Correct Answer: B

Rationale: In patients with chronic renal failure, especially in older adults, dosages of medications excreted renally need to be adjusted based on kidney function. Acyclovir is primarily eliminated by the kidneys, so in a patient with chronic renal failure, the dose would need to be smaller to prevent drug accumulation and toxicity. Choice A is incorrect because the dose adjustment is more related to the patient's kidney function than the presence of herpes simplex. Choice C is incorrect because the type of herpes infection does not determine the dose adjustment for acyclovir. Choice D is incorrect as the creatinine clearance is a more accurate measure of kidney function compared to creatinine levels.

Correct Answer: D

Rationale: The correct answer is D. Sildenafil (Viagra) should not be taken with nitrates due to the risk of severe hypotension. Nitrates can potentiate the hypotensive effects of sildenafil, leading to a dangerous drop in blood pressure. Choice A is incorrect because sudden hearing loss is a rare but serious side effect associated with sildenafil, not a common side effect. Choice B is not the most important information related to sildenafil use. While it is generally recommended not to exceed one dose per day, the interaction with nitrates is more critical. Choice C is also important to consider as high-fat meals can delay the onset of action of sildenafil, but it is not as crucial as avoiding nitrates.

Correct Answer: B

Rationale: Tetanus toxoid should be administered every 10 years to ensure continued protection against tetanus infection. The correct answer is 'Every 10 years.' Choice A ('Every year') is incorrect as the frequency is too frequent. Choice C ('Every 2 years') is incorrect as it is too frequent for tetanus toxoid administration. Choice D ('Every 5 years') is incorrect as it does not align with the recommended interval for tetanus toxoid booster doses.

Correct Answer: B

Rationale: The correct answer is B: Terbinafine (Lamisil). Terbinafine is commonly used to treat onychomycosis, a fungal infection of the toenails or fingernails. It works by stopping the growth of the fungus. Micafungin (Mycamine) is an antifungal medication used for different types of fungal infections but is not typically used to treat onychomycosis. Voriconazole (Vfend) is another antifungal medication used for specific fungal infections, but it is not a first-line treatment for onychomycosis. Fluconazole (Diflucan) is also an antifungal medication, but it is more commonly used for yeast infections and may not be as effective for treating onychomycosis compared to terbinafine.

Correct Answer: A

Rationale: The correct answer is A, 'Physiologic.' Physiologic atrophy is a normal part of development, like the reduction in thymus size during childhood. Pathologic atrophy (choice B) refers to tissue wasting due to disease, not a normal process like the reduction in thymus size. Disuse atrophy (choice C) results from a lack of physical activity or stimulation, which is not the case with thymus size reduction. Neurogenic atrophy (choice D) is caused by damage to or diseases of the nerves supplying the muscles, not related to the thymus size reduction seen in childhood.