"ya ba" tablets were formerly sold at gas stations and were commonly used by long-haul drivers to stay awake. after many horrific long-distance bus accidents, they were outlawed by the thai government in 1970. the deposed prime minister thaksin shinawatra's campaign from 2003 to eliminate drug-trafficking further helped to curtail widespread use. in particular, use of the drug by bus drivers and truckers is not as widespread as it was in the 1980s.