There are so many to choose from now and some really ingenious delivery systems. For instance, Concerta is a plastic pill surrounded by a hard dose of MPH (methylphenidate). The outer shell of MPH burns off in your stomach providing an immediate dose of the medication. And inside the plastic capsule, there is more MPH in a liquid form. The inner liquid MPH slowly leaks out by osmosis via a tiny hole in the plastic inner shell.
How anyone thought of this and made it actually work is mind boggling.