Hepatic First pass & Enterohepatic Recycling....

[MrsRNn2009]

I really need help understanding in plain terms these 2. Hepatic first pass I kind of understand as being something taken PO and passing the stomach eventually making it to the liver where it's broken down by enzymes and eventually reaches the site of action but the entero hepatic recycling is confusing, is this a good thing or bad?:uhoh21:

[Daytonite, BSN, RN]

One process results in a reduced amount of drug that the body actually ends up utilizing; the other results in an increase in the amount of drug that the body ends up utilizing. Here's how:

First pass metabolism is what occurs when a drug is absorbed from the GI tract. When a drug is taken orally it is absorbed into the portal circulation (the blood vessels of the liver). Many of these drugs are very efficiently metabolized (altered for elimination) as they pass through the portal circulation during this first time. It reduces the amount of active drug that gets into the general circulation. This is first-pass metabolism.

Enterohepatic cycling is where:

1. Unmetabolized drugs as well as drug metabolites go through the liver and biliary tract for excretion and proceed to make their way out of the body through the intestinal tract. In other words, this is the body's way of putting them in the trash and getting rid of them.
   
2. Here's the catch. . .on the way out through the intestines (the entero part of the word enterohepatic) some of the discarded active drug gets reabsorbed back into the blood stream where it is again available to the body for use. In other words, it's being recycled.
   
3. RESULT: The half life and duration of action of a drug is increased.