Pharmacolgists look at how drugs interact with a living organism.
One example on top of my head, is the use of acid/base chemistry. Take asprin for example. It is a weak acid, and in acidic aqueous conditions, sparingly soluable only.
- In the acidic conditions of stomach, asprin does not dissolve in water, and hence soluability is rather limited. In the mild basic condition in the small intestine, it becomes deprotonated and charged. This increases its water soluability, and (also due to the large surface of small intestine) is absorbed much more quickly in small intestine.
- I haven't taken asprin tablets before, but I recall the existence of tablets that dissolve in water, before you actually drink it. This is manufactured by adding carbonate (evident in the fizzing of the tablets), which serves as a base, that cause the asprin to be water soluable.