Is there is system for naming drugs? I know like -mycins and -illins are antibiotics but is there any real nomenclature for drugs?

Most appear to have just been chosen out of a hat. Why can't drugs just be named after the receptor they act on?
eg Atropine would be renamed "muscarinic receptor inhibitin" or something like that.

Anatomy is easy to remember long term because arteries, nerves, muscles etc are named after their location, function, or supply, but pharmacology appears to be just plain moronic. I can remember them for the test but after a few months memory is gone. Its difficult to form long term memory with a name that has absolutely no link to its action.