Discussion Guide — Chapter 29

Six prompts. Each is followed by what to listen for — the responses that indicate genuine understanding, and the ones that indicate a plausible-sounding miss.

Prompt 1 — "Name three peptide drugs." Why did that question work?

Ask at the start; revisit at the end.

Listen for: recognition that the failure was not ignorance but categorization — students knew these drugs, they had them filed elsewhere. The strongest responses connect this to how clinicians organize by function (§29.5) and how the wellness market organizes by molecular class, and notice that the two failures compound: the professionals who use peptides do not see the category, and the market that names the category does not use the drugs.

Watch for: students treating it as a trivia gap ("I just hadn't heard of teriparatide"). Push back: had they heard of vancomycin? Cyclosporine? Oxytocin? The answer is almost always yes.

Prompt 2 — Continuous PTH destroys bone; intermittent PTH builds it. What does that tell us about how to reason about hormone therapy in general?

Listen for: the distinction between a property of a molecule and a property of an exposure. Strong responses note that this reframes what a drug even is — the schedule is not an implementation detail, it is part of the intervention. Excellent responses connect it forward: the reasoning "this hormone does X, so more of it does more X" is ubiquitous in peptide marketing and would have predicted exactly the wrong answer here.

Watch for: "less is more" as the takeaway. It is not a dose story. Also watch for students supplying a confident mechanism — the mechanism is not settled and the text says so; a student who claims certainty about the osteoblast/osteoclast coupling has over-read.

Prompt 3 — Calcitonin's role shrank with no scandal, no suppression, and no villain. Is that reassuring or is it just a slower failure?

This is the best prompt in the set. Let it run.

Listen for: engagement with the fact that a drug can lose its place by being outperformed rather than disproven, and whether students find that acceptable. Strong responses identify the three independent strands and argue about which was decisive. The best responses arrive at the closing move on their own: the thing that matters is not that calcitonin lost, but that a mechanism existed by which it could lose — and that the unregulated market has no such mechanism.

Watch for: cynical deflection ("the patent expired, that's all"). Take it seriously and press: commercial factors were real, but can they explain the direction of the revision? The regulatory reviews and the weak fracture evidence were independent of patent status.

Also watch for students who cannot tolerate a story without a villain and start manufacturing one. Name that impulse; it is the same impulse that makes conspiracy narratives about medicine attractive.

Prompt 4 — Cyclosporine is a peptide you can swallow, and it made transplantation practical. What does that exception license you to believe about oral peptide products?

Listen for: precision about scope. The exception establishes that oral peptide bioavailability is an engineering problem with known solutions — cyclization, D-residues, N-methylation — not a physical impossibility. It does not transfer credibility to any product that has not done that engineering.

Watch for: two opposite errors. Some students over-generalize ("so oral peptides can work, the skeptics were wrong"). Others dismiss ("it's a weird fungal molecule, it doesn't count"). Both miss. The right posture is Chapter 1 §1.6's: the burden is on the seller to explain what they solved, and cyclosporine tells you exactly what a real answer looks like.

Prompt 5 — State the strongest objection to the box-six argument, then decide whether it survives.

Require the objection before any response to it. If a student cannot state it, they do not have the argument.

Listen for: a genuine steelman — approval frameworks are built around disease, "optimization" is not a clinical endpoint, so the emptiness may be definitional rather than biological. Then the three responses: unclaimed commercial incentive, thin peptide presence in adjacent approvable categories (prevention, risk reduction), and the pattern independently recurring in Chapter 27's oncology survey and Chapter 37's master table.

Watch for: students who skip the concession. The text concedes that the objection is partly right, and that concession is what makes the responses credible. A student who cannot concede is arguing, not reasoning.

Best responses will identify the weakest of the three responses and say what would strengthen it.

Prompt 6 — Take a peptide claim you have personally encountered. Which of the six boxes does it fall in, and what does that tell you?

Close with this. It converts the chapter into a tool.

Listen for: the discipline of stating the claim in the claimant's own words before classifying it, and of stating only what the prior licenses. Strong responses articulate what would move the claim into a different box — usually an identified deficiency, an identified excess, or a localized pathology — and recognize that a claim which cannot specify those may not be testable as stated.

Watch for: the overshoot. "It's box six, so it's nonsense" is exactly what the chapter does not say, and a student who lands there has traded one unjustified confidence for another. The prior tells you where to spend your skepticism. It does not spend it for you.

Optional extension: ask what would have to be true for box six to fill. This tends to produce the best thinking in the session, because it requires students to imagine a trial design for a claim that has never been operationalized — and to notice how hard that is.