Question: why would the shape of molecules help to design drugs?

Lizzard O'Day answered on 13 Jun 2011:

Designing drugs is a lot like putting a puzzle together. Say you’re doing a puzzle of an image of “Big Ben”, you’re trying to fit together the pieces, well the easiest ones would be of the tower and clock, you can see how they fit together, the surrounding sky can be difficult because everything looks the same. Figuring out what molecules looks like help us fit puzzle pieces together easier. It gives us an idea of what may work in one setting or what may not fit at all. Figuring out the shape (or structure) of what molecules look like helps us identify the target and then we can go after it for a drug.