT, respiratory, and genital infections. Rationale: A: Erythromycin requires more frequent dosing due to shorter half-life. C: Clarithromycin is not typically given once a day for 3 days. D: Roxithromycin is less commonly used for these infections and has a shorter half-life.

Correct Answer: A

Rationale: The correct answer is A: Streptomycin. Streptomycin binds to the S12 ribosomal subunit, inhibiting protein synthesis in Mycobacterium tuberculosis. It is effective against drug-resistant tuberculosis and is used as an injectable drug. Streptomycin can cause ototoxicity and nephrotoxicity as side effects. Choice B: Ethambutol primarily inhibits cell wall synthesis and can cause optic neuritis. Choice C: Isoniazid inhibits mycolic acid synthesis and can cause hepatotoxicity. Choice D: Rifampicin inhibits DNA-dependent RNA polymerase and can cause hepatotoxicity and drug interactions.