Discussion Guide — Chapter 2

1. "A peptide doesn't do anything — it says something. Is that a real distinction or a rhetorical one?"

Listen for: students working out that the effect depends on the listener. Push with: "if the message is identical, why does the same hormone do different things in different tissues?" The answer — different receptors, different downstream machinery — is the chapter in one sentence. Watch for students who accept the framing but can't apply it; ask them to predict what happens when a cell has the receptor but not the machinery.

2. "Selectivity is a statement about concentration, not a property of a molecule. What follows from that?"

Listen for: the jump to unstudied doses. If a compound is "selective at therapeutic concentrations," what is it at three times that? Nobody knows, because nobody studied it. This is the cleanest link between Chapter 2's pharmacology and Part III's actual subject matter, and it arrives without any moralizing about self-experimentation, which makes it land better.

3. "Beta-blockers were considered contraindicated in heart failure on mechanistic grounds. The mechanism was correct and the prediction was wrong. How?"

The best question in the chapter. Listen for: students reconstructing the mechanistic argument seriously — blocking a receptor that supports contraction in a failing heart looks obviously harmful, and the reasoning is not stupid. Then let them sit with the fact that trials showed survival benefit. Do not resolve it too fast. The point is not that mechanism was misunderstood; it is that a correct mechanism was embedded in a system complicated enough that the net effect ran the other way.

4. "Oliceridine is approved, works as an analgesic, and the theory it was designed from may be wrong. Is that a success?"

Listen for: the separation of "the drug works" from "the theory was right." Some students will find this deeply unsatisfying — good. Ask what would have happened if the theory had been right and the drug had failed. Both decouplings are real and both are common.

5. "Should a drug's approval increase your confidence in the science behind it?"

A genuinely open question and a useful one. Listen for: the distinction between approval certifying that a drug met its endpoints and approval certifying why. Regulators evaluate evidence of effect, not correctness of theory. Students who get this will read Chapter 38 much better.

6. "Someone tells you 'I keep having to take more for the same effect.' What is your first question?"

Listen for: whether they reach for §2.8 — is this a system being overridden or a deficiency being replaced? — before reaching for a judgment about the person. This question is a rehearsal for Part III and for Chapter 39, and how students answer it predicts how well they will handle those chapters.