If a drug is a significant substrate for P-glycoprotein, what is the expected effect on its systemic exposure?

Study for the Pharmaceutics Xenobiotics Across Bio Membrane Test. Prepare with flashcards and multiple-choice questions, each providing hints and explanations. Get ready for your pharmacy exam!

Multiple Choice

If a drug is a significant substrate for P-glycoprotein, what is the expected effect on its systemic exposure?

Explanation:
P-glycoprotein acts as an intestinal efflux transporter, pumping drugs back into the gut lumen as they are absorbed. When a drug is a significant substrate, a large portion is effluxed before it can reach the bloodstream, reducing the amount that enters systemic circulation. This lowers overall systemic exposure, typically seen as a reduced AUC and often a lower peak concentration. Practically, this is why P-gp substrates can have limited oral bioavailability, and why inhibitors of P-gp can increase exposure.

P-glycoprotein acts as an intestinal efflux transporter, pumping drugs back into the gut lumen as they are absorbed. When a drug is a significant substrate, a large portion is effluxed before it can reach the bloodstream, reducing the amount that enters systemic circulation. This lowers overall systemic exposure, typically seen as a reduced AUC and often a lower peak concentration. Practically, this is why P-gp substrates can have limited oral bioavailability, and why inhibitors of P-gp can increase exposure.

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