 Morphine is a benzylisoquinoline alkaloid with two additional ring closures.As Jack DeRuiter of the Department of Drug Discovery and Development (formerly, Pharmacal Sciences), Harrison School of Pharmacy, Auburn University stated in his Fall 2000 course notes for that earlier department's "Principles of Drug Action 2" course, "Examination of the morphine molecule reveals the following structural features important to its pharmacological profile...

Morphine and most of its derivatives do not exhibit optical isomerism, although some more distant relatives like the morphinan series (levorphanol, dextorphan and the racemic parent chemical dromoran) do, and as noted above stereoselectivity in vivo is an important issue.Most of the licit morphine produced is used to make codeine by methylation.