What is enterohepatic recirculation, and what pharmacokinetic pattern might indicate its presence?

What is enterohepatic recirculation, and what pharmacokinetic pattern might indicate its presence?

• A. Reabsorption of drug or metabolites from bile back into circulation; secondary peaks or prolonged apparent half-life.
• B. First-pass metabolism in the liver leading to reduced systemic exposure.
• C. Drug accumulation in adipose tissue causing long-term storage.
• D. Active transport of drug into the liver increasing clearance.

Answer: (A)

Enterohepatic recirculation is a looping process where a drug or its metabolites are excreted into bile, enter the intestine, and are reabsorbed back into the bloodstream to return to the liver. This recycling often involves drug conjugates in bile that can be deconjugated by gut bacteria, freeing the active drug to be reabsorbed. The pharmacokinetic pattern you’d expect from this process is a secondary rise in plasma concentration after the initial decline (a secondary peak) and a longer apparent terminal half-life due to the repeated re-entry of drug into circulation. Meals can influence the timing because bile flow increases after eating, enhancing reabsorption. This pattern distinguishes enterohepatic recirculation from other processes. It isn’t primarily about first-pass metabolism reducing systemic exposure, storage in adipose tissue, or active transport increasing clearance, all of which describe different pharmacokinetic behaviors.

Enterohepatic recirculation is a looping process where a drug or its metabolites are excreted into bile, enter the intestine, and are reabsorbed back into the bloodstream to return to the liver. This recycling often involves drug conjugates in bile that can be deconjugated by gut bacteria, freeing the active drug to be reabsorbed.

The pharmacokinetic pattern you’d expect from this process is a secondary rise in plasma concentration after the initial decline (a secondary peak) and a longer apparent terminal half-life due to the repeated re-entry of drug into circulation. Meals can influence the timing because bile flow increases after eating, enhancing reabsorption.

This pattern distinguishes enterohepatic recirculation from other processes. It isn’t primarily about first-pass metabolism reducing systemic exposure, storage in adipose tissue, or active transport increasing clearance, all of which describe different pharmacokinetic behaviors.