Which of the following statements about bioavailability is true?

Correct Answer: A

Rationale: The correct answer is A because bioavailability is crucial for drugs with narrow therapeutic ranges or sustained release mechanisms as it determines the amount of the drug that reaches the systemic circulation. Choice B is incorrect because different brands of a drug can have varying bioavailability due to differences in formulations. Choice C is incorrect because the frequency of drug administration does not necessarily correlate with bioavailability. Choice D is incorrect as combining an active drug with an inert substance can affect bioavailability, such as altering absorption rates.

Correct Answer: A

Rationale: The correct answer is A: Synergistic. When two drugs have a synergistic interaction, they work together to produce a stronger effect than if used alone. In the case of pain meds, combining two drugs that have a synergistic interaction can lead to enhanced pain relief. This occurs because the drugs act on different pathways to produce a more effective outcome. Choices B, C, and D are incorrect: B: Antagonistic - This would mean the drugs work against each other, reducing the overall effect. C: Potentiative - This term implies that one drug enhances the effect of the other, but synergistic interaction implies a stronger combined effect. D: Additive - While this term suggests the drugs work together, it does not capture the idea of a synergistic interaction where the combined effect is greater than the sum of individual effects.

Correct Answer: B

Rationale: The correct answer is B: Half-life. Half-life is the time taken for the drug concentration in the body to reduce by 50%. This is a fundamental pharmacokinetic parameter used to determine dosing intervals. Steady state (A) refers to when drug input equals drug elimination, Phase II metabolism (C) is a type of drug metabolism, and Reduced bioavailability time (D) does not accurately describe the concept of drug elimination. In summary, half-life is the specific term that quantifies the rate of drug elimination in the body, making it the correct answer in this context.

Correct Answer: D

Rationale: The correct answer is D because enteric-coated tablets are designed to bypass the stomach and dissolve in the intestines for optimal absorption. Taking them with at least 8 ounces of fluid helps ensure the tablet reaches the intestines intact. Choice A is incorrect as it is not necessary to avoid all other oral medicines. Choice B is incorrect as dissolving an enteric-coated tablet can affect its effectiveness. Choice C is incorrect because crushing the tablet can also interfere with its intended delayed release mechanism.

Correct Answer: B

Rationale: The correct answer is B: A rich blood supply to the area of absorption leads to better absorption. A rich blood supply enhances drug absorption by allowing for faster diffusion of the drug into the bloodstream. This is because a greater blood flow increases the concentration gradient, facilitating quicker absorption. Explanation for why the other choices are incorrect: A: The statement that the smaller the surface area for absorption, the more rapidly the drug is absorbed is incorrect. Larger surface area typically leads to faster absorption due to increased contact with absorbing surfaces. C: The statement that the less soluble the drug, the more easily it is absorbed is incorrect. Solubility affects dissolution, not absorption. D: The statement that ionized drugs are easily absorbed across the cell membrane is incorrect. Ionized drugs have lower permeability across cell membranes compared to non-ionized drugs.