Ion Trapping Pharm Intro Tutorial: Aspirin weak acid, charge selective membrane

Uploaded by helphippo on 30.05.2012

Ion Trapping effectively means that strong acids in the stomach push “weak acid drugs”
through a charge selective membrane into the blood without using energy.
How? We'll explain in 4 stages.
A membrane separates two compartments. This is your stomach, this is your blood.
You eat 6 dots that get in your stomach, and eventually you'll have 3 dots on each side.
Second: you have a charge selective membrane. Uncharged dots can still cross the membrane,
but charged dots can NOT cross and get trapped. So if you put 6 acid dots on one side, you'll
still have 6 acid dots there later.
Third: Aspirin can take a charged or uncharged form - depending on the environment.
In the blood, aspirin is charged, so can NOT cross the membrane.
In the stomach, aspirin is scared by the strong digestive acids nearby....
so aspirin takes its uncharged form.
This uncharged aspirin can cross the membrane.
Fourth: Aspirin gets in to the stomach and takes its uncharged form.
This uncharged form crosses the membrane.
Once in the blood, aspirin converts to its charged form.
The charged aspirin is now trapped because the “charge selective membrane”
blocks it from returning to the stomach.
This “ion trapping” happens repeatedly to get aspirin in to the blood, without using
You can also use ion trapping to get an overdose of aspirin into basic urine.
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