As a general rule you don’t tend to have flaws, such as spice addiction, in the 2D20 system. Though there is nothing to stop a character declaring that they have one.
Otherwise the GM could apply a Trait to an NPC of ‘Spice Addiction’ which could presumably be used to give benefits or negatives to interactions with them based on how it was being used.
2D20 is a fairly light system most of the time (Infinity aside 
) and Dune is definitely on the lighter end of the spectrum.