Why has one of my medications been reappearing in my stool?

I am on several medications for my heart. I also have a mild case of IBS (Irritable Bowel Syndrome). When I went to have my bowel movement this morning, it looked as though one of my medications reappeared in my stools. This particular medication is in the form of a capsule, and the capsule is white and blue in color. What is going on? Does this mean that my body is not absorbing this medication like it is supposed to? This medication is essential for my heart. What do I do?