Apparently, it is a turn-based strategy, with MMORPG influences.
According to Wikipedia:
Drugwars is a turn-based strategy computer game in which the player assumes the role of a drug dealer. The object of the game is to deal the most drugs to pay off the "loan shark" (who charges interest) by the end of the game and make a profit.
And the Zynga variation:
Zynga's rendition of Dope Wars took the basic layout of the original game and turned it into an MMORPG style game with user interaction.