The Collaborative International Dictionary of English v.0.48:

opianine \o"pi*a*nine\, n. (Chem.)
   An alkaloid (C22H23NO7) found in small quantity in opium.
   It is identical with narcotine. It is present in amounts up
   to 11% in Papaver somniferum, and is used clinically as an
   antitussive. --MI11

   Syn: noscapine; narcosine; opian.
        [1913 Webster +PJC]