Pharmacokinetics & Medication Safety

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Abstractions about absorption, metabolism, clearance, dosage, potency, drug interactions, adverse reactions, polypharmacy, and therapeutic endpoints.

13 abstractions in this family — domain-specific abstractions that sit near one another in structural-signature space (k-means over structural-signature embeddings). Each is shown with its short description.

• Absorption Phase — Carve out the rising limb of a drug's plasma curve as a distinct stage with its own two determinants — how fast the dose crosses into circulation and how much survives to arrive — so before-circulation variability is not confused with what happens after.
• Adverse Drug Event — Harm to a patient caused by the pharmacology of a drug rather than the process of delivering it — bracketing mechanistically unlike injuries under one causal structure so the prescribing question becomes a benefit-to-harm ratio, not a binary safety verdict.
• Adverse Drug Reaction — Classify an unintended, harmful response arising under correct drug use — not through any administration error — by an ABCDEF taxonomy whose pivotal dose-related-versus-idiosyncratic split reads off predictability, remedy, and whether trials could ever have caught it.
• Clearance — Express the body's power to eliminate a substance as the virtual volume of plasma fully cleared per unit time (Cl = elimination rate / concentration), a concentration-independent capacity that sums additively across organs.
• Cumulative Dose — Locate biological harm or benefit in the time-integral of an exposure stream rather than any single event, so a course of individually safe doses can still cross a threshold on the running stock — which reducing the present rate cannot undo.
• First-Pass Metabolism — Explain why an oral drug's dose depends on its route by tracking one obligate pre-systemic compartment — the splanchnic-hepatic transit — and the extraction ratio E that sets oral bioavailability as F = 1 − E.
• Idiosyncratic Reaction — Classify a rare drug harm as a distinct causal category — dose-independent, qualitatively different in kind, and confined to a small biologically-defined susceptible tail — so it is understood not as too-much-drug but as uniform exposure meeting a heterogeneous responder population.
• Pharmacokinetic Interaction — Locate a drug-interaction failure at the exposure layer — one substance altering another's absorption, distribution, metabolism, or excretion so its concentration-time profile shifts at an unchanged dose — rather than as opposition at a shared receptor.
• Pharmacological Interaction — Treat two co-present pharmacological agents as a coupled system when one changes the other's exposure or action, or their joint effect departs from the effect expected if each operated independently; then localize the coupling to the pharmacokinetic exposure layer or the pharmacodynamic effect layer.
• Polypharmacy — Shift the unit of clinical attention from the single prescription to the whole regimen, sorting the combined risk of concurrent drugs into three channels — pharmacokinetic collisions, pharmacodynamic summation, and the prescribing cascade — under one appropriate-versus-problematic binary.
• Potency — Quantify how much drug a given effect costs by reading one coordinate off the dose-response curve: the dose that produces half the maximal response (the ED50), so a lower value means less drug suffices.
• Surrogate Endpoint Problem — The failure that arises when a trial's biomarker surrogate diverges from the clinical endpoint it stands in for — because the intervention acts through off-pathway mechanisms the surrogate cannot see — so individual-level correlation does not license an intervention-level claim.
• Therapeutic Duplication — The medication-safety failure where uncoordinated prescribers each place a defensible order that lands on the same pharmacologic target, so additive exposure overruns the therapeutic window — a harm that lives in the set of orders, not in any single one.