Hyomax is not one of your typical pain drugs in that its specifically used to treat one type of pain; gastrointestinal pain such as cramping that is associated with irritable bowel syndrome, kidney stones, etc. Instead of working on the pain pathways in the brain or nervous system such as many pain drugs do Hyomax relaxes the muscles in the organs such as the stomach, intestines, etc. and decreases acid production in gut. Its also used to treat Parkinson's disease.
http://fdb.rxlist.com/drugs/drug-150615-HyoMax-SR+Oral.aspx?drugid=150615&drugname=HyoMax-SR+Oral