Levigation is the answer to this. There are various reasons why people would need to grind tablets into powder form. Some would need to do this so that other people will not see it as they place it into their food and drinks.
This can be dangerous, especially if the content of the medication is fatal to the other person. For example, there may be some people who cannot drink aspirin because they are allergic. Someone who may want to make them have an allergic reaction may grind aspirin and add it to their food and drinks. This is a process that should be avoided.
This is the process wherein you would be grinding a substance that is usually insoluble into a fine powder. Take note that in order to do this properly, the substance has to be wet. This needs to be mixed in together with water. The substance can flow like water or it may also be like a thin paste.
Remember that only a certain amount of liquid should be used in order to make this process possible. Some would try to do this on their own but they would end up using too much liquid. Always get to know how much you need to use to get the best results.