I'm a big fan of macro photography as well as biomedical engineering, so this video really struck a chord with me. If you are interested in seeing how pills dissolve and break open once they hit your system, check out the incredible video below. Afterward, we will get into the technology and chemistry behind pills.
Let's talk about the purpose of pills and how this affects how they dissolve.
Some pills are meant to be quick release, say for a headache, and others are meant to release the medicine over extended periods of time. Most pill capsules are designed to react in certain ways to the pH of the stomach. Aspirin, for example, has an enteric coating, which is meant to keep it safe in the low pH environment of the stomach until it reaches the intestines. Typically, drugs treated with this coating could not survive the harsh environment of the stomach, so in order for proper treatment they must be dissolved in the intestines.
For some drugs, a quick absorption of the compounds would do more harm than good to the patient.
For these, the coatings of the pills are created to rupture slowly and in acute ways. This allows the medicine to seep out over a long period of time. In terms of medical treatment, just getting the drug in your system is only half the battle, how the drug is administered makes a huge difference. For example, swallowing a suppository would do you no good, and it would also be a little gross. Ew. This principle is why name brand drugs may be better than the generic brand. Advil may have a better release mechanism for administering the compounds than your generic ibuprofen tablets. It isn't just all in your head.
To go into a little more specifics of pill design, tablets are chemically designed to release drugs at certain speeds. Not all tablets are alike. Gel capsules are typically designed to release drugs very quickly. Take for example the common gel capsule of Nyquil/Dayquil. These are meant to hit your system fast and start fighting your cold right away.
Believe it or not, some slow release coatings can be designed to allow a pill to survive in your system for over 12 hours before the drug gets released.
These specific designs in drug capsules are also why medicines expire. If you leave pills on the shelf for too long, not only does the medicine become less effective, but the capsule can degrade causing incorrect drug administration, increasing chances for complications.