This learning model is currently available in English.
Explore the system
Transform, then eliminate
Follow Phase I and Phase II reactions, and see how enzyme induction and inhibition change the model.
Sources and model limits
Original schematic. Positions show relationships; structures and concentrations are not to scale.
- Julien's Primer of Drug Action · 15 · 1 · Transform, then eliminate · PDF 15, 16, 17 · 1.8, 1.9
Course notes and existing practice
Learning objective
Predict the direction of a simple parent-drug interaction while identifying the assumptions behind it.
Changing metabolic capacity
Enzyme induction increases relevant enzyme expression or activity; inhibition reduces enzyme activity. In a simple model of an active parent drug cleared by that enzyme, greater metabolic capacity can reduce parent exposure, while inhibition can increase it. The prediction depends on which compound is active and which pathway controls its handling. It cannot be generalized unchanged to prodrugs.
People and environments differ
The lecture highlights genetic variation, age, liver disease and other substances as influences on metabolism. Metabolizer categories are specific to an enzyme or pathway rather than a single permanent ranking of a person as a slow or fast metabolizer of everything. The grapefruit figure illustrates an interaction, not a recommendation to manipulate exposure. Specific alcohol, buspirone and carbidopa examples in the slides require separate editorial checking.
- Enzyme induction
- An increase in relevant enzyme expression or activity.
- Enzyme inhibition
- A reduction in an enzyme's activity.
Professor deck 04, PDF pages 37, 38, 39, 40. 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.