In a way, drug discovery is like searching for a molecular key (the drug) to open the disease’s lock.

Scientists try to find out the structures of the key and lock as well as how different keys interact with the lock.

To have a good fit and block the drug target’s function, the molecular key must be complementary in its geometric shape and its interactions with a cavity in the biomolecule. The challenge lies in finding a way to test the plethora of available keys against the vast number of accessible locks.

Also a lock may not be found for every disease & one key may fit into multiple locks.