The nurse administers 50 mg of a drug at 6:00 AM that has a half-life of 8 hours. What time will it be when 25 mg of the drug has been eliminated from the body?

Correct Answer: C

Rationale: To determine when 25 mg of the drug will be eliminated, we first calculate the time it takes for half the initial dose to be eliminated, which is 8 hours. So, by 2:00 PM (8 hours after administration), 25 mg will be eliminated. This is because half of the initial 50 mg (25 mg) would have been metabolized by then. Therefore, the correct answer is C. Choice A (8:00 AM) is incorrect because it is too early for 25 mg to be eliminated. Choice B (11:00 AM) is incorrect because it is only 5 hours after administration, not enough time for 25 mg to be eliminated. Choice D (6:00 PM) is incorrect because it is too late, as 25 mg would have been eliminated by 2:00 PM.

Correct Answer: D

Rationale: The correct answer is D: Amphotericin B and fluconazole. Amphotericin B is an antifungal medication used for severe fungal infections, while fluconazole is commonly used for less severe fungal infections. The combination of these two drugs would be most likely given to treat a severe fungal infection that requires immediate and potent treatment. A: Amphotericin B and terbinafine - Terbinafine is primarily used to treat fungal infections of the skin and nails, not severe systemic fungal infections. B: Caspofungin and griseofulvin - Griseofulvin is used to treat superficial fungal infections like ringworm, while caspofungin is used for systemic fungal infections. C: Caspofungin and metronidazole - Metronidazole is an antibiotic used to treat bacterial and parasitic infections, not fungal infections.

Correct Answer: A

Rationale: Step 1: Chloroquine is a known antimalarial drug that targets Plasmodium species by inhibiting their ability to replicate within red blood cells. Step 2: Amoxicillin is an antibiotic effective against bacteria, not parasites like Plasmodium. Step 3: Levofloxacin and Ciprofloxacin are also antibiotics that target bacterial infections, not malaria caused by Plasmodium species.

Correct Answer: A

Rationale: The correct answer is A: Binding to opioid receptors in the brain. Oxycodone is an opioid analgesic that works by binding to opioid receptors in the brain, spinal cord, and other parts of the body to reduce pain perception. Opioid receptors are primarily located in the central nervous system and play a crucial role in pain modulation. By binding to these receptors, oxycodone can produce analgesic effects. Choices B, C, and D are incorrect: B: Inhibiting the reuptake of serotonin and norepinephrine is a mechanism of action for some antidepressants, not opioids like oxycodone. C: Inhibiting prostaglandin synthesis is a mechanism of action for nonsteroidal anti-inflammatory drugs (NSAIDs), not opioids like oxycodone. D: Increasing dopamine release is a mechanism of action for certain stimulant medications, not opioids like oxycodone.

Correct Answer: B

Rationale: The correct answer is B: Rifampin. Rifampin is used to treat tuberculosis by inhibiting bacterial RNA synthesis through binding to the beta subunit of bacterial RNA polymerase. This inhibits transcription and ultimately leads to bacterial cell death. Isoniazid (choice A) targets mycolic acid synthesis, not RNA synthesis. Amoxicillin (choice C) and Azithromycin (choice D) are antibiotics that work by interfering with bacterial cell wall synthesis or protein synthesis, respectively, not RNA synthesis. Thus, Rifampin is the correct choice for treating tuberculosis by inhibiting bacterial RNA synthesis.