Explore the system
Filter, reabsorb, or excrete
Trace the nephron beside its blood supply. Compare a lipid-soluble parent drug with a more water-soluble metabolite.
Sources and model limits
Original schematic. Positions show relationships; structures and concentrations are not to scale.
- Julien's Primer of Drug Action · 15 · 1 · Role of the kidneys and liver in drug elimination · PDF 17 · 1.9
Course notes and existing practice
Learning objective
Distinguish chemical transformation from removal and explain the role of reabsorption.
Leaving the body
The lecture focuses on renal excretion into urine and biliary delivery into feces. It also discusses other routes of loss, including expired air, sweat and milk. Their importance depends on the substance. Listing a route is not a method for accelerating drug clearance.
Filtration is not final excretion
The nephron diagram distinguishes filtration into a tubule from movement along the tubule and collection of urine. Some filtered material can return to blood. The liver-kidney diagram illustrates why lipid-soluble drug can be reabsorbed, while conversion to more water-soluble products can facilitate excretion. Metabolism changes a molecule; excretion removes it. A drug may also be excreted unchanged.
- Excretion
- Removal of drug or metabolites from the body.
- Renal reabsorption
- Movement of material from renal tubular fluid back toward the circulation.
Professor deck 04, PDF pages 28, 29, 30, 31, 32, 33. Course material is paraphrased. Qualifications and excluded clinical generalizations are documented in the Pharmacokinetics editorial record. Source review does not establish clinical validation.
Examples and practice explanations are original study aids, not professor quotations, exam requirements or medication instructions.