The impetus for the treaty was the popularity of new, uncontrolled opiate derivatives that were outside the scope of the Permanent Central Board's restrictions. In particular, manufacturers were switching from morphine to pethidine, methadone, and other designer drugs to evade the international restrictions. The similarity concept was specifically designed to combat these tactics.
In addition, every Party to the Protocol was committed to inform the UN Secretary-General of any drug used or capable of being used for medical or scientific purposes (and not falling within the scope of the 1931 Convention) which that party considered capable of abuse and of producing harmful effects. The Protocol also authorized the Commission on Narcotic Drugs to place such a drug under provisional control. The provisional control measures might be altered in the light of the conclusions and decisions of the World Health Organization (and subsequently in the light of experience).