Narcotics: the latest chapter in a long story. A review

Extraordinary significant discoveries have been made in the pharmacology of opioid drugs in the last fifteen years. One has to go back to the beginning of the eighteenth century to find a comparably significant period. The advances in our understandings and uses of opioids have taken place in four different areas: postulating the existence of several types of receptors and the discovery of receptors sites, the isolation of endogenous opioids, the development of new opioid substances, and the use of new routes and modes of administration of narcotics.