Methadone is synthetic heroin substitute and is the tried and trusted route for heroin addicts trying to kick the habit.

BBC: Prostitute - anonymous image

Another reason for the drop in cultivation may also be due to the fact that the US market - the world's biggest - is experiencing a rise in popularity of synthetic drugs over cocaine and heroin supplied by Colombia.

BBC: Colombia's coca crops drop

Desmorphine, a synthetic with similar effects of heroin made from house-held chemicals like codeine (available over the counter in Russia), iodine, lighter fluid, gasoline, and industrial cleaning oil, is street-named Krokodil for the way it literally devours its users (like the mean crocodile).

FORBES: Krokodil and the Terrible Cost of the War on Drugs