Nokea
Which of the following can effect drug absorption into the body?
- A. Dosage Form
- B. Site Surface area
- C. Blood flow to site of absorption
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D, "All of the above." Dosage form affects drug absorption by influencing the rate and extent of dissolution. Site surface area affects drug absorption as a larger surface area allows for more contact with the drug. Blood flow to the site of absorption impacts drug absorption by affecting the rate of delivery of the drug to systemic circulation. Therefore, all three factors (dosage form, site surface area, and blood flow) play crucial roles in drug absorption into the body.
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Which of the following terms best defines a beta-blocker that binds reversibly to beta receptors?
- A. Partial agonist
- B. Functional antagonist
- C. Inverse agonist
- D. Noncompetitive antagonist
Correct Answer: D
Rationale: A noncompetitive antagonist best defines a beta-blocker that binds reversibly to beta receptors because it binds to a site on the receptor that is not the same as the agonist binding site, thereby preventing the receptor from being activated by the agonist. This type of antagonist does not compete with the agonist for binding to the receptor, making it an effective blocker of receptor activation. In this case, the drug had no intrinsic activity and only bound reversibly to beta receptors, indicating its role as a noncompetitive antagonist.
Drugs that are receptor agonists may demonstrate what property?
- A. Irreversible binding to the drug receptor site
- B. Up-regulation with chronic use
- C. Desensitization or down-regulation with continuous use
- D. Inverse relationship between drug concentration and drug action
Correct Answer: C
Rationale: The correct answer is C: Desensitization or down-regulation with continuous use. Receptor agonists continuously activate receptors, leading to desensitization or down-regulation where the receptors become less responsive or decrease in number. This occurs due to the body's attempt to maintain homeostasis in response to constant stimulation. Choices A and D are incorrect because receptor agonists do not typically bind irreversibly or exhibit an inverse relationship between drug concentration and action. Choice B is incorrect as up-regulation is usually observed in response to receptor antagonists, not agonists.
What was most likely the immediate consequence of the activation of beta receptors in the 9-year-old boy suffering from mild asthma?
- A. Opening of ligand-gated K+ channels
- B. Increased synthesis of cAMP
- C. Decreased synthesis of cAMP
- D. Conformational change of a G protein
Correct Answer: B
Rationale: The immediate consequence of beta receptor activation is increased synthesis of cAMP, which is a key signaling molecule in the downstream effects of beta receptor activation.
Up-regulation or hypersensitization may lead to:
- A. Increased response to a drug
- B. Decreased response to a drug
- C. An exaggerated response if the drug is withdrawn
- D. Refractoriness or complete lack of response
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.
The point in time on the drug concentration curve that indicates the first sign of a therapeutic effect is the:
- A. Minimum adverse effect level
- B. Peak of action
- C. Onset of action
- D. Therapeutic range
Correct Answer: C
Rationale: The correct answer is C: Onset of action. This is the point in time when the drug concentration reaches a level where the therapeutic effect begins to be observed. The onset of action signifies the start of the drug's intended effect on the body. The minimum adverse effect level (Choice A) refers to the lowest concentration at which side effects may occur, not the therapeutic effect. The peak of action (Choice B) is the point when the drug's effect is at its maximum, not necessarily the first sign of therapeutic effect. The therapeutic range (Choice D) is the range of drug concentrations that produce the desired therapeutic effect without causing significant side effects, but it does not specifically indicate the onset of therapeutic action.