n.
Heterocyclic compound , a naturally occurring alkaloid found in opium , used in medicine as a cough suppressant and analgesic drug.
It exerts its effects by acting on the central nervous system (brain and spinal cord). Chemically it is methylmorphine, the methyl ether of morphine , an alkaloid of the phenanthrene type; its action is weaker than that of morphine, and it is less likely to lead to drug addiction .