All drugs continue to act in the body until they are changed or excreted. The ability of the body to excrete drugs via the renal system would be increased by:

Correct Answer: D

Rationale: Step-by-step rationale for why choice D is correct: 1. Unbinding a nonvolatile drug from plasma proteins increases the drug's free concentration in the blood. 2. Increased free drug concentration enhances the drug's ability to be filtered by the kidneys. 3. Higher filtration of the drug leads to increased excretion through the renal system. 4. Therefore, unbinding a nonvolatile drug from plasma proteins enhances the body's ability to excrete the drug efficiently. Summary of why other choices are incorrect: A: Reduced circulation and perfusion of the kidney would decrease the excretion of drugs. B: Chronic renal disease impairs renal function, reducing drug excretion. C: Competition for a transport site by another drug may affect distribution but not necessarily increase drug excretion.

Correct Answer: D

Rationale: The correct answer is D: Down-regulate the numbers of that specific receptor. Step 1: When an agonist continuously activates a receptor, the body may reduce the number of receptors to maintain homeostasis. Step 2: Down-regulation is a feedback mechanism to decrease receptor sensitivity due to excessive stimulation. Step 3: This helps prevent overstimulation and desensitization of the receptor. Summary: A: Up-regulating the total number of receptors is unlikely as the body typically down-regulates in response to prolonged agonist exposure. B: Blocking the receptor with a partial agonist is not a typical response to repeated agonist exposure. C: Altering the drug's metabolism is not directly related to receptor down-regulation in response to agonist stimulation.

Correct Answer: B

Rationale: The correct answer is B: Toxicity. Crushing a sustained-release capsule can disrupt the controlled release mechanism, leading to the rapid release of a potentially toxic dose. This can overwhelm the body's ability to metabolize the drug safely, causing toxicity. Disintegration (A) would not be the major concern as the beads would still release the drug. Malabsorption (C) is less likely as the drug would still be absorbed, albeit possibly too quickly. Deterioration (D) refers to physical changes in the drug, not toxicity.

Correct Answer: A

Rationale: The correct answer is A: Absorbed rapidly. Sublingual medication is absorbed directly into the bloodstream through the mucous membranes under the tongue, bypassing the digestive system and liver first-pass metabolism. This route allows for faster onset of action and higher bioavailability compared to oral ingestion. Excretion rate (option B) and distribution pattern (option D) are not specific advantages of sublingual administration. While metabolism may be reduced (option C), the primary advantage is the rapid absorption.

Correct Answer: C

Rationale: The correct answer is C: An exaggerated response if the drug is withdrawn. Up-regulation or hypersensitization involves an increase in the number or sensitivity of receptors, leading to an intensified response when the drug is suddenly stopped. This occurs due to the heightened receptor activity and can result in withdrawal symptoms or rebound effects. Choices A and B are incorrect because up-regulation typically results in increased, not decreased, response to the drug. Choice D is incorrect as refractoriness or complete lack of response is more indicative of down-regulation or desensitization.