Correct Answer: B

Rationale: The correct answer is B. Alcohol is very lipid-soluble and rapidly crosses the blood-brain barrier, leading to its effects on the central nervous system and causing symptoms like sedation and unconsciousness. Choice A is incorrect because alcohol is not water-soluble; it is lipid-soluble. Choice C is incorrect as alcohol does not reverse the transport of substances from the brain. Choice D is incorrect as sedation from alcohol is not a reason to just 'sleep it off' in cases of alcohol poisoning, which can be life-threatening and requires medical attention.

Correct Answer: D

Rationale: The correct answer is D: Docosanol (Abreva). Docosanol is an over-the-counter topical cream commonly used to treat cold sores caused by the herpes simplex virus. It works by inhibiting viral fusion to host cell membranes, reducing the spread of the virus. Ganciclovir (Choice A) is an antiviral medication used for the treatment of cytomegalovirus infections. Valacyclovir (Choice B) and Famciclovir (Choice C) are prescription antiviral medications used to treat herpes simplex virus infections but are not typically available over-the-counter like Docosanol.

Correct Answer: A

Rationale: The correct answer is A. The Climara patch delivers estradiol transdermally, and patients should be instructed to avoid prolonged sun exposure at the patch site due to increased plasma concentrations. Sun exposure can accelerate the absorption of the medication, leading to higher systemic levels than intended. Choices B, C, and D are incorrect because heat at the patch site does not result in pregnancy but may alter absorption rates, there is no direct link between sunlight exposure and breast cancer risk related to this medication, and exposure to cold does not increase effectiveness of the transdermal patch.

Correct Answer: B

Rationale: In an 8-year-old boy with a sex hormone deficiency being treated with testosterone, the appearance of signs of puberty would necessitate stopping the treatment. Testosterone therapy in this case aims to supplement the deficient sex hormones but should not trigger premature puberty. Excessive growth in height (choice A) is not a typical reason to stop testosterone therapy. Recurrent urinary tract infections (choice C) and increased blood pressure (choice D) are not directly related to testosterone therapy in this context.

Correct Answer: B

Rationale: The correct answer is B: 'Use of nitrates.' Sildenafil (Viagra) is contraindicated in patients taking nitrates due to the risk of severe hypotension. Nitrates and sildenafil both cause vasodilation, and their combined use can lead to a dangerous drop in blood pressure. Choices A, C, and D are incorrect because a history of hypertension, recent use of antihypertensive medications, or a history of peptic ulcer disease are not direct contraindications for using sildenafil.