Anticholinergic / opioid combinations are used to treat bladder pain and diarrhea. These medications work by combining the pain-relieving effects of opioids with the muscle-relaxing properties of anticholinergics. Some of these medications come in oral forms, while others are available as suppositories. Examples include belladonna / opium and difenoxin / atropine (Motofen). Your prescriber can help you choose the form that best fits your needs.