many medications are formulated in a special way to slowly release the medication over time. some of these formulations may result in a "shell" being passed through the stool. the shell appears to be a whole tablet. but normally the shell has been rendered empty of the medication. it really depends on what medication you are referring to in order for me to tell you if it is normal and expected. i suggest you ask your pharmacist if the medication you are using could lead to the expulsion of shells in your stool.
what does it mean when a prescription drug does not dissolve but is found whole in the stool?