I have had some further thoughts after my previous question regarding the buccal delivery of medication. The active compound in aspirin (acetylsalicylic acid or systematically 2-Acetoxybenzoic acid) is salicylic acid (2-hydroxybenzoic acid).
I understand that the hydrolysis reaction occurs as follows within the stomach - therefore in the body it is an acid hydrolysis:
N.B. The H2O is not shown in the diagram.
However having done this experimentally I know that in the lab to ensure a decent yield of salicylic acid I had to reflux the solution for several hours. Yet the onset of action of aspirin tablets is much faster than this. To me this suggests some enzymatic activity, but I have no idea which enzyme this is likely to be.
To follow on directly from my previous question, if the aspirin is absorbed directly into the bloodstream bypassing the stomach then what causes the hydrolysis in the blood stream and is it the same factor that increases the rate of hydrolysis in the stomach if the medication were to be taken orally?