Fentanyl
"I have MS and one of my symptoms is severe pain with muscle spasms.  It gets so bad as to completely debilitate me where I am unable to stand, sit for long periods of time and walk up or down stairs.  This medication is life saving for me.  It has allowed me to return my functioning so that I am mobile again.  I can walk up stairs, work out for short periods of time and live a fairly functional life were I can go to the store, walk around and attend family functions."