A 13-year-old boy with moderate asthma presents to the clinic for follow-up. His symptoms appear to be better controlled since adding salmeterol to his regimen. He has had to use his rescue inhaler once over the past 2 weeks during exertion. His breathing at night has improved as well. How does salmeterol exhibit its beneficial effects for asthma?

Correct Answer: D

Rationale: Salmeterol improves asthma as a long-acting β2-agonist , relaxing bronchial smooth muscle for 12 hours. β1 agonism (A, C) affects the heart. β1 antagonism or β2 antagonism (E) worsen asthma. Salmeterol's specificity enhances control.

Correct Answer: B

Rationale: Diazepam, a benzodiazepine, has active metabolites (e.g., desmethyldiazepam) with longer half-lives, contributing to its effects, so that's false. Activated charcoal is effective in overdose by adsorbing diazepam, reducing absorption, a true statement and standard intervention. It undergoes minimal, not extensive, enterohepatic recirculation, making that false. It's a GABA agonist, enhancing chloride influx via benzodiazepine receptors, not an antagonist, so that's incorrect. It also inhibits spinal reflexes, aiding muscle relaxation. The overdose utility of charcoal highlights its role in emergency management, binding unabsorbed drug in the gut, a key pharmacokinetic intervention distinct from flumazenil reversal.

Correct Answer: C

Rationale: Protamine sulfate is the antidote for heparin overdose. Heparin is an anticoagulant medication that works by inhibiting the action of thrombin and factor Xa. Protamine works by binding to heparin and neutralizing its anticoagulant effects. This helps to reverse the effects of heparin and control excessive bleeding in cases of overdose. It is important to administer protamine sulfate promptly to counteract the effects of heparin and prevent further bleeding complications. Options A, B, and D are not the correct antidotes for heparin overdose.

Correct Answer: D

Rationale: A drug that has both affinity and intrinsic activity is known as a partial agonist. Affinity refers to the drug's ability to bind to a receptor, while intrinsic activity is the drug's ability to activate the receptor and produce a response. A partial agonist binds to the receptor with affinity but only activates the receptor to a partial extent compared to a full agonist. This results in a less potent response compared to a full agonist but also blocks the full agonist's effects, making it act as an antagonist in the presence of a full agonist. In summary, a drug that has both affinity and intrinsic activity is classified as a partial agonist because it binds to the receptor and activates it but to a lesser extent than a full agonist.

Correct Answer: D

Rationale: Magnesium sulfate prevents seizures in preeclampsia via CNS depression. Absence of seizures indicates therapeutic effect, the primary goal. Decreased BP isn't magnesium's role'antihypertensives manage that. Increased urine output isn't specific. Reduced reflexes signal toxicity, not efficacy. Seizure prevention aligns with magnesium's mechanism, critical in preeclampsia where eclamptic risk is high, making D the key finding of successful therapy.