Some key facts before you watch the video on aspirin absorption:
- Aspirin is a weak acid (pKa 3.4).
- Acidic drugs in an acidic environment (like gastric lumen) are most likely to be in their neutral form ( non-ionized )
- Non-ionized drugs are more lipid soluble. Hence, they can be readily absorbed
- Since aspirin is a weak acid and gastric pH is an acidic environment, it can be readily absorbed.
- Bloodstream has a pH of around 7.4, therefore aspirin tends to be ionized. This prevents the drug from diffusing back to the stomach.
Now, watch again the video paying attention to the following details.