Drugs inside a soft, waxy substance that is put into the back passage (rectum).  The drugs are absorbed into the lining of the rectum and go into the bloodstream. This is a fast way of getting drugs into your system and is helpful if eating or drinking are a problem. Glycerine suppositories do not contain a drug but give lubrication to help you pass a bowel motion if you are constipated or need to empty the rectum before an operation.