The list of medications that cannot be broken, crushed or chewed is quite extensive, and the answer is not always straightforward. One important consideration is how quickly the medication is supposed to be released in the body to have its desired effect. In general, if a tablet or capsule is designed to be released slowly throughout the day (i.e., extended-release, sustained-release, controlled-release, long-acting, etc.) it should not be broken, crushed or chewed.
You should also consider whether the medication is coated. The purpose of certain coatings is to keep the medication intact as it travels through the acid in the stomach so it can reach the area where it will be absorbed without being broken down. Another reason for coating tablets might be to protect the stomach from being exposed to medication that is irritating, such as aspirin. Other reasons that a medication should not be broken, crushed or chewed may be to prevent unpleasant taste or irritation to the lining in the mouth.
There may be other reasons your medication should not be broken, crushed or chewed. When in doubt, ask your pharmacist.