New Psychoactive Substances (NPS)
"The creation of new substances to exploit loopholes in drug control legislation has been a problem since the international drug control system was first established. The proliferation of such substances in recent decades was influenced by the work done by Ann and Alexander Shulgin on phenethylamines8 and tryptamines9 in the 1960s and the 1970s. The Shulgins reported over 230 psychoactive compounds that they had synthesized and evaluated for their psychedelic and entactogenic potential. More recently, a number of piperazines, synthetic cathinones and synthetic cannabinoids emerged, which were marketed as 'legal' alternatives to controlled substances."
UNODC, World Drug Report 2013 (United Nations publication, Sales No. E.13.XI.6), p. 60.