Modafinil price table: updated, +brands, +armodafinil table

So many conflicting studies on modafinil! There is most definitely a difference in half life. Anecdotes confirm this finding. The spatial location of the functional groups on the molecule are the cause for this. S-modafinil can be metabolized by CYP3A4 into modafinil sulfone. This is what gives users of racemic the sulfur smell in their urine. R-modafinil cannot be metabolized by CYP3A4, due to the carbonyl groups blocking it. R-modafinil goes through amide hydrolysis, creating modafinil acid. This process takes longer than CYP3A4 metabolism. This is why the half lives are different.

Here is an interesting paper about the crystal and molecular structure of both enantiomers, and their effects. They are postulating that both the S and R enantiomers have the same effects, and their CNS activity is due to the spatial orientation between the diphenyl and amide groups, which are the same in both. That would mean that the subjective difference in effects is solely due to competitive binding, competitive absorption, and metabolism. I have read other papers showing different binding affinities as well, so I am not sold one way or the other yet.