First Pass Metabolism

[brainiacthemaniac]

What exactly is first pass metabolism? I have some idea what this means with regard to the alimentary canal and duodenal absorption, but the first pass thing confuses me. Thanks for the help.

[fastandbulbous]

Blood from the intestines (containing food, drugs etc) goes to the liver first before being returned to the heart/lung system. It's so the liver can metabolize out nasty compounds, but it means some drugs get heavily metabolized before they have a chance to get to the brain. Routes that don't involve the small intestine also avoid going straight to the liver

[brainiacthemaniac]

FB, so if I read that correctly it is the metabolism that causes a significant reduction in the potency of some medications as a result of the absorption from the stomach/duodeum into the bloodstream?

This would be the reason that parachuting and "booty" bumping (edit) tend to make lipophilic drugs more psychoactive?

Thanks FB..

[DexterMeth]

^booty bumping..KandyK lives on.

[BilZ0r]

This would be the reason that parachuting and "booty" bumping (sorry for the gay ass term) tend to make lipophilic drugs more psychoactive?

Most people think parachuting is swollowing a crushed up pill in tissue paper or something... and it's still subjected to first pass metabolism; anything that gets swollowed is.

When you plug (booty bump) stuff, you avoid first pass to a degree, though probably not as much as a lot of people think, as blood from the colon still majoratively passes to the liver.

For more information on metabolism: Pharmacokinetcs.

[brainiacthemaniac]

Thanks guys..I couldnt remember the plugging thing..